If it's not the pivot point, then you need to play with how the camera sits in the boat when you first place it, finding the sweet spot. Try translating/rotating it up or down and towards the front of the boat so it only sees the bow; it may be too low or too far back or pointing towards the inside of the boat too much which is showing the water as the boat hit's the turbulance from the water. The tutorial doesn't deal with collision objects so the water WILL come through the boat...that's the way it is...you just have to aim the camera in a way that it doesn't show.