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Author Topic:   Gelcoat Repair - What did I do wrong?

STinSC posted 09-08-2009 09:45 AM ET (US)
A few months ago I installed a new chart plotter on my [1986 OUTRAGE 18] and repositioned the transducer on the transom. I ordered Spectrum's gel coat repair kit to fill in the screw holes where the old transducer was mounted. I drilled out the holes, inserted wooden dowels swabbed in 5200 to fill the void and then applied the Spectrum gelcoat and then sanded. It looked great.
Since then I find that the holes appear to be weeping a dark acidic residue. The holes are completely filled and flush with the side of the transom but there is definitely a residue that is appearing outside of the holes.
What did I do wrong? Did I not mix the hardener with the gelcoat paste properly? Any comments or suggestions are greatly appreciated.
ST
Blackduck posted 09-08-2009 11:06 AM ET (US)
The holes should have been filled with an epoxy or fiberglass resin, mixed with some filler. I don't like using dowels, and even if you insist on using them, they should fit loose, and be covered and glued with the fore mentioned adhesives, not 5200. The gelcoat layer is strictly for cosmetic purposes. You need to do these repairs over, re drill the holes, and get them clean and dry.
Buckda posted 09-08-2009 11:14 AM ET (US)
How deep did you drill the hole for the repair? I'm asking because you could have tapped a resevoir of uncured resin from within the hull that has found your repair as a conduit out.
Let's go back to the basics here though before we go forward.
Your transom is made from laminated sheets of wood built out to the thickness needed. A dowel is not an appropriate method of filling the hole for a lasting repair - the wood grain is different and the repair will eventually "pop" from the contrast in heating and cooling characteristics across the grain of these woods.
Recommend you re-drill the hole (make a jig as it will be difficult to remove just the dowel) and then fill the hole with ganged up "plugs" of wood glued together.
Feather the edges of this hole along the gelcoat, creating an area that is 2x the width of the actual hole.
Let the plug/epoxy cure fully before mixing up the gelcoat patch and then apply it carefully over the hole and feathered gelcoat. Sand smooth, polish and wax.
My guess is that you didn't use enough hardener, and uncured resin is now seeping out of the repair.
Gelcoat is not impermeable.
Dave
Tom W Clark posted 09-08-2009 11:37 AM ET (US)
I agree about not using dowels for filling holes.
The leakage that you are seeing is not uncured resin from the repair. Spectrum Gel Coat Patch Paste in not a liquid. Even if you did not catalyze it all it will not leak out as described.
What you are seeing is moisture from within the hull, probably absorbed by the plywood of the transom from an improperly sealed screw from the old transducer. This is very common, almost ubiquitous among Whalers.
When you made the repair, the caulk did not perfectly bond with the wet surface it was applied to and an avenue of leakage was left behind.
The gel coat patch paste will not necessarily make a perfect water tight bond by itself every time.
Using 5200 is not a bad idea as a base...if you can get it to seal the hole, but you might try using some polyurethane glue (Gorilla Glue is one brand) to glue in plugs of wood that you can then seal.
Polyurethane glue will cure in the presence of moisture, in fact it needs water to cure. But if there is water weeping out of the transom when the glue is setting up, you may still end up with a leak.
The best time to seal the hole is when it is cooler outside. I have noticed that in warmer weather, or direct sunshine, a weep hole will be more productive on a Whaler hull. When it cools down, the weeping will stop.
Try plugging the hole in the evening and letting the glue cure overnight.
When plugging hole with wood plugs, I just cover a plug with glue and insert it into the hole that I have also coated with glue. If he depth requires another plug, just add it, keep inserting plugs until you have filled the hole.
Be sure to overfill the hole. Once the glue is cured, use a Forstner drill bit to drill back down to the depth of the transom;s plywood core. You now have a clean hole you can fill with epoxy or polyester resin. Gel coat over that, though in reality, if the hole is sealed properly, You *can* use Spectrum Gel Coat Patch Paste to fill the hole in one application.
Blackduck posted 09-08-2009 12:29 PM ET (US)
I do normally first inject the hole with 5200, letting it fill in all the missing foam, ect, my back up leak stopper, so to speak. I then, with a Dremel tool, remove all the extra 5200 down to the end of the laminate, or wood, before filling with epoxy, the main repair element.
jimh posted 09-08-2009 11:58 PM ET (US)
I have filled many holes on the transom of my three Boston Whaler boats because I bought them all second-hand, and they had old SONAR transducers I wanted to remove or relocate. It has been my good fortune that the transoms were all very dry, and I had no water at all to deal with.
I filled the holes with some very soft wood plugs made from soft dowel, the sort of stuff you get at a hardware store. I used WEST System epoxy. I left room in the hole for a top coat of epoxy that was tinted and had some filler. Because the transom is vertical, it is hard to keep the resin in the holes. I usually push in as much as I can, then put a piece of masking tap over it. When the resin cures, it usually fills most of the hole. A second pass may be needed.
I also carefully tape off around the holes so there is no extra resin on the original gel coat surface. This is very important with epoxy because cured epoxy is harder than 20-year-old gel coat resin. When you sand the repair to fair it into the hull, you can easily sand away more of the surrounding gel coat than the epoxy of the repair.
The color of the epoxy ages and yellows, but I only see this when the boat is on the trailer. The rest of the time the holes are underwater. The color match is not perfect, but it is not horribly bad, either. After a year or two the epoxy seems to stop yellowing and settles into a stable color.
I am not much of a fan of 3M5200 as a filler or structural material. It is a great adhesive and sealant.

