What should I use to fill holes below waterline

[Unclematt]

After removing the trim tabs I am left with about 20 - 1/4 holes through the hull. I am thinking of using Total Boat Thickso to fill them. I then will need to do some filling, fairing and a final finish before paint. What would you guys use. FYI I took them off because my boat is a 7 to 10 mph trawler and they were not working and full of holes.

 

[Comodave]

Is that the epoxy that comes in a caulk gun, if so it should work. Before filling the holes I take a countersink and countersink the holes to clean up the gel coat where the screws have chewed the gel coat up. It allows the epoxy to get into the holes easier and maybe farther in, maybe. But it is easy to do and doesn’t hurt.

 

[O C Diver]

Assuming your boat is fiberglass and not cored, I would drill the holes oversize to make sure no caulking remains, chamfer the outside of the holes, and fill them with West System epoxy with bonding filler. I would make the West System into a putty slightly thicker than peanut butter. If you slightly overfill the holes, you should be able to sand them flush with the transom.

Ted

 

[Snapdragon III]

I agree with the above, but would wipe them down with acetone to be slightly under filled. Then put a second thin layer on top with a lighter fairing filler. The bonding filler is super hard to sand, and I always mess up the area around it when I have tried.

 

[SoWhat]

I used West Six10 epoxy. Drilled all holes a little oversize. Hard to sand so used a final coating of 105 with microfiller.

 

[bayview]

Pushing filler into holes does not work because air gets trapped under the filler. A little bit at a time with toothpick or such to spread it around the sides for good contact and force air to bubble out.

 

[Comodave]

That’s why you oversize the holes a bit.

 

[Unclematt]

The holes go thorough the hull and it is about 3/4 thick fiberglass. Should I clean and tape the inside of the hole at least where I can reach or just fill it and let some ooze through?

 

[Comodave]

If you have a helper to do the inside while you shoot it in from the outside I would let it come out the inside and fill the hole then scrape off the excess on the inside before it cures. Then tape the inside so it won’t run out while curing. That way you can be sure the hole is completely filled. But it may be thick enough so it won’t run out.

 

[O C Diver]

The holes go thorough the hull and it is about 3/4 thick fiberglass. Should I clean and tape the inside of the hole at least where I can reach or just fill it and let some ooze through?

I would let it ooze through and squeegee off the excess when you're happy with the outside.

Ted

 

[SoWhat]

I put painters tape on the inside. Epoxy pushed it out a bit so I know there was solid penetration. Didn't bother to sand it down. Lazarette is not a dining area.

 

[Cigatoo]

Drill out holes to 3/8. Chamfer the holes with a counter sink. Get some 3/8 teak bung plugs. Clean everything well with acetone Wet the inside of hole and bung with epoxy. Drive the bung into the hole so it is about 3/8 inch below the surface. Fill remainder of hole with epoxy thickened enough so it won’t sag. Peanut butter consistency.

 

[psneeld]

Why use teak or any kind of fill material on a 1/4 inch hole?

Especially a through hole that won't air pocket?

 

[C lectric]

I have filled holes although not below the water line. They were open ended.
I used epoxy. I overdrilled the holes to clean out residue and expose the raw , in this case wood.

I used pipe cleaners and small brushes to coat the hole interior walls with raw epoxy for small holes, 1/8 or less.

Larger holes I taped both ends and punctured a small hole at the tape tops for air escape. I used a syringe filled with raw epoxy and perforated the tape at the BOTTOM with the needle to fill from bottom up. Use a big needle. Fill the hole with raw epoxy untill it starts to come out of the air escape holes. Tape over the air and fill holes to stop oozing .

I let them sit for 5 minutes and then sucked it out and used the pipe cleaners to remove excess. The 5 minutes is to ensure all of the wall surfaces are coated and if there is ANY wood then the wood has soaked some of it up.
I would clean out excess so the thickened epoxy would not have a thick layer of the raw as not wanted, just enough to coat and be absorbed.

You can clean the syringe and needle with acetone or simply use a new one

I then mixed a thickened epoxy filler using microfibres but other good fillers may work better. Once the stuff is mixed I then filled the syringe again or used a new one if the raw stuff was getting a bit too thick. Getting the thickened epoxy in was a bit of a pain untill I started pouring it into the syringe. It was pourable but just so.

Then I used the same procedure with new tape and filled from the bottom slowly untill the thickened stuff started out at the top holes.
I then slapped another piece of tape over all the holes so it would not ooze out.
THe tape came off quite easily the next day as the adhesive prevented the epoxy from adhering.

Just get your tape pieces lined up ready to go. I would actually stick them to the hull nearby with a big enough tail that would stick leaving enough tape to adhere where I wanted it to cover the work.

This has taken longer to write than each hole took to fill.

 

[Comodave]

You might consider countersinking both the inside and outside of the holes. It will help lock the epoxy in having the slightly larger then the inside.

 

[Sailor of Fortune]

Don't overthink it, fill it,fair it refinsh it and move on...not rocket science

 

[DrissZougari]

Or you could just put back the screws with washers and some 5200. bottom paint will make them invisible

 

[Unclematt]

I ended up drilling to 3/8 and tapering the outside edge of the hole. I mixed up some West System and epoxied in 3/8 teak bungs set in as far as I could without pushing them through. I let it set up and filled the remainder with Thickso. Tonight I will sand it smooth, clean it and add a barrier coat. Thanks for the bung use ides it came out very nice.

 

[psneeld]

Or you could just put back the screws with washers and some 5200. bottom paint will make them invisible

Better if bronze...SS underwater not totally goobered up and covered with paint can deteriorate in years and become a slow leak. At least in both my experience and reading.


Always best to epoxy the holes up...unless done very poorly....seems to be the most problem free and pretty easy to do.


It follows my concept of ...reliability x effort x cost = good enough (risk managed) solution as not everything has to meet the "perfect" solution as often there is none.

 

[sbman]

I would dish out the hole/holes to layup glass on both sides if available. For small holes like that I would be OK with only dishing out a small amount and using some filler between the inside and outside layup and not dishing out huge like you would for a large hole. At least 1.5" around the hole though. After the cloth and filler was in place, some fairing compound to fair the surface followed by whatever coating system is in use for that area.

I would never fill a below the waterline hole without laying up some cloth to secure the repair. Ideally I'd want cloth on both sides of the hole.

I was onboard a friends boat when an unsecured (no cloth) repair failed, the filler came free and it was pumps vs the leak. Not fun. I would not epoxy wood in there either, it expands and contracts and cracks, fiberglass and epoxy does not so the relative movement between them can cause issues.

 

[bfloyd4445]

Well said.

 

[Bryant]

Boat holes

After removing the trim tabs I am left with about 20 - 1/4 holes through the hull. I am thinking of using Total Boat Thickso to fill them. I then will need to do some filling, fairing and a final finish before paint. What would you guys use. FYI I took them off because my boat is a 7 to 10 mph trawler and they were not working and full of holes.

Drill out, countersink holes and use “Marine Tex” and a squeegee. I’ve used that with success. It’s readily available, inexpensive, easy to use and dries harder than the surrounding area and is easy to sand. I keep some on my boat all the time.