Drilled in the Wrong Spot

Uh oh, I was installing trim tabs on my Whaler tender and drilling from and awkward position I drilled 3 holes (7/32) in the wrong position. What should I fill the holes with? 4200, 5200 or something else?

a more permanent solution would be thickened epoxy.

Poker is right, especially if the hole is through to the foam. That's just short of 1/4", and there ought to be enough space to pack a tight roll of glass cloth in there, soaked with epoxy. Snip off the excess and dremel the bung flush.

hmason said:

Uh oh, I was installing trim tabs on my Whaler tender and drilling from and awkward position I drilled 3 holes (7/32) in the wrong position.

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We call those "practice holes".

Measure once, Drill twice. Thickened epoxy would sure take care of it.


1983 Present 42 Sundeck
Twin Lehman 135's

Do NOT use caulking. Eventually it will come free of the fiberglass and allow leakage into the core.

Use raw, unthickened epoxy to wet the core and the fiberglass. Then wet some cloth and then lather that cloth with thickened epoxy and roll it as tight as you can and stuff into the hole. There will be lots of squeeze out so be prepared.

Then once the cloth is in the hole tape over it and using a hypodermic needle filled with lightly thickened epoxy poke a hole and squeeze as much of that thickened epoxy into the hole as it will take continuing to gently press the plunger as you withdraw the needle. Let it set up for a day or two and remove the tape. You can sand it smooth after or as suggested use a dremel carefully.

If the hole is quite small then you may not be able to use cloth. Then use the minifiber filler to thicken the epoxy and use the hypo to inject and fill the hole.,,For small hole wetting a few pipe cleaners work very well.
But wet the hole with unthickened epoxy first regardless.

The use gelcoat to colour and disguise the hole. This will be a permanent, reliable repair.

I know , and I've said it myself, that wisdom says you cannot apply gelcoat over epoxy but according to a recent article from Gougeon Bros., West System Epoxy, that is not so.
Carefull prep is needed but apparently it can be successfully done.

Free Gougeon Bros mag. Number 42, Spring 2016.

Applying Polyester Gelcoat over Epoxy | Epoxyworks

Just shove some Marine Tex in it and forget it.

Assume under the waterline?

Epoxy.

A proper repair of a hole in fiberglass involves grinding the surface to a taper and applying varying sizes of fiberglass cloth and resin to build up the surface, then sanding and applying gelcoat.


The solution I don't believe anyone suggested is to put some sealant on the proper sized screws and drive them in. You were going to do that anyway, just in another place.

I vote for marine tex use a toothpick to smear the stuff all around the interior of the hole for solid contact. Make sure to stuff the hole full. If it is a blind hole you have to be certain to get out any trapped air that would prevent proper filling.

Forkliftt said:

Measure once, Drill twice. Thickened epoxy would sure take care of it.


1983 Present 42 Sundeck
Twin Lehman 135's

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I think it's measure twice, drill once. ?

Pgitug said:

I think it's measure twice, drill once. ?

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I think his comment was on what was done, not what should have been done!

1 if the location is suitable, put a bolt in with epoxy on the threads. or
2 countersink the holes, use thickened gelcoat to fill, then un-thickened to dress the surface. Sand with 400 or + and polish and it disappears.

wow....think about this....if you drilled where the skin is thin...all these suggestions like tapering the hole and using bolts, etc.....are pretty iffy unless you have experience doing this kind of work.


small boston whalers the I have worked on unless a reinforced area...the glass isn't very thick.


without actually seeing the holes and what is immediately behind them....I would find a way to inject a small blob of thickened epoxy behind the hole and let harden. Then I would see if I could get a layer of 6 oz cloth or two layers (lighter cloth if necessary) over the hole...only tapering if there's enough meat there...and if below the waterline and bottom painted...ignore the tapers.


Bottom line..the thickness of the skin where the holes are determines the best repair....unless a pro who might try another option or two.

If the skin is that thin, how would it hold trim tabs in the first place?

Just asking or pointing out...about the skin thickness...

My first sentence does use the word "IF".


That's why I have never liked Boston Whalers after the first batch the USCG tossed....

Not sure why they bought into more....not that BWs don't have good attributes...just their skins were never my choice but not sure which models might have had properly reinforced areas for options or after market items.

HopCar said:

Just shove some Marine Tex in it and forget it.

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menzies said:

Assume under the waterline?

Epoxy.

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Isnt marinetex epoxy?

HopCar said:

Just shove some Marine Tex in it and forget it.

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This, or JB Waterweld. NOT caulk or sealant.

Well thanks for all the advice. I am going to fill the hole with MarineTex. Then, the mounting plate for the trim tab will go over that repair. I will bed the mounting plate with 4200 and screw it down tight. Should hold pretty well I think.

MarineTex is fine. If it was me I'd mix up some West System with 205 fast hardener and thicken with a smidgen of 404 high density filler to bring it to between mayonnaise and peanut butter consistency. Then I would apply with a west system epoxy syringe: WEST SYSTEM #807 Dispensing Syringes, 12-pack | West Marine Maybe cover with some blue painters tape until cured, then remove the tape trim the "circle" of epoxy stuck to the tape.

hmason said:

Well thanks for all the advice. I am going to fill the hole with MarineTex. Then, the mounting plate for the trim tab will go over that repair. I will bed the mounting plate with 4200 and screw it down tight. Should hold pretty well I think.

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That'll work!

Forkliftt said:

Measure once, Drill twice.

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"I have cut this damn thing twice and it is STILL too short."

:lol::lol::lol::lol::lol:

I build boats. This is how I do it. Measure twice, cut once, throw it out, repeat. It takes me a very long time to finish a boat.

HopCar said:

I build boats. This is how I do it. Measure twice, cut once, throw it out, repeat. It takes me a very long time to finish a boat.

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AND it's 10 feet shorter than planned

Well not quite that bad but my 14 foot skiff measures 13 feet.

I'm so happy I'm not alone. I love having company.

Reinforcement for added components and the forces applied by them is of great importance on cored areas of a hull. Just food for thought.

Marinetex obviously will work. Out here in downunderland, I would use this stuff...it's moorvelous...and I have been know to drill a 'hole I find I no longer need...'

Selleys Knead It Multipurpose - Epoxy Putty | Selleys Australia

I've used that type of product before with great success. Thanks for the reminder.

Pete, I keep a tube of similar stuff on my boat. It has come in handy a couple of times. It would be fine for the OP's problem and would be less messy than Marine Tex. It does have a limited shelf life so I replace mine every couple of years, if I think of it.