sailboat hull core repair

Privacy Guaranteed - your email is never shared with anyone, opt out any time.

GET STARTED

FREE PRINT & DIGITAL EDITIONS

Boat Building & Repair

• Boat Repair
• Fiberglass Boat Repair
• Fixing Broken Stuff

Replacing the Wet Core in Another Spade’s Rudder

By: Don Gutzmer

GBI Technical Advisor

Spring 2024

By Don Gutzmer – GBI Technical Advisor

What happens when the core of a water-damaged rudder can’t be saved? Completely replacing the core of a rudder may need to happen for a variety of reasons. There may be an inability to dry the core and still maintain the structural integrity, or the repair may need to be completed in less time than just letting it dry. The rudder from Another Spade , a C&C 32 sailboat, had a wet foam core that is beyond saving. Here are the steps I used to restore this rudder.

Investigating the Damage

As with any repair, determining the extent of the damage is paramount. One must embody a marine surveyor’s mindset to determine the underlying issue, then devise an effective repair that will also prevent the problem from returning. The first step I took was to “sound” the rudder with a hammer to determine the extent of the wet areas. Sounding is the tapping of a hammer over a cored laminate, listening for the quality of the sound it produces. With the rudder in question, a dull sound was produced when tapping on both sides. With this information, I determined that the entire foam core had gotten wet or was deteriorated to some extent. Next, I drilled several holes into the rudder to determine the integrity of the foam. In some of the holes, the foam came apart easily, even dripping wet. Due to this condition, the foam in the rudder was no longer structurally supportive and past the stage of being saved by simply drying over time. Upon further inspection, I discovered a crack around the top shaft that was likely the culprit of the moisture intrusion.

Removing the Laminate

In order to remove the damaged and waterlogged foam core, I needed to cut away some of the laminate to gain access. To maintain the original shape of the rudder, only portions of the laminate were cut away. This left the general shape intact while also granting access to the inner portion of the rudder. The other advantage to leaving some laminate in place was to have enough surface area to grind a 12:1 bevel angle for adhering the new fiberglass. As seen in the pictures, three sections of laminate on each side of the rudder were removed.

I marked off the area with masking tape and used a vibrating multi-tool to remove the laminate, exposing the foam. A sharp wood chisel and hammer worked well to remove the foam. A small section of laminate was cut away on the leading edge of the rudder to remove additional foam. Once a majority was removed, I placed the rudder in a large oven at 120°F for 24 hours to ensure any remaining foam, and the empty cavity, was thoroughly dry. Alternatively, I could have dried the rudder with heat lamps, but since I have access to an industrial oven with temperature control, I opted to use that.

Determining Replacement Foam

During the demo process, I had set aside an intact section of foam and dried it in the oven with the rudder. I then trimmed this into a 1-inch cube, weighed it, and calculated the density. The density of the foam in the rudder was 6 lbs./ft 3 . I decided to use an 8 lbs./ft 3 polyurethane expanding foam as a replacement, which was more than adequate.

Applying Foam

On the inside of the rudder, there is a metal plate welded to the stainless shaft that runs the length of the rudder. There was rust on the metal plate, so I chose to apply a rust converter called Corroseal® before pouring the foam.

After sanding the metal plate with 36-grit paper, I was ready to test the new expanding foam. I mixed a small test batch and brushed it on the plate to test the strength of the bond. After it cured, I tried to scrape the foam off with a wood chisel. The foam failed, but part of the foam adhered to the plate stayed attached, which indicates good adhesion.

Now that the concept was proven, it was time to actually fill the rudder. Taking advantage of gravity, I flipped the rudder upside down to fill the top portion with foam. The foam cured with a smooth, sealed surface. I used a vibrating multi-tool to remove the sealed surface exposing the textured foam underneath. The smooth surface of the foam could jeopardize good adhesion between layers and eventually separate causing issues later on.

The next area I filled with foam was the leading edge. I stood the rudder up on the leading edge and taped the opening to help contain the foam in the cavity. Once cured, I again removed the smooth surface.

The steel plate in the middle of the rudder worked well as a partition for filling the remainder of the rudder. This way I could fill just one half at a time. All the plate needed was a little tape to cover the hole. I filled half of the rudder with the expanding foam until it rose above the surface of the rudder. Then I let it cure, flipped it over and filled the other half.

Shaping the Foam

The foam that expanded above the surface of the rudder needed to be removed. I used a Japanese pull saw to cut the foam flush with the surface. The sharp saw cut the foam easily and a 6″ pneumatic orbital sander helped to smooth the areas quickly. There were some areas that the foam did not fill and left some pinholes. I mixed a batch of epoxy, thickened with WEST SYSTEM® 410 Microlight® , to fill the imperfections and any low spots. The resulting surface was fair with the original laminate.

Recessing and Beveling

I needed to recess the foam in the openings I had cut into the rudder to accommodate the new skins. The original fiberglass laminate measured 1/8″ thick. I used a router set to that depth to remove the extra foam. The foam needed to be a consistent depth across the entirety of the opening because the fiberglass would follow the contour of the surface below. Any small bits left were removed with a grinder.

The next step was to grind a 12:1 bevel around the perimeter of each opening. At laminate thickness of 1/8″, this meant the bevel would need to be 1 ½” wide. I decided to increase the bevel to 2″ wide to provide ample bonding surface area. I used a 36-grit flap disc to grind the laminate close to the desired bevel angle. I finished refining the bevel using an orbital sander with 60-grit and a little hand sanding.

Laminate Schedule

You may ask, “why didn’t you reuse the old fiberglass laminate instead of installing new fiberglass?” The areas being removed were fairly small, so it was easier for me to layup new fiberglass fabric. This avoids some of the additional grinding that would be required to bevel the old fiberglass panel. I would also still have to layup new fiberglass to bridge over the cut line to make the skin one piece of fiberglass again. If the repair was large, it may have been a smart choice to save the existing fiberglass laminate that was cut off and reuse it on the repair.

As previously determined, the old fiberglass laminate measured 1/8″ thick, and I would be creating a new fiberglass skin to the same dimension. I referenced the WEST SYSTEM User Manual & Product Guide . In the Reinforcing Materials section, the layup thickness chart helped me determine I would need approximately two layers of 10 oz. Glass Fabric (745) and three layers of 17 oz. Biaxial Fabric (737). This was a good starting point.

I laminated a small sample with one layer of 10 oz. fiberglass fabric, three layers of 17 oz. fiberglass fabric, and one additional layer of 10 oz. fiberglass fabric on top to know exactly what thickness I would achieve. There’s a level of variability in the hand layup process so not everyone achieves the exact same results. After measuring my test sample, I realized it was slightly too thick. I opted to swap one layer of 10 oz. fiberglass fabric for a layer of 6 oz. Glass Fabric (742) to achieve the desired 1/8″ thickness.

Fiberglass Application

I created templates to mark out the fiberglass layers for each opening. I chose to use thin paper so I could see the outline of the largest layer through the paper. For each subsequent layer, I marked my template a ¼” shorter along the perimeter. This gave me what’s called a ply drop, creating a gradual transition onto the existing fiberglass laminate. As I cut each fiberglass layer using my templates, I labeled them with an indelible marker. For the first opening, I labeled the pieces 1-1 through 1-5, the second opening was 2-1 through 2-5, and so forth until I had pieces cut for all of my openings.

To have enough working time to layup one whole side of the rudder, I chose WEST SYSTEM® 105 Epoxy Resin® and 206 Slow Hardener® . I applied each layer of fiberglass wet on wet, starting with the largest layer and working to the smallest.

After I had all the layers applied, I waited for the epoxy to set up a little and become tacky. At this stage, I spread a layer of fairing compound (epoxy thickened with 407 Low-Density Filler ) over the entire surface without having to do any additional surface preparation. Having the thickened epoxy on the surface helps fill the weave of the fabric and acts as a starting point in filling any potential low spots. I applied a layer of release fabric over the thickened epoxy and used a plastic spreader at a low angle to smooth the surface. Once cured, I could repeat the same process on the opposite side of the rudder.

Having a smooth surface and a fair surface are two different things—like comparing an apple to an orange. Fairness refers to the shape of the surface, while smoothness refers to the texture of the surface. As a point of reference, a wood batten can be used to judge a fair surface, while the friction you feel running your hand across the surface can help you determine if a surface is smooth.

After removing the release fabric, I had a textured, unfair surface. Not to worry. The next step was to make the rudder surface fair again. I needed to use a long sanding block (longboard) to remove any high spots. The low spots on the rudder are left unsanded due to the longboard bridging across from high spot to high spot. Because of the addition of the filler coat at the end of my fiberglassing process, I did not have to go back and refill any low spots with additional fairing compound.

Repairing the Cracking

Up until this point, I had largely ignored the crack in the fiberglass around the rudder shaft. Having filled the rudder with foam, and the fiberglass skin now repaired, I felt the rudder was stable enough to begin work on the crack. I used a rotary tool to open up the crack. I made sure to open the entire length of the crack so it did not continue to grow after I finished the repair. By opening the crack, it increases the surface area for better bonding.

I chose to use G/flex® 650 Toughened Epoxy because of its superior ability to bond dissimilar materials—the fiberglass, the foam and the stainless-steel shaft. I mixed up a small batch and filled in the opening I had made with the rotary tool. Once it had cured, I sanded it fair to the surrounding area.

Tinted Epoxy Coating

The rudder needed a final coat of epoxy after fairing to seal the surface and fill any pinholes that may have been exposed in the process. I mixed a batch of 105/206 tinted with 503 Gray Pigment. I leveled the rudder and poured a thin layer of the tinted epoxy over the entire surface. This created a uniform coating. I passed a propane torch flame over the wet epoxy to remove any air bubbles within the coating.

