Thanks guys.
The water effect I use at the moment for jobs like this is Acrylic gel medium
In this case I masked off the base (there is a pix above) where the ship went and painted various blues/grey colours to give the impression of depth a bit.
After that was ready, basically slopped this Gel gear on, but not too thickly other wise you will get some translucent bits where the stuff at the bottom does not cure clear. In itself that sometime works as well but for the painted base to show through clear is better.
Then using the Mk1 fingers in Latex gloves (please.. this stuff is a horror to get off) and a bamboo skewer or similar work up the peaks, wakes and the like
Over exaggerate the peaks as it will settle a bit, if found that putting your whole hand on and lifting away gives a nice random effect.
The just paint up the peaks with a bit of ivory colour paint.
When happy, gloss coat the lot.
I then cut out around the masks, this is important as this stuff is quite weak and will pull away easily so cut firmly and carefully remove the masks. Then the ship was replaced into the base with some Gel around the hull to hold it in plus give some wake to work with around the hull sides.
Works ok at this scale I reckon.
Cheers Brian T