Re: spaceship was rather more submarine-ish
Spaceships and deep mission hidden nuclear subs are somewhat similar:
* You need to bring all your own food and energy (subs can process seawater)
* No easy communications with base
* Electronic sensors rather than looking out the window (nuke subs too deep for periscope)
* No easy way to take on or let off passengers.
* Special suit to go outside (nuke subs too deep for frogmen), aka EVA.
* Mission of a year without surfacing possible for sub
* X Y Z, 3D movement in a battle (Curiously many Star Trek episodes are rather 2D).
Stick a nuke sub in space with a few modifications and drive system replaced ion drive, ballast tanks replaced by reaction "fuel" etc.
Space ship shell: 1 atmosphere of pressure from inside. About 1 Atm for sub at 7m or maybe 10m, and 300 at metres, thirty atmospheres.
Apart from actually putting one in space to start with and shielding from Cosmic rays etc (water + double hull works!), a space ship is maybe easier than a stealth nuke sub.
I deliberately watched "Das Boot" to get some ideas about what a primitive 1st starship might be like compared to the ones Aliens had for 4000 years... Writing a series starting with 1st Contact of a different nature.