After the epoxy cured, I grabbed my trusty longboard to do a final sanding pass. Then I rolled and tipped a couple last coats of tinted epoxy.

To prepare the surface for paint, I used an orbital sander to dull the epoxy’s surface, per the paint manufacturer’s specifications. For this step, I used an orbital sander because I was simply creating the desired texture on the surface, not sanding for fairness.

Professional Repair Method

The process taken to repair this rudder is commonly practiced in boatyards. Trying to dry the foam over time can be sufficient, but it is also unpredictable in terms of drying time. With this in mind, boat yards can’t accurately bid a job and achieve an effective repair in a timely manner. It may take weeks to dry the core, compared to just removing the foam and finishing the repair in a few days. Without breaks, this repair took about 10 hours of labor, plus the cure time of the epoxy and drying the foam in the oven.

The repaired rudder looks good as new and is ready for paint. The owner of the rudder will not have an issue with water intrusion in the future.

To learn more about WEST SYSTEM products, and for free educational/instructional materials, visit westsystem.com .

Jacques Coon’s Drift Boat Build

Repairing Bow Damage on a Lightning Sailboat

Why Choose The WEST SYSTEM® Epoxy System?

GLUE U: THE BEST EPOXY EDUCATION

• Forum Listing
• Marketplace
• Advanced Search
• About The Boat
• Gear & Maintenance
• SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Injecting epoxy in wet core

• Add to quote

As I prepare to tackle the dreaded soft side deck repair, I am doing research on how to go about it. It seems this repair falls into 2 options. Drill and fill on small areas or cut and recore, on larger areas. How about this. Any one tried it?? Drill several holes around the damaged area. Install a 1/4 air male hose fitting in the middle of the area. Attach a hose and vacum pump. Leave sucking at low pressure and remove the moisture. Later on, intruduce thinned epoxy into the holes and draw it accross the area. Close the holes one by one as epoxy comes out of the vaccum pipe. Will air pass through the damaged area? Water already has. I have read many posts describing injection of epoxy with seringes,however they all rely on gravity and wicking to move the epoxy across the damaged area. A little help from a vacumm system surely would help draw and saturate the core faster. Is there such a system?? O.K. Let me have it. Thanks  

I've actually had this done on a boat of mine...on a drill and inject under pressure until the epoxy comes out the other hole(s) basis. It ONLY works on very small areas and is not a suitable approach for repairs to more than a few square inches. If you have larger areas of softness/wet core/delam...the only option is a complete removal of the laminate and core replacement.  

injecting the epoxy or resin sounds like it would work. My concern would be the water / moisture removal to in preparation for the repair. I've found exopy cures differently with alot of moisture present, like rain or soggy wood.  

Perfect type of repair for a de-lamination, but misses the point entirely for a rotten/ wet core. It won't work, sorry, all you will do is make a bigger mess to fix. If you are comfortable with vacuum bagging, tackle this repair from below, thickened epoxy to bond the new core to the underside of the deck, then use 3m 77 to hold the glass layers in place, 2 sets of hands will help. Set up your bag, and infuse. I use an old pressure cooker with an extra line plumbed in for the infusion line, then add air pressure to the cooker to aid in epoxy transfer. I also would use extra slow hardener, and consider chilling if the area is large. I think MAS has epoxy specifically for this, But I like the West personally. (old habits die hard) good luck  

CBlu... to be clear...I agree with you entirely...it is a temp solution suitable for stabilizing a very small area and the right way to do it is your way. Sometimes a quick fix is suitable from a a time and $$ standpoint...but it is not a cure.  

I vac. bagged my keel it was full of water and diesel and did injections it works , wanna see pics ???  

GREGGWARREN said: it was full of water and diesel and did injections it works , wanna see pics ??? Click to expand...

If your keel was full of water, and diesel, you did nothing. epoxy does not adhere to either. Of course this is my opinion, please prove me wrong.  

Core repair technicalyy this repair method could be very dodgy! why... 1. you have to ensure the core material is dry to a level of less than 5% "active water" throughout the entire 'damp area" and that the core material is not compromised. Injecting Low viscosity Resinsinto holes does not gaurantee you get resin to all the soft or "compromised areas of foam! NOR ITS POOR ADHESION WITH THE FIBREGLASS OUTER LAYER. Using a vacum pump combined with direct heat will drive out water but if salt water has been present you will leave salts (sodium) behind and thus the epoxy's adhesion will be compromised. Also fungal growth with fresh water could cause similar problems. You will also need to moisture probe (electronic)the core between holes to ensure no trapped water. 2. Injection of a low viscosity epoxy into the holes will not ensure total "gap filling" and will no resurrect the strength of the original lay up. Also the holes could be possible areas for further water ingress if not filled and sealed correctly. Also, low viscosity epoxys do not like high film builds! 3. Cutting out the effected area (from one side only, typically the underside ) and replacing the core using a angled cut of 8:1 for the foam joints followed be re instatement of the fibreglass using a tapered / feathered edge tehnique (12:1)is best and will maintain integrity of deck. 4. The only technology that could be injected into a hole or used in contact with moisture would be a moisture cured Urethane but the above still applies. And.. if your idea worked every boat builder (worth his salt) all over the planet would be doing it and i don't believe they are Hope this helps  

So how big is the area you are repairing? Would it be possible to just cut/router out this area and replace with marine ply (or whatever core material) and epoxy it in place?  

How big is the wet area? In my opinion, if you cannot remove all the wet core easily through a single small access hole then you're better off to cut open and recore it properly. The other problem with your plan is that if it doesn't work, and I think the consensus is that it won't, you have caused whoever does the future recore job (you) a great deal of work removing the skin to do it properly. Recoring is very hard to do properly from below and very messy. Vacuum bagging will help but still not necessarily a guarantee of successful bonding. The best way to a successful job is to do it from the top. While this means repair to deck coating - painting or non skid - it will also go much faster depending on the size of the wet area to be recored. Brian  

I recently went through this. I considered all options and after people pounded in "get rid of the bad", I decided to recore the area. I'm glad that I did because now I know that its solid. After carefully marking off, cutting and removing the top skin from the damaged area, I realized that the damage was larger and I had to keep cutting. I think that its typical to find that the damaged area is about 15% larger than you thought. Good luck.  

It's best to re-core because CPES does NOT displace water. The core has to be totally dry to use epoxy on it.  

I injected with 35 cc syring and large needle I cut short. I drilled with a tooth pick sized bit. i injected three times wih day cure between each. You could tell by drilling if voild. Some holes took 35 cc. More than 10 ounces would set before injected. Some would come out other holes I made. sure all 60 holes about 1.5 inch apart were filled. Sand and painted. i am sure it strong enough. Solid no give.  

I was just talking about this the other day with a friend. I was told (with no verification about this info), that if you use fast cure epoxy, you're likely to burn the boat down with the heat build up. Best to use slow cure and maybe do it on a cool day...  

You're not supposed to thin West System epoxy to make it penetrate. It will just weaken the epoxy. Use heat instead. Thinning WEST SYSTEM epoxy - Sailfeed  

Clearly replacing the core is the best option, but often is not logical in an older boat used for coastal cruising, where the cost of the repair could easily exceed the value of the boat. It's a lot of work, make no mistake. I have done the job and my repair is in an issue of Good Old Boat in 2004. I wouldn't do it again. First, why return an ancient deck to as new condition? Have you seen decks fail? In my 45 years of being around boats, I've never seen one failed deck. So ask yourself "what am I trying to achieve here"? If the core is not rotten epoxy injection is good. Very expensive yards use this as the method of choice, including Morris Yachts. It makes zero sense to rip out sound core to replace with more sound core. (Although many will happily charge you thousands of dollars to do just this). Acetone can be injected periodically until it's dry. Or you can use Boatlife Aquapoxy which cures well in wet wood. Size of the repair does not matter. Then inject unthickened epoxy. Do not thin it. If the deck core is rotten, you might consider injectadeck, which is a 2 part structural marine foam that remains liquid for the first 30 seconds or so, and penetrates into any cracks, crevices or gaps. It is attracted to moisture, and cures better in the presence of moisture. It then expands, and cures rock hard. Of course, you might get some small voids, but the deck I have seen repaired with this method is absolutely rock hard. Another approach might be the one taken by Aeromarine Industries, (see their video on deck repair). They inject structural foam between the overhead liner and deck, then epoxy into the dry deck core. This looks massively strong. If the core was wet and rotten, I'd use injectadeck into the core or Aquapoxy, but definitely not regular epoxy. None of these methods are perfect, but they do work, and can keep your boat going safely for many, many years. They are also about 1% of the work of replacing the core. Replacing the core would be an absolute last resort for me, and only if I planned to use the boat in extreme offshore conditions.  

I've done both - drill & fill falls into the same category as painting a rusty car before selling it. You can vacuum out the liquid water but everything is still wet. It just plain doesn't work.  

Well, a painted rusty car will show the rust again in a few weeks. There are epoxy injected decks going strong after 20 years. Hardly the same thing. Yours may have failed, but it can and does work in many cases. As I mentioned, it is used by excellent yards and recommended in certain cases by the Goudgeon Bros. Take some wet, rotten wood. Put it in a plastic or aluminum tray. Pour aquapoxy over it, until covered. In a day or two, you will have rotten wood encapsulated in rock hard epoxy. I'm not saying it's a good as replacing the deck. Far from it. But it definitely does often work, it adds structural rigidity, lasts a long time, and makes the most sense for may boats. Of course, a quick and dirty job probably will fail. Like blister repair, many self-proclaimed experts will advise you on repairs far, far in excess of what is warranted or logical.  

