Neville,
I have had my boat insured with a company called Porthcawl Insurance Consultants limited for a few years- they are a specialist marine insurance company telephone 01656 784866 or
http://www.porthcawl-insurance.co.uk They have been very good to deal with though havn't needed to make claims so far! They cover the boat, engine, electrics as well as public liability (Needed by my marina). They send out a range of forms which you fill in all your boats details on, have you any qualifications, how fast the boat goes, planned uses, mooring, marina or trailed, usual cruising area etc etc
As i say have found them to be nice to deal with and with what seems like a fair premium - was quoted less by some interent based firms but they wouldn't cover boats location in Republic (Lough Swilly).
Cheers and tight lines & happy boating, as a wise man once said a boat is a hole in the water into which you throw money!!!!!!! Wouldn't be without one though....
Paul