Filling holes

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12Parker2320

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Replacing the trumpet horns on top of my 2320 cab. I went with the all SS Ongaros which I plan to angle them down on installation. This is my first fiberglass boat and I am curious how you guys are filling holes? My main concern is rain water intrusion. I have always filled the holes by fitting the right size screw and filling with 5200 or another strong sealant
 

shawnee83

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Polyester resin mixed with cabosil. Do a YouTube search on making peanut butter and you can see how to make the mix. Top off with gel coat. Actually, holes that small just use the resin and hardener and syringe.
 

12Parker2320

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Polyester resin mixed with cabosil. Do a YouTube search on making peanut butter and you can see how to make the mix. Top off with gel coat. Actually, holes that small just use the resin and hardener and syringe.
Thanks
 

pelagic2530

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Polyester resin mixed with cabosil. Do a YouTube search on making peanut butter and you can see how to make the mix. Top off with gel coat. Actually, holes that small just use the resin and hardener and syringe.
Either polyester or epoxy resin will work for this. Epoxy is a bit pricier, but if you're new to working with fiberglass and resins there's a lot of good material on how to work with it. I would recommend West System, as their instructions and material guides are well-written and easy to follow. Check out their website. For a repair this size, they offer a small "repair kit" with small packs of resin and hardener, so you don't need to buy a whole can of both, pump kits, etc. The cabosil filler is optional for a hole this size, but it does help give the epoxy a little thicker consistency which can help. You'll likely have to buy a whole can of it, but it's relatively cheap and it doesn't go bad, so if you have other repair, installation, or sealing work to do in the future you'll have a supply. If you're planning on doing any work or modifications to a cored boat, having fiberglass materials on hand is never a bad thing. I'm not aware of a source to buy small quantities of polyester resin materials, and epoxy tends to be more generally useful anyway.

When you go to fill the holes, I would recommend drilling them out to a larger size to ensure that you've cleaned out all the old silicone or caulking material (which is likely what they were sealed with originally). Drill slightly larger sizes until you get clean wood core material on the inside of the hole. This is a good time to check and make sure the core is dry and not rotten. Tape off the bottom of the hole; I use Gorilla tape as it creates a good strong seal and pulls off cleanly. If you use masking tape and the epoxy leaks by, it can create a big mess that's difficult to clean up. Start by mixing the epoxy unthickened, and use the thin epoxy to "wet out" the core material by brushing it in with a small brush (a Q-tip works well also). The thinned epoxy will likely soak up into the core, which is good. Then, thicken the epoxy mix with a bit of cabosil filler if you choose to use it. Add it a bit at a time, it will seem very thick when you first add it but will thin out as you mix it. Then, fill the hole with the thickened mixture. The best way is to pump it in with a plastic syringe, but if you're really careful you can drip/pour it in slowly. Keep an eye on it as it cures; more than likely the epoxy will continue to be absorbed by the core material and the level in the hole will drop. That's where the syringe is handy to top it off a bit. NOTE: if the level drops significantly and/or quickly, check the tape on the underside of the hole! Chances are it's leaking by, and it's way easier to clean up spilled epoxy before it cures. Ask me how I know...

After the epoxy is cured, you will need to cover the plugged hole with something in order to prevent UV rays from degrading the cured resin. You can use gelcoat for this if you're looking for a factory perfect finish. However, for a repair this small, you could also get away with marine paint, or even a dab of 3M 4200 or similar sealer over it if you're not concerned about the aesthetics. That will ensure your holes are patched, water intrusion is stopped, and the plug won't degrade.

Now... how are you planning on mounting the hardware for the new horns?? Lots of material on here regarding how to create an epoxy plug for the mounting hardware, so that water won't be able to leak past the sealant (which will eventually fail) and into the roof core. The process is similar to the plug described above; the differences are: 1) drill the hole for the new hardware out to about 5/16", or a slightly larger diameter than the fasteners you're going to use; 2) don't drill all the way through the roof, leave the bottom fiberglass skin intact, so you don't have to worry about sealing the bottom of the hole; and 3) once the hole is filled and cured, re-drill the epoxy plug with the size hole needed for your fasteners, and install the fasteners with sealant for good measure into the epoxy plug. That way, your core remains sealed and water intrusion won't happen. Obviously, make sure the hole you drill for the epoxy plug is deeper than the depth of the hole needed for your fasteners, so you don't poke through the plug with the screws, and when drilling the final screw hole in the epoxy plug be sure not to break through the bottom. I find marking drill bits to the correct depth with a tag of tape works well. The list of materials for both projects is the same; in fact, I'd recommend doing them at the same time with the same batch of epoxy to minimize wasted resin.

Material list:
-West System epoxy repair kit (or, if you anticipate doing a lot of these types of projects, buy a can of resin and hardener and the associated mini-pumps)
-West System cabosil filler material- optional
-Plastic syringe (the West System ones work, but are very expensive for what they are. You can sometimes find disposable irrigation syringes at drugstores)
-Mini brush and/or Q-tips
-Tape for the bottom of the hole
-Tape for the area around the hole (makes cleanup easier)
-Mixing stick for epoxy- an actual "stick" works fine for this
-Paper towels for cleanup (you'll get messy).
-3M 4200 or UV4000 sealer to cover old hole plugs and to seal new hardware.

