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  Topic Review (Newest First)
05-22-2009 07:57 PM
Maine Sail
Originally Posted by kingcan View Post
But as DrB suggests, we're feeling a little leery of the wood/water/seacock combo and planning the fix without wood (considering brass).
I would not advise brass. Solid fiberglass is much better as it will expand and contract at nearly the same rate as the hull, will be a permanent fix that will never need replacing, and won't suffer from galvanic corrosion issues.

If you don't want to make your own backing blocks McMaster Carr sells Garolite G-10 in 1/2" and 5/8" thicknesses which is a fiberglass/epoxy pre made panels. It's pricey but amazing stuff.
05-22-2009 02:45 PM
mitiempo The best backing block for a seacock is epoxy or fibreglass epoxied to hull in my opinion. See Mainesail's how-to here :Replacing Thru-Hulls and Seacocks Photo Gallery by Maine Sailing at
05-22-2009 11:08 AM
kingcan So here's the update:

After half a day, all water stopped. Our theory (ah, theory) is that the wood backing dried out when it was on the hard, and when we put her back in, the wood swelled up with water and plugged whatever problem there was temporarily. When we picked the boat up last summer, it was already in the water, so if this had been an ongoing thing, we wouldn't have seen it. But as DrB suggests, we're feeling a little leery of the wood/water/seacock combo and planning the fix without wood (considering brass).

Our 20+ year old Raymarine ST3000 autohelm died the same day. At least it wasn't a boring day....
Thanks for the additional info everyone.

“He who loves practice without theory is like the sailor who boards ship without a rudder and compass and never knows where he may cast.” - Leonardo da Vinci
05-15-2009 11:45 PM
I don't like to use wood backing plates for below waterline

seacocks because of this very reason: Wood will eventually rot if kept wet and unprotected. A rotting base plate in a critical application can lead to a leak.

I would use a 3/8 to 1/2" thick fiberglass/epoxy plate instead. They are easy to make even with a curved contour and will be impervious to water, expand an contract similarly as the hull and strong enough to be through drilled and bolted.

05-15-2009 08:04 PM
eolon I had an almost identical problem, except with the electrical grounding plate. I noticed it weeping last year, tried a quick fix (which for some reason is never quick, and never seems to fix anything) and decided to fix it this winter.

It turns out that the blocks were pine or fir or something, and were pretty wet and soft. I replaced and bedded the new plate and used teak backing blocks, end of problem.

Best Regards,


05-15-2009 07:24 PM
sailingdog I don't think that would help, since it may not be coming through the thru-hull, but around the outside of it.
Originally Posted by moonie5961 View Post
can you not put a tapered plug into the thru hull from outside, or use a plunger like has been suggested here in the past?
05-15-2009 06:11 PM
floatsome Another possible mechanism for cause of the leak: some water got in the joint or old backing plate last summer/fall and froze during the winter, opening a lead enough to be noticeable this spring.
05-15-2009 04:23 PM
sailingdog A good fiberglass boat will have a dry bilge. It doesn't need to weep like a wooden boat does.
05-15-2009 04:11 PM
kingcan Well, bugger it.

sailingdog and DrB, thanks very much for the info. We were afraid it was a haul/replace issue but we're a bit green and not sure what's "normal"*. Luckily we're on board all week, so we'll keep a close eye.

And now we know. So thanks again.

(And no, DrB, not that type of yard. It's a "you check" yard. We checked, it seemed ok.)

**In my partner's defense, maybe *I* am not sure what's normal. the old wooden troller my dad had always had water in the bilge (and sometimes in other places), a constant diesel smell and various mechanical issues. that was par for the course. Maybe my viewpoint is a bit skewed.
05-15-2009 02:25 PM
DrB If it was me, I'd pull her and fix ASAP. If water is really coming from the crack, that could be a significant issue as it may mean that the hull is compromised.

The screws are less of an issue to fix.

Whether you need to today immediately or wait a few days, I think that you can wait a few days, but I would monitor and see how much water is coming in. If it is just a trickle, like a few gallons over 8 h, then a fully charged battery and a good bilge pump will be fine. I'd go down to the boat each day and drain the bilge into a secondary bucket. If you're getting a lot of water in, then you need to have it pulled ASAP.

I am surprised that the yard didn't catch this. When a yard typically splashes a boat, they put in and then wait a few minutes and then check all the thru-hulls and seacocks. My yard waited almost 20 minutes before they considered the boat ready to move away from the dock. They splashed me, moved me to the end of the dock and did a quick check to make sure water wasn't gushing in, moved me to the end of the lift dock, got the next boat on the truck and into the slings, came back and rechecked my boat, and then moved me away. After I was at my slip, they returned to the next boat and repeated the process.

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