I recored about 16 square feet with 1/2" endgrain balsa. Didn't think it was an expensive or difficult job compared to other boat jobs. In fact just the opposite, was pretty cheap and easy. Hell cost me more for two batteries and a new smart charger for them. Not saying it isn't a bit messy and lots of sanding filler but it isn't actually difficult, unless you failed cut and paste in kindergarden....  

If you inject epoxy into core that is wet it will cure. It will stick to dry areas but not wet areas. It will make a proper repair by the next owner a nightmare.  

Dug into "Band-Aid" repairs far too many times. Very, very frustrating.. There are no miracle cures to repairing wet decks, that I've torn into yet, that are worth much of anything other than to make the correct repair a complete nightmare. Products such as those mentioned above in this thread, eg: expanding PU foams etc., are relatively new and yet remain unproven over the long haul. Most of them lack structural testing data or cut-a-ways showing it to actually do what the marketing claims it will. There are thousands of hurricane damaged boats with wet-decks that can be injected then cut open to see how these products actually work but I've searched high and low and these tests, and cut-a-ways, don't exist that I've found. As a marine professional I would welcome such a product but so far every method I've seen tried, other than cutting the deck open and re-building it, has failed to do what it claimed it could. They only made future repairs a bigger nightmare. Perhaps someone has a link to some structural third party testing data and cut-a-way images of repaired wet decks using some of these products?  

The previous owner of my boat repaired some soft spots on the deck with Gorilla Glue. Gorilla glue cures with water. He injected the glue into several holes drilled in the areas. The directions for the glue say to wipe both surfaces with water before spreading glue. The areas he repaired seem sound with no indication of softness.  

• ?            
• 176.5K members

Top Contributors this Month

• 2024 BOAT BUYERS GUIDE
• Email Newsletters
• Boat of the Year
• 2024 Freshwater Boat and Gear Buyers Guide
• 2024 Boat Buyers Guide
• 2024 Water Sports Boat Buyers Guide
• 2024 Pontoon Boat Buyers Guide
• Cruising Boats
• Pontoon Boats
• Fishing Boats
• Personal Watercraft
• Water Sports
• Boat Walkthroughs
• What To Look For
• Watersports Favorites Spring 2022
• Boating Lab
• Boating Safety
• Ultimate Boating Giveaway

Dryboat Treatment for Wet Hull Core

• By Kevin Falvey
• Updated: January 25, 2019

Tim put his meticulously maintained 10-year-old 36-foot sport-fisher up for sale last spring, and he soon found an eager buyer.

All that remained was for the boat to pass the survey, and the money — a down payment for his next boat — would be Tim’s to spend.

It failed. The surveyor discovered wet hull core with a moisture meter, and subsequently pulled hull fittings and portholes to physically reveal the wet balsa core. Tim returned the deposit to the buyer, who left angry. And he was stuck with $95,000 worth of unsaleable boat.

Learn About Different Hull Construction Types

Of course, he might have been able to sell the boat at a fire-sale price, but that would have meant walking away from many tens of thousands of dollars. Plus, “I wanted to sell the boat with a clean conscience,” Tim says. Traditional methods for dealing with wet core, including cutting, chiseling, replacing and reglassing, can also cost $40,000 to $50,000 or more. Not to mention the destructive damage such measures incur. Ugh!

How-To Drill Into and Install Accessories in Cored Hulls and Decks

Enter Dryboat. This Michigan-based moisture-remediation firm offers a mobile, nondestructive system to dry out cored fiberglass boats. According to company president Scott Richmond and developer Jon Bartnick, the process restores the affected areas to moisture levels acceptable by the builder. It is the only method they know that maintains the original design of the manufacturer, as well as the structural integrity of the affected vessel.

I saw it in action. In simple terms, the first step is to determine the extent of the moisture intrusion, using a moisture meter, and by mechanically removing fixtures and drilling exploratory holes. Next, a series of holes, sized to fit the application, is drilled. Into these are inserted hoses connected to the system, which is housed in a trailer and runs 24/7 until the boat is dry. All of this, plus the price, varies from job to job, depending on circumstances. For Tim’s boat, it took a month and “$1,000 worth of electricity, though the weather was very damp when we started, which lengthened the drying time,” Tim explains.

Read Next: Inspecting Your Boat’s Finish

Once the structure is dry, the holes need to be repaired and repainted or regelcoated. Tim, an auto-body man, did that work himself. And his business’s yard provided a space to run the equipment all the time without extra cost or complaints.

Tim’s Dryboat bill was $13,000. His boat passed the survey, and he sold it for $85,000. Subtracting the $15,000 he’d spent on remediation, that netted him $70,000. He was happy with that, given the expense of the alternatives, plus “I sold it with a clear conscience,” he says.

More Information Dryboat – 855-379-2628; dryboat.com

Five Tips For Preventing Wet Core In Your Boat’s Structure

The boater in this story was caught by surprise. He didn’t realize his boat’s hull core was soaking wet until a marine surveyor turned it up during a pre-purchase inspection arranged by a potential buyer. To help avoid a similar situation yourself, take these five proactive and precautionary measures.

Learn the proper way to install accessories in cored hulls and decks . Whether you are adding a transducer, an antenna; replacing a hatch; or repairing a bowrail stanchion, the procedure for cutting and drilling holes in cored laminate are more complex than the techniques that apply to solid fiberglass. Basically, the cutout must be sealed as well as sealing the fitting

Pull through-hull fittings, engine mounting bolts and other penetrations on a periodic basis in order to inspect the core and make sure water is not getting in.

Reseal fittings and fixtures regularly. We can’t give you a specific time frame for this, because different caulks and different environmental conditions, result in the need to re-seal or re-caulk at different rates. Bottom line, caulk isn’t forever, so pull and reseal fuel fittings, engine bolts, antenna mounts, rail stanchions…..any fitting that passes through or into the core or that is fastened through or into the core—needs to be resealed regularly.

Buy a moisture meter and use it if you have a cored hull. These can be had for as little as $250. Of course, if you don’t want to buy a meter and learn how to use it, you can always hire a marine surveyor to check your boat’s core material for moisture periodically.

Inspect your boats finish for irregularities and flaws that might indicate structural concerns.

• More: boat maintenance , How-To

More How To

How to Get Sand out of Your Boat’s Carpet

Unwritten Boat Ramp Rules

The Importance of Trailer Safety Checks

Compounding Mistakes Make for a Dangerous Situation

The History of Ski Nautique

The Basics of Lithium Marine Batteries

Nimbus Group Partnership With Nautical Ventures Expands EdgeWater Dealer Network Across Florida

Humminbird Mega Live Hand Control

• Digital Edition
• Customer Service
• Privacy Policy
• Terms of Use
• Cruising World
• Sailing World
• Salt Water Sportsman
• Sport Fishing
• Wakeboarding

Many products featured on this site were editorially chosen. Boating may receive financial compensation for products purchased through this site.

Copyright © 2024 Boating Firecrown . All rights reserved. Reproduction in whole or in part without permission is prohibited.

Log in or Sign up

You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser .

Hull major soft spot repair

Discussion in ' Fiberglass and Composite Boat Building ' started by fleix , Jul 4, 2019 .

• delamination

fleix Junior Member

Hi guys, Currently I’m trying to safe my beloved Shark24 from the chainsaw. She is a small sailboat of 2100 lbs. (950 kg) build in the early 90s. The hull is a 100% hand laid fiberglass laminate with a thickness of about 0.2’’ (5 mm). The deck and the inner shell are partially built with an unknown foam core. The hull suffers from some large soft spots. The weakest area is located in front of the first bulkhead from astern. The main stringers are connected to this bulkhead. These stringers are made out of hollow fiberglass. I am concerned the stringers were not placed right by the boatyard, because there is a gap between stringer and hull. The only connection is some layers of fiberglass along the stringers. I was told usually the stringers were bedded in thickened resin so there shouldn’t be any gap. People told me to cut my boat into pieces, but I want to safe her badly. I’ve put a lot of effort into fixing the soft spots at the bow and I want to teach my kids how to sail on this boat, as my grandfather taught me on her before. Some advice how to fix this would be greatly appreciated. I’m not in rush my son still needs three years to learn to swim so I don’t care if a repair takes a lot of time/effort. A picture paints a thousand words, so here are some photographs, a small sketch of a cross section and parts of the construction plan of the boat from the early 60s. I have grinded away parts of the fiberglass along the stringer as you can see in the before-after-pictures. The hull laminate underneath the stringers is so soft, that I can push it from the outside against the stringer / inner shell without any pressure. Please bear with me if my English isn’t perfect. I’m not a native speaker. starboard connection of the stringer (before) inner section of the stringer / inner shell (before) overview starboard bulkhead and stringer (after) starboard stringer / hull 0.4" gap (after) starboard stringer / hull 4.7" depth (after) cross section plan #1 plan#2  

trip the light fandango Senior Member

Hi Fleix, and welcome, I suspect your yacht is plywood sheathed in fibreglass. If so it is probably best to buy another Shark that is 100% fibreglass and use your parts., because the rot will keep creeping up. If your boat is all fibreglass screw or bolt and resin the stringers back down, sand and clean the whole soft area and glass it up with a good quality woven mat, remove the screws and fill the holes with glass fibre and resin. And good luck. PS. I just read Blueknarr,, .. so then relaminate inner skin to outer every corner of a 200mm grid cutting 50mm squares[or round] through the foam for the joins in the area affected is how I think I would do it,. cheers  

Blueknarr Senior Member

Welcome Bad news and fatal prognosis: you're emotionally attached to a sailboat. The good news: its design has a proven great track record. Solid wood stringers need to be fully bedded. Box stringers, like yours, are not bedded and utilize tabbing as part of their structure. The foam interior's sole purpose is to suspend the wet FG until the resin cures. Why your vessel is plagued with delamination is a mystery that probably won't be solved. My guess is that a stack of core foam was contaminated. Have you found and fixed the last of the delamination? I certainly hope so. Is your emotionally attachment to this boat fatal? Well we all must have our flaws. You fixed the other delamination, your work so far on this one looks excellent. You know what needs doing. Take care and be proud of passing on a legacy that your children will enjoy.  

