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  gelcoat sleeves in thru-hulls?

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Author Topic:   gelcoat sleeves in thru-hulls?
alkar posted 03-03-2003 09:58 AM ET (US)   Profile for alkar   Send Email to alkar  
I'm doing a fair amount of gelcoat work on my boat, and the drain tubes are already removed, so I'm wondering why I shouldn't finish the interior holes for the tubes as though they were part of the exterior of the hull. Why not drill the holes out to get a slightly larger bore and a good working surface and then finish them? Then the tubes could be reinstalled with the time-tested process, but small leakes (or subsequent tub failures) would be of less concern because the hole itself is "water-proof".
Montauk posted 03-03-2003 10:04 AM ET (US)     Profile for Montauk  Send Email to Montauk     
Contrary to belief, gelcoat is not waterproof. That is why blisters form on your gelcoat if the boat is left in the water with no bottom paint. Careful attention to caulking is all that is needed.
alkar posted 03-03-2003 12:33 PM ET (US)     Profile for alkar  Send Email to alkar     
Thank you Montauk. I have read quite a bit about gelcoat's propensity to blister, but my impression is that it takes prolonged exposure - as where water is sitting next to the fuel tank for many years. The gelcoat in my sump area, which is nearly always covered by water, it showing no sign of blistering after 14 years.

My drain tubes appear to have been properly installed by whaler, and two of them were intact and appeared well sealed when I removed them, but the surrounding wood and foam were still damp. A moisture meter and test holes confirmed that the water had not penetrated far - but it did get in. It seems like it would be worth the small additional effort it would require to create one more barrier to water intrusion. If not gelcoat, maybe something else. Your thoughts?

Tom W Clark posted 03-03-2003 12:44 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Alex,

It's a nice idea in theory, but I don't think it is practical. Gel Coat alone will not do much.

You could argue that perhaps 'glassing and gel coating the tubes would be the way to go, thus building some thickness to the wall of the tube, but what a hassle.

On early 13' and 16' hulls there were weep holes from the bow locker and the lip of the bow locker into the main part of the boat's interior. There tubes did have gel coat in there, and nothing but gel coat. It did not last long. On CSW I was able to probe those weep holes and crunch the remnants of gel coat in there with a pencil.

The real problem with sealing the drain tube holes is not what you use to seal the surface of the exposed foam. You could slather polyurethane caulk all over the new drain tubes, right? But what does that really get you? Not much, and the reason is that the problem area is where the tubes meet the hull, not the length of the tube itself.

Once water gets past the seal of the tube at its intersection with the hull skin, it's behind whatever sealant you may have put on the exposed foam there. It doesn't matter if it's gel coat or caulk.

dscew posted 03-03-2003 01:59 PM ET (US)     Profile for dscew    
I think your idea of drilling out the hole to a bit larger size would work IF you glassed the inside, not just gelcoated it. I think it would work to slather the epoxy (or whatever it is that you use with fiberglass rag) all over the inside of the hole, add the rag, slather in more epoxy, make sure its round so the tube will go back in, let it cure, and then gelcoat it. I'm not a glass expert, though, it may be wise to consult one.
Chap posted 03-03-2003 02:21 PM ET (US)     Profile for Chap  Send Email to Chap     
Hello,
How about an epoxy shaft with a hole the size of the drain tube drilled through it? Thats if you want to keep the tube brass or the tube at all. Similar to mounting an outboard and going the extra mile.
Keep the hole on the exterior of the hull the same. Hole saw, if you can get to it, the liner skin only, say 2"+-, then carve out the foam 2"+-, or sharpen a piece of pvc pipe and take out a foam core sample down to the hull skin but not through. May be tough to line up. Pour or smash in some mash epoxy, cure and drill. Finish. Install tube. Probably tough to execute though.
The hull skin and liner skin should have met where the tubes are or at least have been solid somehow. That would be some complicated mold though. How much floatation would you lose? I can feel the horsepower rating dropping already.
Still like my sponge.
Or do like doobee says and keep an eye on such things.
Thanks
Chap
AC posted 03-03-2003 02:41 PM ET (US)     Profile for AC  Send Email to AC     
Tom,
Regarding the weep holes that feed from the bow locker into the cockpit on the early 13's: My old 13's weep holes sound like they are similar to CSW - brittle and flaky gelcoat inside. What do you recommend I do to these weep holes?
NEVER SCARED posted 03-03-2003 03:39 PM ET (US)     Profile for NEVER SCARED    
I removed the engine mounting bolts on my 18' and oversized each hole. Next I dipped a pencil into a mixture of west system epoxy and coated the entire inside. This worked excellent and gives me more protection from water! A flashlight confirmed that the wood and glass is well coated.

Never scared

AC posted 03-03-2003 04:11 PM ET (US)     Profile for AC  Send Email to AC     
Never Scared,
Not sure if you were answering me or above thread, but the weep holes that Tom and I refer to are visibile from the cockpit, so I wouldn't want this cosmetic repair to show epoxy. I suppose I could bore the holes out slightly, sand, and fog with blue gelcoat spray. I welcome suggestions.
alkar posted 03-03-2003 04:41 PM ET (US)     Profile for alkar  Send Email to alkar     
You guys raise some interesting points. And glassing the holes may well be more work than it's worth. I think I'll defer the decision until after all the other major projects are done.
Tom W Clark posted 03-03-2003 05:35 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Adam,

When I was looking at the weep holes in CSW and realized that there was unprotected foam in there, I though about what to do if I had a viable 13' Whaler and wanted to seal those weep holes.

About the only thing I could think of would be to enlarge them and install some clear or white plastic tubes that could be glued in with epoxy or polyurethane caulk. Yes, you will see them but if you could get the new tubes to fit tight to the enlarged hole you could then trim them flush with the gel coat and buff the cut edge out so it was as smooth as the gel coat itself.

You would essentially be left with small visible rings in whatever color of tubing you used, but it would look clean and deliberate.

The other place on the old 13's you want to be careful with is the oar lock sockets that were installed on some models. DO NOT ever remove those pieces of hardware unless it is to fill them in. It appears as if you can unscrew the two screws holding the bronze sockets in place, but this is an illusion.

Those sockets were molded into the hull when it was laid up. The gel coat covers the entire socket and the wood screws too. Whaler used off-the-shelf bronze sockets but then added a plastic cap the the bottom of them and installed the little #8 wood screws and then laid them on the liner mold before spraying the gel coat, thus the gel coat and subsequent fiberglass totally encase the oar lock sockets.

Unfortunately, very few understand how these sockets were installed so inevitably, somebody, at some point, has come along and poked a screw driver down the sockets to see if there is a bottom or just foam. What happens is that the plastic cap at the bottom of the socket is easily damages and a perfect hole is created for water to accumulate and eventually soak into the foam.

where2 posted 03-03-2003 05:37 PM ET (US)     Profile for where2  Send Email to where2     
Taking some thoughts from the 25' out back here. Why not enlarge the holes and put Schedule 40 PVC pipe in the hole in place of the epoxy/gelcoat/brass? Keep the sunlight off it, it should be fine... The deck scuppers on the 25' CPD out back look like PVC to me...
AC posted 03-03-2003 07:48 PM ET (US)     Profile for AC  Send Email to AC     
Good idea, Tom.

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