Cygnet
The two drain holes at the back of the cockpit are leaking. The previous owner of this boat fixed with silicone from time to time but described it as a problem that needed to be revisited regularly. Has anybody ever encountered this problem before and if so I would be very greatful for your comments on how you fixed it (If it worked) I am looking for a permanent mend.
Many thanks
arni
This is a VERY critical problem. I suppose you realise that the transom is double-skinned at this point, where the drains go through. This means that if the drains are leaking, the water goes straight into the bilge! In my case I replaced the old drains with new bronze ones. This is simply a pipe, threaded on both ends. You push it through the hole, put a large nut on each side and tighten up with a good quantity of sealant. To ensure that the large nuts do not come undone I put another one on the outside, but to save space on the cockpit side, I drilled right through the nut and pipe and fitted a large split pin through it. Finally I put more sealant around the joint from inside, but if you have never tried, trust me when I tell you you need to be very small or a contortionist to get at it from inside! I recruited my wife.
150
This can also be carried out in plastic tube and fittings. 
151
i would look at another way as using plastic tube and fittings would make your boat look like it was constructed from old plumbing materials,
have you thought about clear tube and mastic. 
150
Plumbing bits are fine SAM
151
your prob right jon boy
martin hartley
On my boat the skin fittings are plastic with a large flange on the transom. The leak occurs on the inside of the cockpit with water leaking into the hull that way, rather than from the transom side. The skin fitting bridges the double skin but has no flange on the inside. Whilst the fit is fairly tight, I imagine that flexing of the hull over the years has broken the bond. My solution was simply to fill the gap with sealant. This had clearly been done before because the stuff I removed had decayed and was full of mould. This fix has lasted two years but will need doing again soon. Ideally, I should run a fillet of epoxy filler around the fitting behind the inner transom. Anyone got small hands?
Cygnet
Thanks for the replies. My problem is that water leaks from the cockpit to the bilges. It may go the other way as well but we find the water after leaving the boat on its mooring so this seems a reasonable conclusion. Martin Hartley’s seems the closest. Previous owner applied silcone as if reincarnation of Rambo! Can anyone recommend a proprietory product that is more permanent?
C.
arni
I note you are tending to go the sealant route. I STRONGLY recommend you reconsider. If this joint fails, it will sink the boat. It should be treated with the same respect as a thru-hull. You wouldn’t put a bit of pipe sealed only with sealant through your hull, would you?
martin hartley
I checked over my drains this weekend, the tubes are epoxied to the hull behind the inner transom. Presumably these have cracked over the years. If the leak is severe, then I too recommend refixing these in a permanent manner – bathroom sealant is only a short term fix. If the leak only weeps then sealant will probably do. Remember that the drains are above the waterline and only become submerged when the boat is heeled and the cockpit floods. Rainwater will also contribute. More water will drain through the drains back into the oggin than will through the leak into the hull. If the leak is small then sealant (well applied) will more than likely do. In short, the more severe the leak, the more thorough the fix should be.
arni
I have to disagree with Martin.
This may be OK if you only put the boat in the water for sailing, and dry store it. In that case the flooded bilge will only ruin your interior, not sink the boat. However, if you keep the boat on a mooring, this is what will happen:-
heavy rain will induce a lot of water into the cockpit. However, if there is a leak in the sealant round the cockpit drains, MOST of the water will go through this because it is lower than the lip of the drain pipe. (Obviously if it is really torrential, a good proportion may go out through the drains).
A week or two of this in wet weather, at the most, will flood your boat. Don’t forget also, that even in dry weather, boats passing astern will cause waves to hit the transom with some slopping through into the cockpit. If for any reason the stern is facing to windward, this will be significant (say you are on a trot, piles, or wind over tide). The more water that comes in, the lower the boat in the water. Remember you only need enough water in the bilge to make the transom drop by a few inches. Since flooded Sonatas tend to settle more at the stern, it will take a realtively small amount of water to bring the cockpit drains to the waterline. After that, it is a matter of minutes before the boat sinks.
By the way, I forgot to mention in my earlier posts that you have to put a block or spacer between the inner and out transomes at the cockpit drains so when you tighten up the nuts, it doesn’t squeeze the two faces together. I used a piece of larger pipe over the drain pipe.
150
do you mean leaking into the cockpit or below the cockpit?
Is your boat fitted with plastic flanges and tubes?