Thank you for your response! My shark is about 100% fiberglass. Only the bulkheads are made out of plywood. There is no foam either in the stringers so luckily there is no rot at all. Foam core was used exclusively in the deck and some parts of the inner shell but not at the stringers. The hull is build out of pure fiberglass and polyester. From my point of view there never was a real connection between the hull and the stringer only this tiny strip of laminate which is marked orange in the cross section. So I don’t think bolting the stringers down would be the right way to repair this. I’ve attached a picture of the inner shell of a newer shark. The shell is upside-down and you have a good view of the stringers. My boat was build similar to this version. In the second picture I’ve marked the edges of the stringers. Between the red marked edges and the hull there is a gap of 10 mm. I was told by someone who refitted over 5 sharks that this gap shouldn’t be there. He said originally the stringers were bedded in thickened polyester and it appears that in my case the boatyard just forgot it / was too lazy. I have also marked the inner edges of the stringers green. I have no idea if or how they are bond to the hull. In the original plans of the shark there wasn’t any gap at all between stringer edge and hull, so they were only connected by tabbing. Apparently they had troubles fitting the inner shell to the hull so they used thickened polyester to fill the gaps. From my point of view the way my shark was build created some hard spots which led to the delamination. I’ve marked this in the cross section. I haven’t fixed the delamination of the stern yet. I have to open the inner shell first to reach the hull. I want to do two cuts along the cross section. One cut close to the bulkhead and the other one as close to the front as possible, which is about 100 cm of the bulkhead. I hope to get this part of the inner shell out in one piece. Afterwards I hope to get a good overview of the mess and have enough space to grind down the damaged laminate and build up a new one. Following this, I’m planning to fill all the gaps between the edges of the stringers and the hull and finally get back the cutout, place it in thickened epoxy and laminate it back in. Yes I’m emotionally attached to this boat but I’m not completely naive. I’m giving my best to fix it. If that’s not enough I will keep on sailing her until she falls apart. The boat is rock solid around the keel, the mast and the chain plates. If this wouldn’t be the case I wouldn’t bother fixing it. Inner shell / stringers cross section: left current situation, possible hard spots. right possibility to fix it?  

Too bad the warranty has long sense expired. How did you get that incert out in one piece?!? I agree that the incert was not installed correctly. It didn't prevent the hull from flexing. As the hull flexed it tugged on the inner skin where or was semi attached and caused the inner skin to delaminate. If you also have hard spot issues; they will be manifested as cracks in the outer skin at and parallel to the stringers. Your solution is mostly sound. I would be hesitant to reuse old inner skin. It would be easy to insufficiently tie it to the undisturbed skin and have voids under it. Keep up the good work  

Thank you for you encouragement! I didn't get the inner shell out. It's a picture of another shark being build in Poland at the new home of the shark mould. The hull suffered from many cracks in the bow area along the stringers because they weren't bond properly to the hull. This boat must have been put together on a Friday evening... The boatyard produced only a few sharks before the mould switched places again.  

Friday evening ... or Monday morning after a three-day week end.  

Steve Clark Charged Particle

So is the flexing due to the hull skin becoming detached from the stringers? Or is is a bigger problem, like the hull laminate sheering in two. Resulting in two thin laminates next to each other instead of one thick laminate. To find out, you kind of have to cut a piece out and see if the sample is one or two pieces. SHC  

fallguy Senior Member

fleix said: ↑ Thank you for your response! My shark is about 100% fiberglass. Only the bulkheads are made out of plywood. There is no foam either in the stringers so luckily there is no rot at all. Foam core was used exclusively in the deck and some parts of the inner shell but not at the stringers. The hull is build out of pure fiberglass and polyester. From my point of view there never was a real connection between the hull and the stringer only this tiny strip of laminate which is marked orange in the cross section. So I don’t think bolting the stringers down would be the right way to repair this. I’ve attached a picture of the inner shell of a newer shark. The shell is upside-down and you have a good view of the stringers. My boat was build similar to this version. In the second picture I’ve marked the edges of the stringers. Between the red marked edges and the hull there is a gap of 10 mm. I was told by someone who refitted over 5 sharks that this gap shouldn’t be there. He said originally the stringers were bedded in thickened polyester and it appears that in my case the boatyard just forgot it / was too lazy. I have also marked the inner edges of the stringers green. I have no idea if or how they are bond to the hull. In the original plans of the shark there wasn’t any gap at all between stringer edge and hull, so they were only connected by tabbing. Apparently they had troubles fitting the inner shell to the hull so they used thickened polyester to fill the gaps. From my point of view the way my shark was build created some hard spots which led to the delamination. I’ve marked this in the cross section. I haven’t fixed the delamination of the stern yet. I have to open the inner shell first to reach the hull. I want to do two cuts along the cross section. One cut close to the bulkhead and the other one as close to the front as possible, which is about 100 cm of the bulkhead. I hope to get this part of the inner shell out in one piece. Afterwards I hope to get a good overview of the mess and have enough space to grind down the damaged laminate and build up a new one. Following this, I’m planning to fill all the gaps between the edges of the stringers and the hull and finally get back the cutout, place it in thickened epoxy and laminate it back in. Yes I’m emotionally attached to this boat but I’m not completely naive. I’m giving my best to fix it. If that’s not enough I will keep on sailing her until she falls apart. The boat is rock solid around the keel, the mast and the chain plates. If this wouldn’t be the case I wouldn’t bother fixing it. Inner shell / stringers cross section: left current situation, possible hard spots. right possibility to fix it? Click to expand...

I am a little confused. Perhaps I am missing something. In the picture of your cross section, you clearly show the soft section, but you don't show a repair going from the soft section to 'hull intact' on the sides. Perhaps your drawing is not showing the verbage, but I don't understand how you expect to succeed only fixing the bottom if the soft section extends up to the sides. And it is late and I am a bit tired.  

tpenfield Senior Member

Not sure I understand if the hull is soft on the inside (because of the inner liner), or soft on the outside (because the hull itself is too thin).  

tpenfield said: ↑ Not sure I understand if the hull is soft on the inside (because of the inner liner), or soft on the outside (because the hull itself is too thin). Click to expand...

Tanks for your replies. Steve Clark said: ↑ So is the flexing due to the hull skin becoming detached from the stringers? Or is is a bigger problem, like the hull laminate sheering in two. Click to expand...

• Advertisement:

I'm thinking that if you had 5 mm (0.2") of good, "solid" fiberglass, then it should not feel soft. Just wondering what you will find as you start grinding into the hull from the inside ( areas of dry fiberglass maybe ?) If I were doing the work, I'd want to know more about why that area of the outer hull is soft to begin with. Do you have any pictures to share of the work that you did on the bow section?  

Making a Hull Narrower

How to make a hull in epoxy and fiberglass only from a mold — no vacuum

Hull separation

Extended hull, extend strakes?

Reglassing 50' cat hull bottoms - overhead?!

How to proceed after hull extension mold error.

Hull thickness requirements different materials

Hull construction composition (where to stop grinding).

Hull insulation

Splitting deck and hull on Mastercraft X-Star

• No, create an account now.
• Yes, my password is:
• Forgot your password?

• New Sailboats
• Sailboats 21-30ft
• Sailboats 31-35ft
• Sailboats 36-40ft
• Sailboats Over 40ft
• Sailboats Under 21feet
• used_sailboats
• Apps and Computer Programs
• Communications
• Fishfinders
• Handheld Electronics
• Plotters MFDS Rradar
• Wind, Speed & Depth Instruments
• Anchoring Mooring
• Running Rigging
• Sails Canvas
• Standing Rigging
• Diesel Engines
• Off Grid Energy
• Cleaning Waxing
• DIY Projects
• Repair, Tools & Materials
• Spare Parts
• Tools & Gadgets
• Cabin Comfort
• Ventilation
• Footwear Apparel
• Foul Weather Gear
• Mailport & PS Advisor
• Inside Practical Sailor Blog
• Activate My Web Access
• Reset Password
• Customer Service

• Free Newsletter

Dufour 44 Used Boat Review

Blue Jacket 40 Used Boat Review

Catalina 270 vs. The Beneteau First 265 Used Boat Match-Up

Ericson 41 Used Boat Review

How to Create a Bullet-Proof VHF/SSB Backup

Tips From A First “Sail” on the ICW

Tillerpilot Tips and Safety Cautions

Best Crimpers and Strippers for Fixing Marine Electrical Connectors

Revive Your Mast Like a Pro

Solving the Dodger Dilemma

Polyester vs. Nylon Rode

Getting the Most Out of Older Sails

Sailing Triteia: Budget Bluewater Cruising

How To Keep Pipe Fittings Dry: Sealant and Teflon Tape Tests

Fuel Lift Pump: Easy DIY Diesel Fuel System Diagnostic and Repair

Propane Leak: How to Detect, Locate and Fix

Why Choose the Wharram Design?

Winterizing: Make It Easy With Checklists

Stopping Holding-tank Odors

Giving Bugs the Big Goodbye

Galley Gadgets for the Cruising Sailor

The Rain Catcher’s Guide

Sailing Gear for Kids

What’s the Best Sunscreen?