All of this is available at West Marine if you're willing to pay for the convenience and to see it before you buy, or online if you'd prefer to order it and wait to maybe save a bit of money.
 

Legal Bill

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You might find this product will simplify the process for you.
 

warthog5

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It was mentioned about drilling the holes a little larger......Yes....and along with that. I chamfer / Countersink the hole....It just gives more surface area to cling to. You will want to put duct tape on the inside. You don't want a mess inside to "Try" and clean up. A lot of times it takes 2 applications, as the material will shrink back. For a final wipe I use a single edge razor blade on small holes like that.
 

12Parker2320

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Either polyester or epoxy resin will work for this. Epoxy is a bit pricier, but if you're new to working with fiberglass and resins there's a lot of good material on how to work with it. I would recommend West System, as their instructions and material guides are well-written and easy to follow. Check out their website. For a repair this size, they offer a small "repair kit" with small packs of resin and hardener, so you don't need to buy a whole can of both, pump kits, etc. The cabosil filler is optional for a hole this size, but it does help give the epoxy a little thicker consistency which can help. You'll likely have to buy a whole can of it, but it's relatively cheap and it doesn't go bad, so if you have other repair, installation, or sealing work to do in the future you'll have a supply. If you're planning on doing any work or modifications to a cored boat, having fiberglass materials on hand is never a bad thing. I'm not aware of a source to buy small quantities of polyester resin materials, and epoxy tends to be more generally useful anyway.

When you go to fill the holes, I would recommend drilling them out to a larger size to ensure that you've cleaned out all the old silicone or caulking material (which is likely what they were sealed with originally). Drill slightly larger sizes until you get clean wood core material on the inside of the hole. This is a good time to check and make sure the core is dry and not rotten. Tape off the bottom of the hole; I use Gorilla tape as it creates a good strong seal and pulls off cleanly. If you use masking tape and the epoxy leaks by, it can create a big mess that's difficult to clean up. Start by mixing the epoxy unthickened, and use the thin epoxy to "wet out" the core material by brushing it in with a small brush (a Q-tip works well also). The thinned epoxy will likely soak up into the core, which is good. Then, thicken the epoxy mix with a bit of cabosil filler if you choose to use it. Add it a bit at a time, it will seem very thick when you first add it but will thin out as you mix it. Then, fill the hole with the thickened mixture. The best way is to pump it in with a plastic syringe, but if you're really careful you can drip/pour it in slowly. Keep an eye on it as it cures; more than likely the epoxy will continue to be absorbed by the core material and the level in the hole will drop. That's where the syringe is handy to top it off a bit. NOTE: if the level drops significantly and/or quickly, check the tape on the underside of the hole! Chances are it's leaking by, and it's way easier to clean up spilled epoxy before it cures. Ask me how I know...

After the epoxy is cured, you will need to cover the plugged hole with something in order to prevent UV rays from degrading the cured resin. You can use gelcoat for this if you're looking for a factory perfect finish. However, for a repair this small, you could also get away with marine paint, or even a dab of 3M 4200 or similar sealer over it if you're not concerned about the aesthetics. That will ensure your holes are patched, water intrusion is stopped, and the plug won't degrade.

Now... how are you planning on mounting the hardware for the new horns?? Lots of material on here regarding how to create an epoxy plug for the mounting hardware, so that water won't be able to leak past the sealant (which will eventually fail) and into the roof core. The process is similar to the plug described above; the differences are: 1) drill the hole for the new hardware out to about 5/16", or a slightly larger diameter than the fasteners you're going to use; 2) don't drill all the way through the roof, leave the bottom fiberglass skin intact, so you don't have to worry about sealing the bottom of the hole; and 3) once the hole is filled and cured, re-drill the epoxy plug with the size hole needed for your fasteners, and install the fasteners with sealant for good measure into the epoxy plug. That way, your core remains sealed and water intrusion won't happen. Obviously, make sure the hole you drill for the epoxy plug is deeper than the depth of the hole needed for your fasteners, so you don't poke through the plug with the screws, and when drilling the final screw hole in the epoxy plug be sure not to break through the bottom. I find marking drill bits to the correct depth with a tag of tape works well. The list of materials for both projects is the same; in fact, I'd recommend doing them at the same time with the same batch of epoxy to minimize wasted resin.

Material list:
-West System epoxy repair kit (or, if you anticipate doing a lot of these types of projects, buy a can of resin and hardener and the associated mini-pumps)
-West System cabosil filler material- optional
-Plastic syringe (the West System ones work, but are very expensive for what they are. You can sometimes find disposable irrigation syringes at drugstores)
-Mini brush and/or Q-tips
-Tape for the bottom of the hole
-Tape for the area around the hole (makes cleanup easier)
-Mixing stick for epoxy- an actual "stick" works fine for this
-Paper towels for cleanup (you'll get messy).
-3M 4200 or UV4000 sealer to cover old hole plugs and to seal new hardware.

All of this is available at West Marine if you're willing to pay for the convenience and to see it before you buy, or online if you'd prefer to order it and wait to maybe save a bit of money.
Thanks for the very detailed response and step by step process. As far as the new hardware I sealed with 4200 and added bolt head caps and sealed them as well. It’s probably not the best but my boat is covered well when stored
 

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