Chartering my boat?

I would agree with Stefan with regards to the insurance.  It is unusual for an insurance comapny to be able to provide cover for something you do not own.  I would check the charterer's policy very carefully if I were you.

If they are not covered, then it is up to you, as the boat's owner, to provide the cover.  Most policies would exclude cover for you to charter or hire your boat, but I would advise that you check with your insurance company.

I've got a kite that has only been used for 1 4day event and is in very good condition, I've also got a good jib.  The dubious bit is the main (which I've just had repaired) but they said that they thought it would be fine as mains tend to last for ages.

Couple of hundred quid sounds fairly cheap. 

How about asking them to buy a new Kite for you instead (that they can use at the event).  Then they have paid for the most perishable bit.  (insist it is repaired if damaged at the event).  Then they then have some "buy in" to keeping the boat in one piece.

By the way, anyone want to BUY my boat ?

I think if its for the 2 week period (they may train it in before) £200 would seem reasonable if you included a trailer and sails (as these are the 2 main 'perishable' items- ie most affected by wear and tear). And Bandol is a long slog to get to, so its not the same as charging them £200 to race it round your local pond.