Try it, its fun.
The boat skips along the water like skipping a stone accross a pond after a certain speed. If you hit/skip off of the water at just the right angle and speed you'll be flying for like 30 to 100 KM before you spashdown
Hit it wrong and you'll be going very deep, very fast, kinda of like that one picture i got up there.
Sub' behaves really weird, and you really dont even need to engage the engine in any speed. Just sit there and wait. The boat will gradually (and exponentially) pick up speed without putting any commands to the engine at all.