This months issue of Finescale Modeler had an article on creating wakes and bow waves for model ships.

I am not going to repeat it in detail here - it is a bit involved, and the pictures help a great deal. But essentially you cut out an index paper wave (Folded so you get two identical waves) curl it so the curve parralels the long edge, glue it in place, then coat with a mixture of gel acrylic medium and pale grey acrylic paint.

I am going to try it out on my steam powered maiden next week if I can find the time.

The Auld Grump