Yeah.. Not a bad idea SW, just insure it to the top before pulling that plug. But you have to be real good to outsmart the insurance company and the investigators that it wasn't your fault. And that you'd be able to do only if you don't end up in concrete boots by your own boat, cuz the guys who usually do that stuf won't be very happy with a new guy in the business...
Which reminds me abourt a case when a moron bought a shipload of cheap charcoal and insured it, besides the ship and then waited for the weather to get stormy to sink it... Anyway, everything went great until the ship sunk to sum point and... stopped. Cause the charcoal usually floats big time. Anyway... The ship was svaed, along with the charcoal and the guy had to pay HUGE for the salvage operation. Oh, and he ended up in jail of course...
Seriously though, you can't just sink your ship cause you'll be sued for eco crime. But you may contact certain eco organizations or research institutes who are sinking vessels to create artifitial coral reefs...