>>95955615
I used balsa wood, then glue ship down and applied filler or a mixture of PVA + Baking soda to get a wave texture.
Size wise around 1" by 2.5" bases, but whatever works for the ship size. If the rule set uses tokens you might want some space on your bases for tokens.

Can have a look at War by Sail, or Close Action if you want something more hex based and in-depth. Fire as She Bears is also popular, or maybe Black Sails for something very arcadey and not really taking into account actual ships sailing. I think most of these are in the OP folders