Thanks for your replies red_green.
What I meant by saying variants was "can I add any more ship classes to the game?" but I guess from your reply, that I can't.
I suppose I'll just have to learn to start tweaking ships for myself.....
Oh i see what you meant. No your limited to these hull types-SH,PF,F,FF,DD,DW,CL,CA,NCA,BCH,CV,DN,BB,LP,BS,BT,SB,BIO,PLANET
and yea its pretty much learn as you go, cause trying to fix a spec without seeing it is just taking stabs in the dark.
I have put in a number of ships and am still learning. I believe you can add a ship in as say FedDestroyer3 but give it a DN hull. Just keep experimenting, always back up the latest working file, in case things go wrong.
Try looking at some spec files from mods like DominionWars for some examples. Wish I could better help. Too bad there isn't a utility for this stuff yet-hint, hint