Sorry, I didn’t see this one.
Is the model currently waterline? If not, can you make it that way?.
There are lots of great videos online about ways to do it.
Generally the approach is to start with your base board and paint it a color that looks like deep water (dark blue or black) or shallow water (light green gray or light blue.
Make a thick piece of cardboard that is traced from the footprint of the ship.
Postion it where you want it and thumbtack it down.
At this point I really prefer to work from a photo, if available. Waves and wakes are funny things, and vary a lot.
Get some acrylic gel medium at Michaels. It comes in several thicknesses, gloss or matte. I start with the thick stuff and paint it on, shaping waves and general surface texture if appropriate.
Then you can add more paint if you want, like whitecaps or wake foam. Put on a little more, it can be the thinner stuff.
Last, pop out the cardboard and lay your little ship in. stick it down by running a little medium around the place where hull meets water.
Resin is lousy stuff in any quantity You layer it down 1/8" at a time and really have to work at not getting bubbles. It gets hot as it cures and can warp the model, and it shrinks a little making it look like it’s climbing the hull. Expensive too.
Using gel medium over paint is very easy and successful.
Stay clear of silicone sealant as well.
I hope that is helpful.
P.S. don’t worry noone responded. " Dioramas" don’t get much viewing unless you are modeling a nuclear powered, channeled and chopped, gun turret equipped armored car to haul gold!
Bill