Thanks Wet Feet, The boat was built by Avacraft, in 1968. On inspection it looks as though the case may well be glued down. I can't see any sign of screws through the 'logs'. The only screws i can see are through the benches at the front of the case, and at the sides, through the supports there (sorry, not good with boat terms not sure what these bits are called) I've had a quick look underneath the hull and there is also some cracking in the paintwork around one of the selfbailers which may be where the water is coming in. I will enquire with the Ent Assoc, they are in Southampton now.
No Brows, Ringo is not speaking to anybody after his recent rant on the internet.