UV Clothing: Is It Worth the Hype?

Preparing Yourself for Solo Sailing

R. Tucker Thompson Tall Ship Youth Voyage

On Watch: This 60-Year-Old Hinckley Pilot 35 is Also a Working…

On Watch: America’s Cup

On Watch: All Eyes on Europe Sail Racing

Dear Readers

• Boat Maintenance

A Stronger Screwhole Repair

Need to re-use an old screw hole stuff it with resin and cloth..

The fastest way to attach light hardware to a cored deck is a self-tapping screw. It is also the fastest way to have hardware rip out of the deck and end up with a wet core and delaminated deck. But how to replace screws that have gotten loose or prevent a wet deck in your future? One method is to drill and over-sized hole, remove some core, fill the enlarged hole with epoxy, and then replace them with small through bolts (see Spreading the Load Practical Sailor, August 2016 ). But what if the backside is inaccessible? Can we create an improved repair by filling and reinstalling a self-tapping fastener, without major surgery? What sealing and filling material is best?

Photos by Drew Frye

What We Tested

Neat epoxy, epoxy thickened with sawdust, micro-balloons, colloidal silica were used to fill test holes. We also stuffed fiberglass cloth into holes and tested solid materials for comparison. We used #8 sheet metal screws and drilled and plugged the same -inch cored deck samples fabricated for prior PS testing of backing plates and washers. The panel consists of a 1/2-inch balsa core with skins hand laid from three-layers of 17-ounce triaxial fiberglass cloth, using West Systems epoxy.

How We Tested

We drilled 7/16-inch holes through the top skin and core only. We then inserted a modified roofing nail cutter that removed the core and additional 5/32-inch of core from under the skin.

Holes were then filled with West Systems Epoxy using slow hardener. Additional holes were filled with the same epoxy thickened with either sawdust, West Systems micro-balloons, or Cabot M-5 colloidal silica (also called cabosil, or fumed silica). One set was filled with epoxy after which it was stuffed full of 6-ounce fiberglass cloth. Screws were fastened while the material was curing, establishing an adhesive bond as well as a mechanical bond.

Additionally, screws were also set in the skin-only, a pine board, and solid fiberglass sheet for comparison. In all cases, a pilot hole matching the core diameter of the screw was used.

Observations

Use slow epoxy systems. The plug is large enough for West Systems Fast Hardener (205) and all 5-minute epoxies to build heat and make bubbles (exotherm). This results in a weak plug.

Fill holes when the temperature is steady or falling. If a cored structure is filled when the temperature is rising, expanding air will come out through the hole, creating bubbles and a weak plug.

It was obvious which systems would be strongest as soon as we drilled the pilot holes. The neat epoxy and epoxy plus fiberglass holes offer some resistance, whereas those using fillers drilled without effort.

The generally poor performance of fillers derives from a variety of factors. In the case of sawdust and micro-ballons, they are fundamentally weak. In principle, epoxy thickened with colloidal silica should be 10-30 percent stronger, stiffer, and harder than straight epoxy. In fact, however, the presence of fillers increases retention of micron-sized air bubbles, originating from the air trapped within the filler itself.

The only way those high-strength promises can be delivered is when the powder and epoxy are blended under full vacuum, eliminating the air, not a possibility for the DIYer. As a result, all epoxy-filler blends are loaded with microscopic air bubbles. These bubbles reduce strength when bonding, and more dramatically when we cut through them in the process of making threads. Pre-blended epoxy putties, such as Marine-Tex and JB Weld are even weaker.

Fiberglass cloth also retains some air, but these bubbles can be worked out with a little gentle prodding, just as you work air out of hand laid fiberglass laminate with a roller. They are not the microbubbles that make thickened epoxy opaque. Fill the hole with epoxy before adding the cloth; this ensures the cloth wetted out and minimizes trapped air.

We were surprised by just how much glass we could cram into an over-sized hole. With just a few moments effort, 15 square inches 6-ounce fiberglass cloth-nearly 1/5 of a sheet of paper-could be crammed into a hole only -inch deep and 5/8-inch in diameter. The glass fibers add both strength and toughness.

Skin-only threads, without an epoxy plug is weak and invites water penetration to the core in exterior repairs. Testing in solid fiberglass reaffirmed a rule of thumb we developed from testing bolts tapped into solid fiberglass; so long as the solid glass is at least two fastener diameters thick, the fastener will fail before stripping. This was also reaffirmed when we witnessed fiberglass-reinforced plugs being pulled right through the skin.

This is asking for a wet core and should only be practiced in dry areas. Strength depends entirely on the original layup and is poor, even for light duty use.

Bottom line: For interior use only.

Plain Epoxy

Straight epoxy is brittle, so it was no surprise when the plug failed by cracking. But it should also be noted that this didnt happen until the load was pretty high, much higher than a fastener this size should be expected to hold. Neat epoxy is easier to work with and easily place in the hole with a syringe. On vertical surfaces masking tape can be used to keep it in place.

Bottom line: Recommended for general use.

Epoxy plus Saw Dust

We thought it might reduce cracking, but it was just weak.

Bottom line: Not recommended.

Epoxy Plus Micro Balloons

Light fillers have real advantages when working on vertical surfaces. They don’t sag. They are also easier to sand when fairing. However, they are weak and don’t hold threads.

Bottom line: Micro-balloons are for fairing, not adding strength.

Epoxy plus Colloidal Silica

Infamous for difficulty in sanding, colloidal silica is used for thickening bonding fillets and where high compressive strength is needed. We were surprised that it didnt hold threads better, until we looked at some samples with a microscope. Although micro-bubbles probably have little effect on macro bonding, they do appear to undermine the structural strength required when re-setting a screw.

Bottom line: Not for cut threads or self-tapping screws.

Epoxy plus Fiberglass Cloth

Fill the hole with neat epoxy. This eliminates the challenge of wetting the glass and getting the epoxy clear to the bottom. Cut a strip about 1-inch wide and 15 inches long, and cram it into the hole using a blunt instrument, such as the dull end of a cooking skewer. During the cramming process most of the bubbles will be displaced, but you will still need to poke and top off for a few minutes to coax the stragglers out. The epoxy should stand proud above the surface and there will be fibers sticking out the top; just sand them off when cured. While this all takes a few extra moments, the results are worth in high load applications.

Bottom Line: Best Choice when strength matters.

Solid Fiberglass

So long as the glass is at least twice the fastener diameter, it should hold the full strength of the fastener. However, repeated removal will damage the threads. Drill the correct pilot hole size or the fastener will bind and break.

Bottom line: Screws will hold in solid glass, but they are not nearly as reliable as a bolt and nut.

Conclusions

Any filler reduces the ability of the epoxy to hold threads. It does this primarily by forming microscopic air bubbles that have no chance of escaping the thickened epoxy. This does not imply that the compressive strength or bonding strength has been reduced-colloidal silica is valid for through bolt and filet bonding applications. But it will fail in the tiny spaces around threads. Neat epoxy is brittle and prone to cracking; however, this did not reduce the strength much and is perfectly suitable for sealing holes for through bolts and most self-tapping screw applications.

The highest strength option, it turns out, is reinforcing the epoxy with fiberglass cloth. This combines the strength and bubble-free consistency of epoxy with the toughness and high strength of fiberglass, yielding the highest possible strength. In every test, the plug pulled out before the threads stripped. But are you better off with a stripped screw or a thumb-sized hole in the skin of the deck? You will have to answer that question, based on the nature of the installation.

For this comparison, testers combined West Systems epoxy (with a slow hardener) and various thickeners to find the strongest combination. In one hole, no thickener was used. Three holes were filled with epoxy thickened with: 1) sawdust; 2) West Systems micro-balloons; and 3) Cabot M-5 colloidal silica. The fifth hole was filled with epoxy and then stuffed with 6-ounce fiberglass cloth. Screws were fastened while the material was still curing.

• We drilled 7/16-inch holes through the top skin and core only.
• An ordinary twist tie is used to force the fiberglass into the hole, which is already saturated with resin.
• One of the holes was filled with unthickened epoxy and allowed to cure.
• Our pull test apparatus was simple but effective. Testers pulled until the screw breaks or lets go, and recorded the load on the dynamometer (above and out of the picture).
• A microscope reveals the bubbles forming inside the epoxy thickened with silica. These bubbles weaken the matrix, making it easier for screws to pull out under load.
• The cohesive bonds in the cured unthickened epoxy gave out before the screw stripped out the threads. Notice the threads are still visible inside the repair.
• The balsa core split and tore through the fiberglass skin, providing the strongest repair.

RELATED ARTICLES MORE FROM AUTHOR

Leave a reply cancel reply.

Log in to leave a comment

Latest Videos

A Sailboat Tour of the Exquisite Little Harbor 63 Ketch

Dock and Anchor Lines – Polyester or Nylon?

The Performance Sailboat from Island Packet: Blue Jacket 40 Boat Review

Top 3 Winter Boat HACKS!

Latest sailboat review.

