I've had a fair bit of water come aboard in the last couple of legs and think I've located the problem. The drain hole on the gunnel just forward of the winch, which is the only drain hole and it could be located a bit better as when at anchor the water pools closer to the winch. but I digress. Anyway I was probing inside this drain hole and found a small hole inside the drain on that I could feed the probe wire into. It seems that between the top join on the toe fair and the bonding fillet between the deck and hull on the inside there is a cavity or maybe small cavities. bit hard to te without grinding the whole thing to bits. Anyway with the amount of water running down the deck trying to get out through this one and only little hole I imagine there is a fair bit of pressure forcing the water through.
I bought a round bastard file and increased the hole size and fitted a piece of tube. I was going to source some fibreglass tube but found an old VHF antenna that appears to be carbon fibre or similar so I cut some of that and fitted it in the hole with epoxy filler ( only epoxy I had ) leaving it protruding a few ml outboard so the water doesn't stain the hull ( something I read somewhere on this site ) and hopefully I will now have a dry bunk.
I was surprising the amount of water that was getting in. after between 24 and 48 hrs offshore in moderate to heavy conditions I was spounging about 4lt or more from under my bunk in my food locker.