Watching how the boats are behaving, they follow the path all the way to the sea floor to where the signal was. They do slow their decent just before touching the water. The chute doesnt detach until the boat hits the sea floor. Sometimes they stick to the sea floor, especially the tugs. Any chance of having the boat prefabs detach sooner. It may be a FP thing too, when you just f1 spawn one in, they rise from the sea floor.