
The objects have to go on land but there are ways around it . Ships beached , Ships run aground , Planes etc etc .

Place the shipon water no problem . Build the sea floor up with the terrain editor . Place the ship on the raised seabed . Lower the seabed with the terrain editor .
No fps loss . Can you collide with it ? Yes . Can you destroy it ? I havnt tried .

Sunken block ships

The game did drop to 55 fps from 58 fps when close to all these ships .