It's not easy to make it look realisic, Pflow can make splashes from the bows by putting particles on the hull and making tha sea a collision spawn defletor the spawns bounce off and fall with gravity force, when they collide with the water again they can leave a shape mark on the sea surface like foamy water.
The more particles you use the better the effect but it gets very slow.
For the waves the is a Wake plugin from Blur, find it here:-
http://www.splutterfish.com/sf/WebContent/BlurPackIf you've got money to spend there are commercial plugins for sea water the claim to make ship wakes, search the net.
The attachment is one of many experiments I've tried for this kind of thing, maybe not the best but easy to find not too big a file.
I think one of the Pflow tutorials from an earlyer version of Max did something similar.
332_kXUSdSofINCcA9bTbVGH.zip