alternative method of plugging a hole in cockpit

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alexlago

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alternative method for plugging a hole in cockpit

Hello

When watching instructional videos about how to "plug a hole in your boat", the traditional method usually described is to stick with resin as much as (dicreasing in size) fiberglass layers on each side of the hole. then sand the whole...

Concerning cockpit, wouldn't it be simpler (and as solid) to just stick one or two layer impregnated resin fiberglass layers on each side of the hole, then fill up to the level of the original fiberglass with an epoxy+silica filler?

Thanks
 
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How will the 2 layers be flush on the finished surface & how will one be sure that the central void is fully filled?. How will the outer layer be flat, ie what will stop it dipping into the hole with nothing to support it whilst it sets? Go back to bed it is Saturday!!!!
 
Daydream believer said:
How will the 2 layers be flush on the finished surface & how will one be sure that the central void is fully filled?. How will the outer layer be flat, ie what will stop it dipping into the hole with nothing to support it whilst it sets? Go back to bed it is Saturday!!!!
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the first two layers are there to support the filler, so it doesn't matter if they are flushed with the finished surface as the filler is there for that (and for filling the central void)
I hope the outter layer will (lightly) "dip into the hole", as then it will be easier to fill up with filler...

So the process is the following :
the hole being about 6 inches in diameter in a vertical cockpit wall.

-taper both side of the hole
-glue on the inner side two layers of (300g) roving
-wait till it dries
-fill the hole from the outer side with filler till the inner taper mark (or just a bit over)
-wait it dries
-on the the outter side, cover the hole taper with roving
-finish with filler and sanding

So basically we've got a "sandwich" of filler and roving, roving supporting the repair and securing it to the wall, while filler is used to swiftly make the surface even instead of piling and piling layers of cloth...
 
Working with glass fibre in 'free space' is gross.

Do you have access to the back of the hole?
Is the hole in a flat, as in planar panel?

I would do something along the lines of laying up a couple of layers on a board, using polythene sheet as a release. Let that start to go off, then add some more layers and hold it in place behind the hole. Maybe screw a batten from the outside to hold it, props on the inside, whatever.
Let it set. Remove props and backing.
Then fill the hole initially with more glass, then filler and top coat (gel coat with wax) for cosmetics.

There are many variations on this. You can even lay up a repair piece with gelcoat on the shiny side and work from the back of the hole.

Or fit a portlight.
 
alexlago said:
lw395, this is what i'm trying NOT to do...;)
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Why not do it as lw395 suggests - it is the recommended method.
your way you are relying on a large area of filler supporting itself in the void. Surely ( if i am understanding you correctly.forgive me of i am not) the filler will want to slump , like paint. The layers of glass reinforce it to prevent this somewhat.---you could, of course, make the hole round and fit a dinghy inspection hatch and forget the whole affair. Fairly cheap and can be done in an hour and looks neat. No one will know the difference, except you!!!!!
 
alexlago said:
lw395, this is what i'm trying NOT to do...;)
Click to expand...

You're doing away with a portlight?
Fit a cave locker in its place?

The portlight was not really part of the structure, so maybe the replacement does not need to be fully structural. Mould up a flat panel to fill the hole, then glass it into place from behind with a couple of layers of resin and cloth.

All the stuff about tapering is a) to get a big gluing area and b) to have a fairly constant thickness of GRP.
b) mostly matters on a curved flexible bit of hull, you don't want a hard spot, it will raise stresses and always look wrong. On a flat, heavily built bit of cockpit, it probably won't hurt to have tapered extra layers around the edge of the repair.

Why did you not like the portlight?
 
Since that's not structural repair in the hull i would follow the easiest method without worrying so much about the method. Your steps of sandwich the filler inside the inner/outer layers of fiberglass sounds fine to me. But i would not use epoxy filler as the outer polyester fiberglass later will not stick so well on the epoxy. (remember that epoxy does sticks to polyester but not the reverse). So you can make some cheap filler with polyester and talk powder instead. But the most quick and sound and quick method would be do it with roving or mat. Unless your boat is an inch thick!
 
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