Found a beached jetski, can i take it?

[Bryan W]

i found a beached jetski the other day..its an old seadoo spx 600 i believe. it was ticketed far down the river that i found it and i think the harbor master let it go because it was "illegally parked." the ticket was dated september..which means it sat through the whole winter! so anyway, my point is can i take this thing and claim it mine? i could have sworn there was some "beached boat law" but i'm not sure.
i forgot to mention...its been registered for 2010 because it has the sticker on it..so maybe that means it hasn't been sitting that long? i don't wanna get in trouble with the law if i end up taking it. :-/
my dads a locksmith so getting it started is no prob...and my friend has an empty boat trailer too :-)
i don't think it runs because theres oil all on the inside..i don't see why i can't take it if the registration goes out of date. If i mentioned it to the police, couldn't i take it if no one claims it within X amount of days?