I was just thinking that it would be better to disable or remove the props. Nothing more boring than watching a big metal boat sit there and do nothing. It is just conceivable that the Israelis are going to let the Iranians “escort” the flotilla to the port and do nothing. Then while in port sink all of them dockside. Big cement bomb should just about do the trick of punching a hole in the boat without exploding and killing sailors on board.
Long floating cable pulled infront of the ships at night would foul their props and have the same effect.