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Author	Topic: Gelcoat Repair - What did I do wrong?
STinSC	posted 09-08-2009 09:45 AM ET (US) A few months ago I installed a new chart plotter on my [1986 OUTRAGE 18] and repositioned the transducer on the transom. I ordered Spectrum's gel coat repair kit to fill in the screw holes where the old transducer was mounted. I drilled out the holes, inserted wooden dowels swabbed in 5200 to fill the void and then applied the Spectrum gelcoat and then sanded. It looked great. Since then I find that the holes appear to be weeping a dark acidic residue. The holes are completely filled and flush with the side of the transom but there is definitely a residue that is appearing outside of the holes. What did I do wrong? Did I not mix the hardener with the gelcoat paste properly? Any comments or suggestions are greatly appreciated. ST
Blackduck	posted 09-08-2009 11:06 AM ET (US) The holes should have been filled with an epoxy or fiberglass resin, mixed with some filler. I don't like using dowels, and even if you insist on using them, they should fit loose, and be covered and glued with the fore mentioned adhesives, not 5200. The gelcoat layer is strictly for cosmetic purposes. You need to do these repairs over, re drill the holes, and get them clean and dry.
Buckda	posted 09-08-2009 11:14 AM ET (US) How deep did you drill the hole for the repair? I'm asking because you could have tapped a resevoir of uncured resin from within the hull that has found your repair as a conduit out. Let's go back to the basics here though before we go forward. Your transom is made from laminated sheets of wood built out to the thickness needed. A dowel is not an appropriate method of filling the hole for a lasting repair - the wood grain is different and the repair will eventually "pop" from the contrast in heating and cooling characteristics across the grain of these woods. Recommend you re-drill the hole (make a jig as it will be difficult to remove just the dowel) and then fill the hole with ganged up "plugs" of wood glued together. Feather the edges of this hole along the gelcoat, creating an area that is 2x the width of the actual hole. Let the plug/epoxy cure fully before mixing up the gelcoat patch and then apply it carefully over the hole and feathered gelcoat. Sand smooth, polish and wax. My guess is that you didn't use enough hardener, and uncured resin is now seeping out of the repair. Gelcoat is not impermeable. Dave
Tom W Clark	posted 09-08-2009 11:37 AM ET (US) I agree about not using dowels for filling holes. The leakage that you are seeing is not uncured resin from the repair. Spectrum Gel Coat Patch Paste in not a liquid. Even if you did not catalyze it all it will not leak out as described. What you are seeing is moisture from within the hull, probably absorbed by the plywood of the transom from an improperly sealed screw from the old transducer. This is very common, almost ubiquitous among Whalers. When you made the repair, the caulk did not perfectly bond with the wet surface it was applied to and an avenue of leakage was left behind. The gel coat patch paste will not necessarily make a perfect water tight bond by itself every time. Using 5200 is not a bad idea as a base...if you can get it to seal the hole, but you might try using some polyurethane glue (Gorilla Glue is one brand) to glue in plugs of wood that you can then seal. Polyurethane glue will cure in the presence of moisture, in fact it needs water to cure. But if there is water weeping out of the transom when the glue is setting up, you may still end up with a leak. The best time to seal the hole is when it is cooler outside. I have noticed that in warmer weather, or direct sunshine, a weep hole will be more productive on a Whaler hull. When it cools down, the weeping will stop. Try plugging the hole in the evening and letting the glue cure overnight. When plugging hole with wood plugs, I just cover a plug with glue and insert it into the hole that I have also coated with glue. If he depth requires another plug, just add it, keep inserting plugs until you have filled the hole. Be sure to overfill the hole. Once the glue is cured, use a Forstner drill bit to drill back down to the depth of the transom;s plywood core. You now have a clean hole you can fill with epoxy or polyester resin. Gel coat over that, though in reality, if the hole is sealed properly, You can use Spectrum Gel Coat Patch Paste to fill the hole in one application.
Blackduck	posted 09-08-2009 12:29 PM ET (US) I do normally first inject the hole with 5200, letting it fill in all the missing foam, ect, my back up leak stopper, so to speak. I then, with a Dremel tool, remove all the extra 5200 down to the end of the laminate, or wood, before filling with epoxy, the main repair element.
jimh	posted 09-08-2009 11:58 PM ET (US) I have filled many holes on the transom of my three Boston Whaler boats because I bought them all second-hand, and they had old SONAR transducers I wanted to remove or relocate. It has been my good fortune that the transoms were all very dry, and I had no water at all to deal with. I filled the holes with some very soft wood plugs made from soft dowel, the sort of stuff you get at a hardware store. I used WEST System epoxy. I left room in the hole for a top coat of epoxy that was tinted and had some filler. Because the transom is vertical, it is hard to keep the resin in the holes. I usually push in as much as I can, then put a piece of masking tap over it. When the resin cures, it usually fills most of the hole. A second pass may be needed. I also carefully tape off around the holes so there is no extra resin on the original gel coat surface. This is very important with epoxy because cured epoxy is harder than 20-year-old gel coat resin. When you sand the repair to fair it into the hull, you can easily sand away more of the surrounding gel coat than the epoxy of the repair. The color of the epoxy ages and yellows, but I only see this when the boat is on the trailer. The rest of the time the holes are underwater. The color match is not perfect, but it is not horribly bad, either. After a year or two the epoxy seems to stop yellowing and settles into a stable color. I am not much of a fan of 3M5200 as a filler or structural material. It is a great adhesive and sealant.