RE: If rules change, will you honor new rules?
BTW - neither of the two main boat racing sanctioning bodies accepts AMA insurance, so it really only covers casual recreational boater. IMPBA and NAMBA both require membership, and hence their own insurance, in order to enter a race they have sanctioned.
There are RC boats that can do over 100 mph and weigh 15 pounds or more. I guarantee they can do some damage.