Mark, I'd suspect part of what you see is not from the used boat market per se but from the crazy real estate market peaking. In the past few years there have been a lot of "get rich with real estate" scams, ergh, seminars, given. And a lot of people who shouldn't have gambled in marginal real estate did, while overextending themselves with predatory mortgages. Boom's busted now, and they are trying to call in all of their chips--which may include the boat they were told they could afford with the paper riches.
A Hinckley dropping by 40% sounds like the odd boat, i.e. way overpriced to begin with, or terribly wrong. I've noticed used boat prices weren't going UP any more but assumed it was because "the same" old boats were getting older and the Katrina/Wilma search for replacement boats cleared a number off the used market--it went up for a while. Then again, increasing petro prices are making new boats mor expensive, which should raise used boat prices.
But a lot of people believed a lot of real estate programs, foreclosures are at record levels and that should be affecting pretty much everything.