I hate the island map 

Well, when you beach a ship in real life. You damage the underside of the hull depending on the speed you hit the coast.


Now imaging a sub crashing into the ground.

Now imaging a car crashing into the side of a slope after falling off a bridge.



Now imagine a sub sized car crumpling after hitting the ocean floor by the coast. 

Perhaps they should make it as a one off damage amount when you initially hit, depending on your speed. Instead of constantly damaging your ship once you are beeched, while your engines are running.