A Slow Leak

11-12-2019 (see 2024 update below)

 What do you do when the boat develops a 1-2 gallon per day leak, where you can't get to it, and it isn't time to haul for a year? The F-24 is a trimaran and cannot sink due to main hull flooding. Add that there is nothing other than fiberglass below the probably flooding limit (no wood and no wiring to speak of). Most people would just let the sump pump handle it. Except there is not sump pump.

As an added complication, the sump is only 3/4-inch deep before it reaches the level of the floor. On the other hand, the floor is a bath tub-like hull liner that unless holed, can easily manage 6 inches of flooding.

First, you plug any holes you can reach with underwater cure epoxy. No kidding, the stuff really does work, and I'll be doing a review for Practical Sailor soon. 

I used JB Waterweld. Scrub the area clean, but it does not need to be dry. Wet you hands. Sounds funny, but do this or it will stick to you more than the boat, which doesn't work. Cut off as much as you need and mix by kneading. rolling between your palms and folding can also work. Then press it into the hole with your fingers, with special attention to rubbing down the edges. This takes a few minutes of steady, gentle rubbing. You have to move the water out of the bond area. But within a few minutes it will be sticking well everywhere you rubbed. Keep rubbing it down for a few more minutes, until you can feel it begin to firm, which takes about 10 minutes. It will be hard within an hour.

It is not as strong as conventional epoxy, but it is strong enough for the purpose and may be permanent. 

Unlike conventional epoxies, it does not generate a run-away thermal reaction and over heat. Underwater there is cooling, of course, but even in the air it will not seriously exothermic. In fact, I know often use Splash Zone for certain filling applications, for example around through bolts, because it tolerates moisture in the laminate, because it does not exotherm, and because the cure is also relativly quick.

Then you add a sump pump. I went with something smaller than the standard Rule pumps, because I wanted to such lower and because rate was not that important to me. This one will remove about 2 gpm through a 1/2-inch ID hose, which is what I had in mind. I mounted it to an aluminum bridge, which I bonded to the hull with ... underwater epoxy.

I played with micro switches that would activate the pump at lower water levels than the standard 2-inch on, 3/4-inch off settings, but found them unreliable. So I went with a rule switch which I mounted with ... underwater epoxy.

I then added a sub-panel. I had some other lighting circuits that needed straightened out too.  A piece of Coosa Board, a terminal block, and a bunch of crimps did the job. The water hose was relocated later. The hose ties into the sink drain with a through-tee, so no added through hulls. This also gave me a chance to clean up the hose runs so that there are no low spots that can freeze; all of the water drains either to the sump or overboard.

The timer is the neat twist. I wanted the pump to have a chance to keep up with small leaks, before the water reached 2 inches, so I set the timer to trigger the pump for 1 minute every 24 hours, but I can adjust that if the level rises.

 And so far (4 weeks) this seems to be working nicely. I did jump last time I was sailing and the sump pump came on. Surely, I have a leak! But it was simply the scheduled 1-minute run time.

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Coosa Board Bluewater 26 is a fiber reinforced (several layers of woven cloth, just below the top and bottom surfaces) polyurethane foam that is lighter than plywood and will not rot, but not quite as strong. It sort of holds screws, but not like wood. It is MUCH stronger than non-reinforced foam, nearly as strong as plywood. It is normally laminated with fiberglass for structural use, but not always. It's really neat for fabricating small parts that need some strength and which you will glass over. Little flanges. Shelves. Braces.

4-2-2024 

Five years later and still holding. In fact, I did a bunch of tests for PS. The winners were Splash Zone from Pettit (strongest) and JB Waterweld (fastest plugging). The Waterweld is still holding, in part because we could never find the source of the leak from the outside. Amazing stuff, I will always keep a package handy in the future.

The pump and timer are doing fine. With only minute of run time per day there is little wear. It will move more water, however, when I clean the bilge, for example.