• Privacy Policy
• Do Not Sell My Personal Information
• Online Account Activation
• Privacy Manager

• CREATE AN ACCOUNT
• Boat Cover Finder
• Bimini Top Finder
• Boat Propeller Finder
• Engine Parts Finder
• Anchor & Dock
• Watersports
• Clothing and Footwear
• Engine Parts
• Cabin and Galley
• Covers and Biminis
• Electronics
• Paint and Maintenance
• Pumps and Plumbing
• Anchor Chains & Ropes
• Boat Fenders
• Boat Mooring
• Boat Protection
• Dock Storage & Protection
• Ladders, Steps, & Platforms
• Top Sellers

• Fishing Rods
• Fishing Reels
• Fishing Rod & Reel Combos
• Fishing Tools & Tackle Boxes
• Fishing Line
• Fly Fishing
• Fishing Bait & Fishing Lures
• Fishing Rod Holders & Storage Racks
• Fish Finders, Sounders & Sonar
• Trolling Motors
• Fishing Nets
• Fishing Downriggers & Acessories
• Fishing Outriggers & Acessories
• Fishing Kayaks
• Fish Cleaning Tables

• Inflatable Rafts
• Paddle Boarding
• Paddles & Oars
• Wakeboard, Wakesurf & Ski
• Wakeboard Towers
• Tow Ropes & Handles
• Life Jackets & PFDs
• Snow Sports
• Roof Racks, Carriers, Dollies

Men's Clothing

• Accessories

Men's Footwear

• Atheltic Shoes
• Water Shoes

Women's Clothing

• Dresses & Skirts

Women's Footwear

• Fuel Systems
• Sacrificial Anodes & Zincs
• Generator Parts
• Inflatable Boats
• Propeller Parts & Accessories
• Boat Manuals
• PWC Parts & Accessories

• Fishing Boat Seats
• Offshore Boat Seats
• Ski Boat Seats
• Pontoon Boat Seats & Furniture
• Boat Seat Pedestals & Hardware
• Boat Seats by Manufacturer
• Boat Tables & Hardware
• Boat Seat Covers
• Boat Seat Vinyl
• Floating Boat Cushions

• Barbeque Grills
• Boat Drink Holders
• Cabin Accessories & Hardware
• Boat Ventilation
• Interior & Cabin Lighting
• Marine Teak Products
• Carbon Monoxide & Smoke Detectors
• Binoculars & Telescopes

Boat Bimini Tops

• Bimini Top Accessories
• Pontoon Bimini Tops
• Other Biminis
• RV & Trailer Covers
• Boat Shrink Wrap & Accessories
• Boat Shelters

Boat Covers

• Boat Cover Accessories
• Boat Lift Canopy Covers
• Other Covers
• Boat Wiring & Cable
• Marine Batteries & Accessories
• Marine DC Power Plugs & Sockets
• Marine Electrical Meters
• Boat Lights
• Marine Electrical Panels & Circuit Breakers
• Power Packs & Jump Starters
• Marine Solar Power Accessories
• Marine Electrical Terminals
• Marine Fuse Blocks & Terminal Blocks
• Marine Switches
• Shore Power & AC Distribution

• Marine Audio & Video
• GPS Chartplotters & Accessories
• Electronic Navigation Charts & Software
• Digital Instruments
• Display Mounts
• VHF Radios & Communication
• Marine Radar
• Auto Pilot Systems
• Action Cameras

• Fiberglass & Epoxy Boat Repair
• Boat Paint & Varnish
• Marine Adhesives, Sealant, & Caulking
• Marine Engine Maintenance
• Boat Cleaners & Waxes
• Boat Cleaning Supplies

• Fresh Water Boat Systems
• Bilge Pumps
• Marine Plumbing Parts
• Wash Down Pumps
• Livewell Aerator Pumps & Live Bait Wells
• Toilet & Waste Pumps
• Marine Pump Replacement Parts

• Tires, Rims, & Hub Kits
• Boat Trailer Winches
• Boat Motor Supports & Transom Savers
• Boat Trailer Guides & Rollers
• Boat Trailer Fenders
• Boat Trailer Lights
• Boat Trailer Hardware
• Boat Trailer Jacks
• Boat Trailer Brakes & Axles
• Boat Trailer Tie Downs
• Couplers, Mounts, Hitches, & Locks

• Boat Deck Harware
• Marine Nuts, Bolts, & Screws
• Boat Handles, Pulls, & Rings
• Prop Nut Kits & Hardware
• Boat Cabin Hardware
• Marine Fasteners
• Boat Windshield Parts
• Boat Tubing & Rails
• Boat Mirrors
• Marine Tools & Tool Kits
• Boat Lettering

• Women's Clothing Deals
• Men's Clothing Deals
• Fishing Deals
• Anchor & Dock Deals
• Electrical Deals
• Electronics Deals
• Paint & Maintenance Deals
• Pumps & Plumbing Deals
• Boat Seats Deals
• Trailering Deals
• Camping & RV Deals
• Dealer Login

• Forums Login

• Search forums
• The iboats forum moderators are excited to announce that at this time it appears the iboats forums posting pictures function is working once again. Though we cannot promise for how long, we're hoping for indefinitely.
• Boat Repair and Restoration
• Boat Restoration, Building, and Hull Repair

Injection repair of wet balsa core

• Thread starter Simplesailor
• Start date Jan 25, 2014

Simplesailor

• Jan 25, 2014

If this is a dupe, I apologize but my earlier post doesn't seem to have made it! I have discovered that water is entering the core of the coach roof on my 30 ft Nonsuch sailboat through failed bedding on the roof hatch. I plan to replace the hatch. So far there is no noticeable damage to the fiberglass around the hatch but a moisture meter shows that the core immediately around the hatch is wet. I have been told that wet core can be stabilized and the area strengthened by injecting Caviseal or some other substance into the area between the fiberglass layers. I am interested in any personal experiences with this type of repair. What did you use and how did you apply it, any lessons learned, etc.? Thanks  

• Jan 26, 2014

Simplesailor said: If this is a dupe, I apologize but my earlier post doesn't seem to have made it! I have discovered that water is entering the core of the coach roof on my 30 ft Nonsuch sailboat through failed bedding on the roof hatch. I plan to replace the hatch. So far there is no noticeable damage to the fiberglass around the hatch but a moisture meter shows that the core immediately around the hatch is wet. I have been told that wet core can be stabilized and the area strengthened by injecting Caviseal or some other substance into the area between the fiberglass layers. I am interested in any personal experiences with this type of repair. What did you use and how did you apply it, any lessons learned, etc.? Thanks Click to expand...

Seaman Apprentice

• Jan 27, 2014

Re: Injection repair of wet balsa core I've injected thickend resin in dried out soft plywood as a last option before. The boat had been drying for a couple of months before I drilled holes and injected polyester thickend with microglass balloons. The area got much stiffer, but some hard spots can be felt if you know what too look for. I've also helped a friend do the same on his 33' sailboat where the balsa was rotted out under a winch. If I would do it again I would use epoxi instead but same procedure.  

Woodonglass

Supreme mariner.

• If the core is not rotted, it can be dried out. To determine if the core is rotted, get at the back side of the laminate and drill a grid of 1/8” holes in a 1” checkerboard arrangement. Of course you are not drilling through both sides of the laminate. Drill only through the inside. Do this over the entire area that has a moist core. To get a neat, consistent pattern of holes I apply sticky back cabinet shelf paper. It comes in a checker board design.
• Clean out the flutes of the drill every few holes. Unrotted balsa will have no smell or smell like resin and it will be fibrous when you roll it in your fingers. Rotted balsa will smell moldy and have more of a mushy or dusty feel. If you are really unsure, drill a ?" hole and pick some of the balsa fibers out with a tweezers. Rotted fibers will crumble or mush. Good balsa will be much harder to remove and it will be very fibrous.
• If you are lucky enough to live in a northern climate, where the temperature moves above and below freezing in the spring and the fall, nature will dry the laminate after you’ve drilled the hole grid described above. Here, ice crystals form as the temperature drops and the moisture is driven out of the wood. Ever look at a loaf of freezer burnt bread with ice crystals collected in the plastic bag? This occurs when the temperature inside the freezer fluctuates above and below freezing. What you want is a freezer burnt core in your boat.
• If you are not in a northern climate, or worse you are in a high humidity climate, I cannot help you. Text books talk about injecting alcohol, using tents and halogen lights but I have not used these methods.
• If the core is rotted, you need to fix it or the lack of core support will lead to much bigger problems. The question is when can you use simple injection versus tearing out the rotted area and replacing it?
• If the upper and lower fiberglass layers are structurally sound, the core can be repaired with injection. If the fiberglass does not show stress cracks or obvious hydrolysis (blisters or milky looking fiberglass), it will be fine.
• Large areas with stress cracks may be repaired with injection but I have not done that so I cannot predict the success. However, I can tell you this. I did do what was to be a temporary repair to a 30 foot Pearson Flyer that had a 6 inch crack in the hull. The outer hull had been punctured from a bad cradle pad. That was 10 years ago. When we injected the polyurethane from inside the hull, the polyurethane oozed out of the hull crack on the outside and then set up. The intent was to do a permanent repair after the racing season ended. A final repair was never done because the area around the temporary repair is stronger than the surrounding original hull.
• If she is a racing boat without a headliner the air holes can be left unsealed. But if a headliner is installed you must seal the air holes. Here’s why. The wet core was a potential problem because of possible delamination from rot or ice. But now that the core is open to air another problem can occur, mildew. Mildew requires air and moisture. If a headliner is installed and a deck leak traps moisture between the headliner and deck, mildew is sure to occur. Mildew is a sure way to delaminate any structure but you can avoid it if you cut off the air by filling the air holes. While you are doing that you may as well fill any voids in the core at the same time."

