I use a large, very large, sponge from Home Depot, and pill it straight up to get the water effect, the you pain on the white caps (having decided which way the wind is blowing) after you pain the water. Varying sponge sizes give different results. I did the same technique for a Lunar Diorama of the L.E.M. on the surface of the moon. The ship is built )usually) as a waterline model, so you trace the hull, knowing where not to put the plaster, ships have a "cradle' of water they set in, which I seldom see duplicated properly, but this is just a lack of understanding of what displacing water actually is, and how a moving displacement of water causes a ship to actually drop do, a few feet if it is an Ocean Liner.