One good example of stealth ship is the Valour Class frigate of South African Navy.These frigates do not have funnels,but the fumes are guided underwater,both for diesels and turbines.Your ship has significant thermal signature as it is now.
as I said, this one isn't really an stealth ship, but an warship. the funnels are designed to shield some heat from the inside (cold air mixed with the hot exhaust gasses and so on) but not comparable to real stealth ships.
to ezgo: please use the new oto melara guns from the sheet I am working on
download/file.php?id=537
what you will need, are details. lots of details. you need lights, railings, rhib bay, life rafts.......
btw, the role has to be the first thing you need to think about. on the role depends the use of engines, weapons and size...... and the basic layout.