cruisers5357

• Feb 11, 2014

Woodonglass said: My research found this which might be of interest... " When can a core simply be dried out instead of injected? If the core is not rotted, it can be dried out. To determine if the core is rotted, get at the back side of the laminate and drill a grid of 1/8? holes in a 1? checkerboard arrangement. Of course you are not drilling through both sides of the laminate. Drill only through the inside. Do this over the entire area that has a moist core. To get a neat, consistent pattern of holes I apply sticky back cabinet shelf paper. It comes in a checker board design. Clean out the flutes of the drill every few holes. Unrotted balsa will have no smell or smell like resin and it will be fibrous when you roll it in your fingers. Rotted balsa will smell moldy and have more of a mushy or dusty feel. If you are really unsure, drill a ?" hole and pick some of the balsa fibers out with a tweezers. Rotted fibers will crumble or mush. Good balsa will be much harder to remove and it will be very fibrous. How can a core be dried? If you are lucky enough to live in a northern climate, where the temperature moves above and below freezing in the spring and the fall, nature will dry the laminate after you?ve drilled the hole grid described above. Here, ice crystals form as the temperature drops and the moisture is driven out of the wood. Ever look at a loaf of freezer burnt bread with ice crystals collected in the plastic bag? This occurs when the temperature inside the freezer fluctuates above and below freezing. What you want is a freezer burnt core in your boat. If you are not in a northern climate, or worse you are in a high humidity climate, I cannot help you. Text books talk about injecting alcohol, using tents and halogen lights but I have not used these methods. When can a core be fixed with polyurethane injection versus traditional reconstruction? If the core is rotted, you need to fix it or the lack of core support will lead to much bigger problems. The question is when can you use simple injection versus tearing out the rotted area and replacing it? If the upper and lower fiberglass layers are structurally sound, the core can be repaired with injection. If the fiberglass does not show stress cracks or obvious hydrolysis (blisters or milky looking fiberglass), it will be fine. Large areas with stress cracks may be repaired with injection but I have not done that so I cannot predict the success. However, I can tell you this. I did do what was to be a temporary repair to a 30 foot Pearson Flyer that had a 6 inch crack in the hull. The outer hull had been punctured from a bad cradle pad. That was 10 years ago. When we injected the polyurethane from inside the hull, the polyurethane oozed out of the hull crack on the outside and then set up. The intent was to do a permanent repair after the racing season ended. A final repair was never done because the area around the temporary repair is stronger than the surrounding original hull. High pressure polyurethane injection Some jobs need high pressure injection and a very thin polyurethane sealant. Basically these are places where you cannot remove the core. Here, a grid of 1/8? holes needs to be drilled in the back side of the laminate. Or, you may be filling the hollow space within a rudder. The good news is that Vulkem 45, a thin polyurethane sealant, is available from Home Depot at a fraction of the cost of tradition thick, marine polyurethane such as 5200. Vulkem 45 comes in quart cartridges and it is thin enough to go through a pin hole. You can fill a handheld grease gun directly from the cartridge of Vulkem 45. Vulkem 45 is good for injection made under foot such as injection into a hull from the inside. Vulkem 45 can also work for large vertical injection such as a rudder. But for over head jobs use Vulkem 640. It is sold in gallon pails at a professional construction material dealer. Call Vulkem for a dealer location. Where as 45 is self leveling, 640 is the opposite. It will hang overhead yet it is quite thin. Buy a cheap grease gun from an automotive store. For the grease gun buy a POINT fitting at an automotive parts store such as NAPA and replace the normal grease fitting. Pump caulk into each of the 1/8? holes in your grid until caulk is oozing out of the hole(s) ahead. You may need to plug the hole(s) you?ve already done with golf tees. Buy a few bags of tees. Use a grease gun filled with Vulkem 640 or 45 and inject it into the core. Each 1/8" hole will take about 1.5 pumps from a handheld grease gun before you meet resistance. If you do not meet resistance, just keep pumping until sealant is coming out of at least one adjacent hole. You will hit some voids in a core that take a couple dozen pumps. These are spots where there was no core originally. This is typical on corners. Or the core may be rotted and you are compressing the rotted core material with the sealant. Once the sandwich has been dried and injected, water cannot reenter because the sandwich is solid. As a bonus, once the sandwich cures, it will feel much more solid. Note, it may take several months to fully cure. Low pressure polyurethane injection If you have removed the core, there is no need for high pressure or a thin polyurethane sealant. For example, if you have removed a 1 ft diameter circle of core material around a through fitting, the void will be easy to fill. Use 5200 or Vulkem 921 above the water line. Note, 921 is only available at a commercial construction material distributor. Removing a core around a through fitting is tedious but can be done. You will be able to remove the core for about 6? around a through fitting. To do this, you can make a routing tool from a flexible screwdriver extension attachment made by Vermont. Use a cutting wheel on a Dremmel to cut teeth in the end of the Vermont screwdriver attachment that normally holds the screwdriver bit. Then put the flexible screwdriver attachment into an electric drill and route out the core sliver by sliver. For a through hole fitting, after the core is removed, drill three holes at the edge of the removed core in a triangular pattern. Then wrap the through hull/deck fitting in enough cellophane so that it is hard to press it into the hole. Force it into the hole and inject caulk into the first of the three holes until it oozes out of the next hole, plug the hole and move on until all three holes are under pressure. Note, it takes weeks to months for the polyurethane to fully cure. Polyurethane cures in the presence of moisture so it will eventually cure. A partial cure is good enough to screw things back together. Wait a few weeks before doing that. After the core is dried can the air holes drilled under the deck be left open? If she is a racing boat without a headliner the air holes can be left unsealed. But if a headliner is installed you must seal the air holes. Here?s why. The wet core was a potential problem because of possible delamination from rot or ice. But now that the core is open to air another problem can occur, mildew. Mildew requires air and moisture. If a headliner is installed and a deck leak traps moisture between the headliner and deck, mildew is sure to occur. Mildew is a sure way to delaminate any structure but you can avoid it if you cut off the air by filling the air holes. While you are doing that you may as well fill any voids in the core at the same time." Click to expand...

Re: Injection repair of wet balsa core There is a company with a (portable) patent-pending process that injects extremely dry (<2% RH) heated air into 1/4" to 1/2" holes to dry out wet balsa and wet stringers. You can google the company it is called Dryboat  

• Forums New posts Unanswered threads Register Top Posts Email
• What's new New posts New Posts (legacy) Latest activity New media
• Media New media New comments
• Boat Info Downloads Weekly Quiz Topic FAQ 10000boatnames.com
• Classifieds Sell Your Boat Used Gear for Sale
• Parts General Marine Parts Hunter Beneteau Catalina MacGregor Oday
• Help Terms of Use Monday Mail Subscribe Monday Mail Unsubscribe

Plastic Hunter Crack Repair

• Thread starter H216sailor
• Start date Jun 26, 2018
• Tags crack hunter 216 repair
• Hunter Owner Forums
• Day Sailers

By now everyone is aware that the thermoplastic JY15, Hunter 146, 170, & 216 are all prone to cracking. A few weeks ago I purchased a 2004 Hunter 216 that had a small 6” crack at the bottom of the companionway and a large (aprox. 3’ long) crack from the mast step to the port side rail on the cabin top. This crack on the cabin top seems to be a common place for the 216 to crack as every one I looked at had this crack. I bought the boat for next to nothing and was determined to repair the boat. My first stop was this forum and now I’d like to share my experience in how I went about repairing the cracks on my 216. I have learned from the forum and from seeing repairs in person on 216’s and JY15’s that the regular fiberglass boat repair method of epoxy & fiberglass is NOT the way to go as the thermodynamics of epoxy is different from the thermodynamics of the plastic hull meaning the epoxy and the plastic hull will expand and contract at different rates and at some point, the repair will crack again. After reading many posts, I was ready to choose between the tried-and-true method of Plexus and a newer product called West System G-Flex. Before pulling the trigger, I wanted to make sure I wasn’t overlooking any repair option. I took a step back, left the “boat” part behind and thought “how do I repair plastic” and that’s when I came across what auto shops, ATV, and motorcycle guys have known all along – plastic welding. These boats are made from BASF Plastics product called Luran S which is a thermoplastic Acrylonitrile-styrene-acrylate or ASA. Many people refer to the plastic as ABS which is incorrect. They are both styrene based, but ASA is more resistant to temperature changes than ABS. I found a company that specialized in plastic repair products called www.polyvance.com and reached out to them about my repair. They were very knowledgeable, helpful, and friendly and set me up with a Mini-welder model 7 along with some ASA welding rod. I think I spent $200 for both. To complete the repair, I dremmeled out the crack, then used the welder to heat up the edges of the crack. The ASA welding rod is then inserted into the welder and comes out like a hot glue gun. I made sure the crack walls were still tacky to ensure a good bond with the ASA rod with the base material. I then used the welder like an iron to smooth out the repair and further ensure the repair was well bonded to the base material. You can sand it as soon as it cools, but I came back the next day and hit it with 100, then 220 grit sand paper. It can use some body filler, a good sanding, and some paint, but right now I am thrilled with how the repair came out! I’ll keep you updated on the repairs hold up long term. I have attached some pictures of the small companionway crack I repaired. The repairs are super strong, I can push on it, bang on it and it feels like any other spot on the boat!  

Attachments

@H216sailor , nice research and writeup. I've always wondered why the APC breaks where it does. Is the boat under some stress there? This is important because APC is in fact a 3-D LAMINATED structure (Luran-foam-fiberglass), and like all laminated structures gains strength from the layers being mechanically attached to each other. Any ask any ocean racer their biggest fear, and its the boats core delaminating from the carbon skins. Gluing the Luran crack closed does nothing to address the (weakened) laminated structure. Maybe its no wonder they break again?  

