Thanks to all for the help to date.
Stavros - will make sure I wear a mask - we all know of the 'mad hatters' - workers in the hat factories who worked with lead.
Derek, Tigertiger & all, I have posted a photograph. The lead sheeting plates can just be seen. The existing waterline is to the top of the first plate line. With the battery fitted the water line is level all around, however with the battery removed the water line is correct at the bow and the same (to the top of the first row of plates) at the stern. The battery I used was a small 6v 1.2 amp gel cell. I would hope to replace this with a 'c' or 'sub c' pack. The weight would be similar and again this would be on a trial and error basis.
Probably these plates have been fitted to correct a ballast problem, the previous builder has however fitted too many. I would like use Derek's suggestion of internal ballast but to attempt to remove them could damage the balsa hull.
Rick, Some of the yacht builders recommend removing lead from the keel, with a surform, didn't know these still existed.
Otherwise this is quite a tidy craft, worthy of the remedial works. I think a reasonable buy at £40(before the credit crunch). After the plate issue has been resolved the dark green underside of the hull needs re-painting dark red, and some of the handrails are in need of TLC.
The Garden Solar Light is not mounted on the deck! My photography needs to improve.
Tony