Thanks for the tips. I "think" the weep is coming from this bolt. When I sponged the bilges dry if is from "around" here that water started bleeding in slowly. By pouring some coloured water around the bilges I tired to see whether it came out from the bottom of the bolt and it did not - I suspect the water pressure forcing the water up the hole. I could be wrong - often am!

Anyway - here are a couple of photos of the bolt in question. It is not a keel bolt but a deadwood bolt - it is under the engine and it looks very small and as you see there is hardly any head to it, so it will be hard to drive out I reckon.

PS the reason I never replaced this one was that it is one of the bolts that was not accessible during restoration as there was a wooden sleeper under it. All the keel bolts have been replaced....should I replace all the deadwood one to? There are some nasty ones that fan out around the stern post that look worryingly complicated to remove and replace.