If I had a boat with rudders worth $1000, there is absolutely no way they would be on my boat overnight, unless it was at a regatta with at least 30 others like it (even then, it would have to be a very secluded regatta site, and I'd still think twice about it).
$1000 isn't to hard to get to that value with boat parts. What would upper and lower casting (plus the rudders) cost on your cat?
