Have always thought that these ship turned spaceship things have retained too much of a "combat in a gravity field" look about them. The decks are flat and obviously set up to provide flat footing for use in a gravity field. They don't cover the other angles as would be true for a ship to fight targets anywhere in a sphere. They also have a lot of features that relate to operating in an atmosphere.
Soooo, a few concepts for your consideration?:
Maybe look to rounding off that main deck-to-hull side intersection.
Place the turrets/weapons/ directors/bridge more evenly spaced around the entire circumference of the hull, able to deal with targets coming from any direction.
Consider getting rid of the bulk of the port holes and anything that speaks too much of the sea (like the anchors, capstans, doors, etc.) and reorient some features.
Add sensors/weapons/superstructure to other surfaces, especially the bottom of the hull.
Cannibalise an old jet kit for engine exhausts out the back or, get rid of anything that speaks to a propulsion method and have it all moved by some sort of "drive" that doesn't have exhausts.
Get rid of ships davits, but reconfigure the various ships' boats to look like they operate in space.
Just some thoughts to get the old creative juices flowing, as it were.
Paul