Limber Holes

Stemar

Stemar

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A friend wants me to help with drilling limber holes in a couple of ribs or, possibly more correctly, strengthening webs of his GRP boat.

It seems, without having delved too deeply, that they are likely either to be hollow GRP or GRP laid up over a wooden or foam former. If so, it will be necessary to seal the holes to keep things dry inside the webs. I can see four possibilities:

1. Paint this inside of the hole with epoxy. Not sure this can be guaranteed waterproof and, if the webs are hollow, a non-starter.
2. Epoxy a bit of copper water pipe in the hole. Easy, got the materials, but would the different coefficient of expansion be a problem?
3. Epoxy a bit of plastic water pipe - Hep2O or similar. As 2, and the coefficient of expansion should be similar to GRP, but will GRP stick it reliably?
4. Use GRP tube. Ideal solution, but where might I find it in the quantity I need (no more than a foot or so) at a sensible price?

Any thoughts? Is there a killer solution I'm completely missing?

Thanks in advance
 
Isn't the best approach the same as is usual when fitting an item of deck hardware on a balsa cored deck? Drill a larger hole than you want, fill it with epoxy resin, leveling it off to match the deck level, let it set, then drill the correct size hole through the solid plug.
 
maby said:
Isn't the best approach the same as is usual when fitting an item of deck hardware on a balsa cored deck? Drill a larger hole than you want, fill it with epoxy resin, leveling it off to match the deck level, let it set, then drill the correct size hole through the solid plug.
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That could be tricky if, as suggested, the frames are hollow.
I'm sure that if necessary you could easily make your own GRP or epoxy tube, using a cardboard, or similar, former.
 
Drill a larger hole than you want, fill it with epoxy resin, leveling it off to match the deck level, let it set, then drill the correct size hole through the solid plug.
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That could have possibilities.

http://www.sandpiperaerials.co.uk/in...tpj7i4it895bo2
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That could be interesting, but for some reason the work web nanny blocks the site as malicious. I wonder if they've been hacked? I'm a bit reluctant to visit from home now.

Alan ashore said:
'cos he wants to keep the water out of the inside of the webs, not just out of the laminate
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You got it!

any thoughts re water pipe, copper, hep2o type or upvc? Does epoxy stick to UPVC reliably enough for this application?

I suppose I could drill ovesize for a tube and slather the tube in glass cloth & epoxy before shoving it in. That way, it doesn't matter if the tube doesn't stick too well.
 
Stemar said:
That could be interesting, but for some reason the work web nanny blocks the site as malicious. I wonder if they've been hacked? I'm a bit reluctant to visit from home now.
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I'm at work and our firewall seems happy enough with it. No obvious malicious signs.

The link is to a half-inch GRP tube, intended for building radio aerials.

Pete
 
Lodesman77 said:
Glass fibre tubular sail batten? Found in most chandlers...

Also: http://www.ecfibreglasssupplies.co.uk/c-533-fibreglass-carbon-fibre-rods-tubes.aspx

http://www.ecfibreglasssupplies.co.uk/p-659-polyester-glassfibre-tube-254mm-x-194mm.aspx
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Thanks - that looks like a useful place to know about! I think the 25mm may be a bit big as it's to go through structural webs on the hull, but the 12.7mm, 8.5mm internal should be fine as we're only talking about the water that comes in when withdrawing the log impellor and the time to drain it isn't critical.
 
Old fibreglass hollow fishing rod off e bay should give enough to do a few limber holes and once lightly sanded epoxy will stick to it like stuff to a blanket.

Pete
 
Stemar said:
Thanks - that looks like a useful place to know about! I think the 25mm may be a bit big as it's to go through structural webs on the hull, but the 12.7mm, 8.5mm internal should be fine as we're only talking about the water that comes in when withdrawing the log impellor and the time to drain it isn't critical.
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Ok, so now we have got the bottom of it. Your friend wants you to do something to his boat which is both laborious and potentially damaging just so that he can lazily pump out the water electrically. Couldn't he just use a hand-bailer and sponge in the area where this water is confined by design? My Dufour Classic 30 is exactly the same and I think the feature is beneficial rather than inconvenient, as the traces of salt are only in one section of bilge and not spread through the rest, allowing them to remain dry even in conditions of humidity.
 
Spirit of Glenans said:
Ok, so now we have got the bottom of it. Your friend wants you to do something to his boat which is both laborious and potentially damaging just so that he can lazily pump out the water electrically. Couldn't he just use a hand-bailer and sponge in the area where this water is confined by design? My Dufour Classic 30 is exactly the same and I think the feature is beneficial rather than inconvenient, as the traces of salt are only in one section of bilge and not spread through the rest, allowing them to remain dry even in conditions of humidity.
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I agree. For all the water that's going to come in on the occasional impeller withdrawal, a sponge would be much simpler, and save any possible weakening of the frames.
 
You can manufacture the tube on the job or at home.

Last time I did this I used backing rod (a solid white foam rod) available in 6 and 12 mm diameter from plumbing suppliers or hardware shops.

Wrap the foam in silicon craft tape and apply epoxy and cloth, the tape stops it sticking, or, simply coat the rod without the tape, lever for 24 hours or untill fully cured ann a bit solvent through it, the foam will desolve leaving you with a tube.

An alternative is to use electrical conduit, cut to length, taper the ends to almost nothing and insert with a mix of resin and Micro-fibres, after wetting the inside with resin, finaly run a little resin around the ends to seal them with smooth finish.

Good luck and fair winds. :)
 
While I agree that if the only issue is really the water from putting the log in and out, it doesn't seem worth it.

I would say however that I've owned two boats with flattish bilges and the typical matrix of floors and stringers (i.e. transverse and longitudinal webs in the OP's terms).

One boat had limber holes connecting all the "cells of the matrix". The other boat had no limber holes. Boats being boats and water being water, we spent far too much time on the latter boat with the floorboards up, sponging out. Especially of course in unpleasant weather when you would rather leave them screwed down.

A.
 
Spirit of Glenans said:
Ok, so now we have got the bottom of it. Your friend wants you to do something to his boat which is both laborious and potentially damaging just so that he can lazily pump out the water electrically. Couldn't he just use a hand-bailer and sponge in the area where this water is confined by design? My Dufour Classic 30 is exactly the same and I think the feature is beneficial rather than inconvenient, as the traces of salt are only in one section of bilge and not spread through the rest, allowing them to remain dry even in conditions of humidity.
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Well, yes, but he does have an excuse - he's completely blind, so mopping up is a bit harder for him than for most of us. In spite of that, he pulls his weight for everything. The first time I sailed with him, he went on the deck of his Trapper to put his main away using sail ties - no lazyjacks - in 30+ knots of wind and a sea to match. I reckon he was steadier up there than I would have been.

The point about keeping the salt in one area is a valid one that I'll mention to him.
 
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