Friday, December 28, 2012

Leaks and underwater epoxy

For the second time, I dismembered the aft starboard side of the boat to try to determine where a persistent leak was coming from. In modern fiberglass boats, keeping salt-water from entering the hull is relatively easy, but keeping rain or salt spray from getting below from the deck area is much more difficult. The hull on our boat is almost seamless. It was made in two halves which were joined down the middle - 'welded' together by resin and glass fibers. The deck, while also in one piece is pierced in hundreds of places by fasteners, windows, and hatches. One area that I had not had any issues with until now is the join between the hull and the deck. This is a flange, strongly through-bolted and bedded in a flexible compound. However it turns out that this is where the current leak was located.

Fortunately on our boat it is possible to remove panels from overhead. The Coast 34's were manufactured in one yard and sometimes fitted out - that is, they had their rigging, sails, and interiors completed, elsewhere. Unlike many mass-produced boats, the Coasts do not have a moulded interior liner, which would have made getting at the hull to deck joint virtually impossible without major surgery to the interior. Instead, I had to remove the single sideband and VHF radios, the GPS, release some wiring from its ties, and unfasten the wooden panel into which the electrical panel and radio are mounted. This allowed me to slide out one ceiling panel, which lies over the navigation station. The other panel over the quarter berth requires only removal of trim pieces and some electronic wire fasteners.

Once the panels were out, I could see that the re-bedding of the genoa track had not fixed the leak. When I had last done this, it had not been raining and I had foolishly assumed that water was getting in through the track, based on a pattern of wetness on the ceiling panels and from where it ran down the sides of the quarter berth area. I should have tested this with a bucket or two of water, but I was impatient. In fact, the work I did on the track only made things worse and I ended up re-bedding a couple of bolts in the track that I had not bedded adequately.

The real culprit turned out to be an area where the hull to deck flange was broken up by a moulded in scupper. The scupper is what drains the deck water outside and there is only one on each side. At this point the flange is not continuous and I saw patches of improperly bonded fiberglass on either side of the scupper. Either someone had tried to fix this leak before or the original glassing job was not adequate and had gradually lifted away from the hull. I could see that water was leaking from a small gap behind one of these patches where the hull and deck came together.

The fix I carried out was to cut away all loosely bonded fiberglass with large and small chisels and remove the excess sealant in this area. It would have been nice to use a small grinding wheel to really clean up the surface, but the access was too small for the smallest wheel I had as a drill attachment. This is where a Dremel type tool would have been useful. I then cleaned up the area with solvent and mixed two batches of two part underwater epoxy, which I applied and worked into the gap with a Popsicle stick and my fingers. Ordinary white vinegar can be used to clean up epoxy before it cures - very useful when your fingers are covered in the stuff.

Ideally, I would have waited for the area to dry more completely and used regular epoxy with fiberglass reinforcement. However, given the weather forecast for the next week, I would be stuck here waiting for at least that long with no guarantee I would have better conditions in the following weeks. Underwater epoxy allowed me to make a proper bond in the presence of moisture. This stuff has saved my butt (and my boat) a couple of times before and was also invaluable in repairing 'C'est La Vie' after she went on the reef in Samoa. I have applied it underwater to a damaged rudder and one of our friends applied it to underwater holes up to one inch in diameter on C'est La Vie's hull. Highly recommended for you boating toolkit.

Knock on wood, my repairs seem to be water-tight. It is now raining outside and I see no signs of water dribbling over the back of the radios or into the quarter-berth! Hooray!

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