Hi DocMatter, 

There are two ways to handle that. 

1. create a plane with a wake on it using an alpha map to hide extra space and place it slightly above the water surface.

2. Use Digital Carver's Guild Terrain Tools as covered in this link. 

Option 1 can be an animated shader or still image. That is how Mark R. did it for the boats at this link with Carrara.

Option 2 is better for still images because it literally will follow the boat around the water surface, but it may not be the look that you want. 

Mark