Correct, the boat is constructed with an outer Plastic skin, an inner fiberglass skin, and then both are joined together with expanding foam core in between the two. On these boats, the foam core is quite thick (over an inch in most places). In “traditional” cored boats, the worry is water intrusion rotting away the inner core leading to delamination and eventual hull failure. On my boat there was no stress on the repair as the boat has been sitting on the trailer since being repaired. No loads applied to the repaired area. Many of the cracks on these boats (146,170,212,216,JY15) are in areas with no loads. The general consensus is it is simply the thermo expansion and contraction of the plastic outer skin. In many cases including mine, there is no damage to the inner foam or inner fiberglass lining so there is no repair needed in these areas. The simple truth is these boats crack. The thermoplastic outer skin wasn’t such a good idea which is why Hunter went back to a conventional fiberglass hull. Unlike conventional boats, the cracking usually isn’t detrimental to the integrity of the hull. These boats can be repaired easily and continue to be enjoyed for years to come. These boats were never intended for any kind of offshore work whatsoever, but rather a few hour sail in protected waters. Even when my boat is repaired, I am aware that it will crack again due to thermo expansion and contraction, but I’d like to find a repair that works for me that I’m looking to last at least a year or two.  

I did not try this method. I have wire mesh but having already done a first pass at the repair, I’m not sure it will be the best method. There are many different types of plastic. Canoes and kayaks are typically made out of polyethylene which melts at 120c where a Hunter’s Luran S ASA plastic melts at 105c. Having repaired poly in the past, it melts much nicer than ASA and stays molten for a longer period of time making it much nicer and easier to work on. it can also withstand a lot of heat without burning. I am able to adjust the heat on my plastic welder, but ASA plastic is very fussy. It doesn’t like to melt but when it does, it’s quick to burn. You cannot melt the wire mesh into ASA like in those videos on poly kayaks. As for the milk jug video, the clear high density polyethylene has a hard time sticking to anything so I’m not sure how long a repair like that would hold up. I appreciate the help though. Because the plastics are soo different, I mostly try to stick to ASA or ABS repair videos for insight. I might try the PlastiFix, which is powered ABS plastic & solvent. It works the same way as the plastic welder only it’s a chemical reaction instead of head being applied. I’ll do a test with the plexus and PlastiFix on a small area of the repair. Good news is they are both $25  

Is there a reason why you are not using the tried and true Plexus adhesive? I recently purchased a 2005, 216, and there are a number of these crack I want to repair, but unable to find a Plexus distributer in Canada.  

KeukaSailer

A few different companies make it, Plexus, is really just methyl acrylate. I've had really good luck with "Locktite" branded methyl acrylate..Home depot sells it...near the epoxy.  

Thanks very much, I'll check it out. Happy sailing. Went to Home Depot, Lowes and Canadian Tire, no luck finding anything with "methyl acrylate", they did have LePage Marine Epoxy and J.B. Weld Marine Epoxy neither of which contains "methyl acrylate", going to call Hunter next business day for guidance.  

H216sailor said: Correct, the boat is constructed with an outer Plastic skin, an inner fiberglass skin, and then both are joined together with expanding foam core in between the two. On these boats, the foam core is quite thick (over an inch in most places). In “traditional” cored boats, the worry is water intrusion rotting away the inner core leading to delamination and eventual hull failure. On my boat there was no stress on the repair as the boat has been sitting on the trailer since being repaired. No loads applied to the repaired area. Many of the cracks on these boats (146,170,212,216,JY15) are in areas with no loads. The general consensus is it is simply the thermo expansion and contraction of the plastic outer skin. In many cases including mine, there is no damage to the inner foam or inner fiberglass lining so there is no repair needed in these areas. The simple truth is these boats crack. The thermoplastic outer skin wasn’t such a good idea which is why Hunter went back to a conventional fiberglass hull. Unlike conventional boats, the cracking usually isn’t detrimental to the integrity of the hull. These boats can be repaired easily and continue to be enjoyed for years to come. These boats were never intended for any kind of offshore work whatsoever, but rather a few hour sail in protected waters. Even when my boat is repaired, I am aware that it will crack again due to thermo expansion and contraction, but I’d like to find a repair that works for me that I’m looking to last at least a year or two. Click to expand

OwenPeter - no reason, I just figured if the base material can be melted and reformed, why not do that. Instead of using adhesive to repair ASA plastic, why not use ASA plastic? with that being said, my plexus is due to arrive tomorrow and I'll be finishing my repair with that plus fiberglass. I went back and re-welded the area with the hot welder paying close attention to really melt the base material before applying new ASA and it came out beautifully. I think I will still grind down the weld plus a little extra on wither side and finish with the plexus. Pictures to follow. I have used the Devcon plastic welder from Walmart on many different applications with great success. Before I started my repair on the boat I was able to find three of them unopened laying around the house. I decided to use the Devcon and the Mini-welder on scrap pieces of plastic. I found the Devcon to be very strong, but very rigid and not flexible. After putting a little weight on the scrap plastic Devcon weld, it broke along the repair. The plastic weld with the mini-welder was extremely strong, and was able to bend the piece very hard back and forth and no damage came to the weld. it was less of a repair and more of a re-molding back together. I'm not saying the boat can flex like how I was treating the practice repairs I made, but these boats are more flexible than a fiberglass boat.  

My weld has hairline cracks again! going to dremmel out a 3rd time and use the tried-and-true Plexus method. ordered my Plexus from Chembar ( https://www.chembar.com/?s=plexus ) and shipped to me very quickly. I only bought two of them, I hope that's enough for a 3' long crack. Any recommendations on what fiberglass to use?  

H216sailor said: ... I have learned from the forum and from seeing repairs in person on 216’s and JY15’s that the regular fiberglass boat repair method of epoxy & fiberglass is NOT the way to go as the thermodynamics of epoxy is different from the thermodynamics of the plastic hull meaning the epoxy and the plastic hull will expand and contract at different rates and at some point, the repair will crack again. ... Click to expand

H216sailor said: My weld has hairline cracks again! going to dremmel out a 3rd time and use the tried-and-true Plexus method. ordered my Plexus from Chembar ( https://www.chembar.com/?s=plexus ) and shipped to me very quickly. I only bought two of them, I hope that's enough for a 3' long crack. Any recommendations on what fiberglass to use? Click to expand

Hi JimInPB, thanks for the insight on your repair. Here is a link showing the thermal expansion of thermoplastics and fiberglass. I think you'll have less of a problem down in Florida than I'll have up here in CT over the winter. I agree with you that plastic welding just can't seem to get the same strength as the original. my Plexus has arrived and I'll grind out and repair as soon as I find some time to do it. I think I was set on the plastic welding at first because I was on a quest for a permanent repair. I thought if I used the plastic the boat is made out of for the repair, there would be no thermal expansion differences and the repair would last longer. I realize now I am not smarter than everyone and will use the tried-and-true Plexus. The plastic is remarkably easy to work on so even if the repair only lasts 1-3 years, its not really a big problem. I've been enjoying the boat so far. I've never been a huge fan of swing keels, but a few rubber door stops and not taking a powerboat wake directly on the bow makes for a much more pleasurable ride. I've been trailer sailing the boat as I'm less than a mile from the ramp. The boat is easier than a powerboat to launch and retrieve! She floats like a leaf on the water, literally almost no draft with the board up and rudder out. but the rigging/derigging can be a pain so I think I'll get a slip next year.  

H216sailor said: Hi JimInPB, thanks for the insight on your repair. Here is a link showing the thermal expansion of thermoplastics and fiberglass.... Click to expand

Dremmeled out the ASA weld and used Plexus MA300. I'm very happy with the result so far. when it dries, it shrinks a little so I will sand and reapply a second layer to get it flush with the cabin top. I guess I could use a regular automotive filler at this point, but I ordered way more plexus than I needed so I'll just use what I got.  

Crazy Dave Condon

H216 sailor. Thank you for an informative comments. As a former dealer repairing ACP plastic skin boats, I use to talk about repairs with Eddie Breeden who was Hunter's warranty manager and Dave Eck who owned JY boats who first built the ACP boats for Hunter before Hunter purchased JY. Further I experienced new boats that cracked like your 216 and others. Then I have seen many boats of this style manufacture located in all areas of the east coast that never cracked to include new ones that I sold. The leading cause as told was the manufacturer changing the formulation of the plastic sheets without authorization by JY or Hunter. When that happened, those boats being affected did correspond to the lots of material wherein the formulation had been changed without authorization. Both JY and Hunter had filed legal action. I am not an engineer but that seemed plausible. First I never used acetone, resin/hardner used in fiberglass and so on. I too became frustrated like you and tried other plastic welders. Finally what worked for me was going back to Plexus and the use of fiberglass mat. The very first thing I would do of course is drill 1/8 inch hole at the end of each crack so the crack would not migrate any further. Being retired for a while, I am not familiar with the newer West Brothers products. I would for the large cracks remove about a half inch or a little more of the plastic skin and then a little below the rest of the skin beveling the edge at a 45% angle or larger angle. Then I would remove some foam from beneath the edge of the plastic so I could insert some fiberglass impregnated with plexus under the plastic so it would lay flat with the bottom edges. The next layer of glass would be cut to fit the space to the appropriate beveled edge again impregnated with plexus. By doing this I created a locking way to repair the crack and then built up with larger layers of glass with plexus but stopped short before reaching the top. I allowed each layer to dry first. The last was of course plexus only and wet sanded to a smooth surface. The painted with the Krylon plastic paint but forgot the specific number. This worked for me. As for the smaller crackes I would Dremel out but the key would to be beveling the sides of the edge at 45 or higher degree angles and the use of fiberglass depended on the crack.  

Crazy Dave Condon said: ...The last was of course plexus only and wet sanded to a smooth surface. The painted with the Krylon plastic paint but forgot the specific number. ... Click to expand

• This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. By continuing to use this site, you are consenting to our use of cookies. Accept Learn more…