Filling small underwater screw holes in grp hull

[Poignard]

Removal of two redundant B&G Log Impellor Deflectors has left me with 6 underwater screw holes to fill. Removal of the old helicoil inserts and enlarging the holes to expose fresh grp will leave blind holes of about 10mm diameter with depths of 20 to 35 mm.

These holes have been there for forty years and are obviously not weakening the hull. What is needed is a cosmetic means of filling them in. Something that will adhere well to the hull, e.g. epoxy, and be waterproof.

What is the best way to fill these holes, from the outside and working overhead so that the blind holes are completely filled [i.e. no voids]?

 

[Bergman]

They sound quite large holes to me

I would do this in stages.

First use epoxy to make a waterproof lining on the holes. Use that very light white powder stuff to thicken it a bit if necessary.

Then mix epoxy with hard filler to fill holes to just under the surface

then with your Dremel chamfer the edges of the hole and fill to level with epoxy and soft filler.

Finally sand smooth.

 

[oldsaltoz]

G'day Twisterowner,

I have used epoxy resin and micro fibres then coated with closed cell balloons cos I hate sanding.

First ensure the holes are clean and dry.

You will need a bit less than an egg cup of resin; using a kids paint brush coat the inside of the holes with some epoxy resin, then mix some micro fibres into the remaining resin to the consistency of a stiff toothpaste, plop this into a measuring syringe (available from any chemist), and holding the end hard up start to feed the resin mix in, working the nozzle out and the hole fills. Leave the holes a few mm short of flush.

When tacky, about 45 minutes after first mixing, you can add a little more resin and hardener mixed with ;Closed Cell Balloons' and level off with a plastic ruler or timber batten and avoid any sanding, then as final coat add 2 or 3 coats of resin wet on tacky.

When cured, wash with fresh water till the surface water no longer forms beads, a plastic kitchen scourer is good, only then can you sand it and then just to remove the high gloss, it's now ready for a coat of primer before antifouling.

I do hope this helps.

Avagoodweekend......

 

[Slow_boat]

What's wrong with plastic padding? It's cheaper and less fuss.

 

[boatbuilder]

And not waterproof!!

 

[Slow_boat]

Now that surprises me.

Okay, Milliput. About three quid a pack, easy to mix, easy to apply and dries under water. And guaranteed waterproof. Every boat should have some.

 

[boatbuilder]

If you use miliput , or any 2part epoxy stick, It will indeed cure underwater. However it is only curing itself and not bonding to the hull. Its very good in emergencies, have used it to keep a cat afoat after it sat on a large stone on a beach.
There is no shortcut to this job, if you want to get a good bond then go the route laid out above.

 

[Slow_boat]

Okay, I bow to experience. (not meant sarcasticaly)

 

[Lakesailor]

Plastic Padding Marine Filler is waterproof, but it does recommend protecting with a marine paint system below the waterline.

 

[boatbuilder]

Is it my imagination or did the above post read diferently 5 mins ago?

 

[Lakesailor]

It must be your imagination.

 

[Niander]

LolZ