Are there Gap insurance policies available for boats? I have a policy on my bike that covers the difference between the "actual cash value" that the blue books show and the difference on the loan. It was pretty cheap, just a few hundred bucks one time deal.

The difference between what I owe on my boat and what the books are saying it is worth is getting to be a fair amount. Wondered if this might be a cheaper alternative to an "agreed value" policy?