WHoa there is another option.
You can also lay down a thin layer of plaster and paint it afterwards. Alot of small scale ship dio's simulate water by laying down a thin layer of plaster inside a picture frame and then painting the low spots inbetween the waves dark blue to give the perception of depth, mid wave light blue and then the foam at the top white to give the illusion it is breaking.
Good thing is that you can set your guys in this (just fold the pants over, coat with KY Jelly which is a water based lubricant and pour over the top) and if you don't like it in the end or want your guys back you can break the plaster up, throw the pants from your figures in the wash and they should be okay and back to normal
Just a thought.
'Good people sleep soundly in their beds at night because rough men are prepared to do violence on their behalf'