So say if you make the boat how you like it. You can rotate the image afterwards so it's facing another direction.
My advice would be play around with vertical and diagonal walls to get the right shape. For water I don't use the actual texture that is water I instead use a texture that looks like waves when blue.
The reason is I can colour wooden planks a shade lighter so it looks like it's becoming submerged but that's extra fancy.
Again see the map I made of the cruise ship for ideas, it's under MHA pack.