Hey Rui!
I do know about Joseph Neumyer's dioramas, he's a great technician, but this is indeed his dioramas that tought me the limitations of the boat-diorama in the open sea!
When he does a diorama with only one ship, you'll see that he puts some explosion just to off-center the boat, but in the end the boat is still more or less at the middle with decent size sea areas with quite nothing on it. Then of course he did his "duel at sea" diorama (Schnellboot vs cargo) which is perfect when it comes to action and technics, but there's still this problem of the flat area of the sea which personnally is something I do want to break. Basically, areas with nothing on it with one colour tone would tend to work so-so. it would still look like this : ___\/____\/___
I hope i can really define this a bit better, and find out the right words in english!
JB