When you first acquire a vessel, you must roll on the Voidship origins table below - if you are not happy with your result, you can pay Wealth equal to the vessel's Rarity to re-roll, but you must take the second result.
Enlarged Cargo Hold
High Powered Engines
Observation Dome
Ostentatious Construction
Reinforced Bulkheads
Sturdy Construction
Archeotech Systems (Imperium-aligned vessels only)
Armoured Prow (Ork and Navis Imperialis only)
Tenebro-Maze (Rogue Traders only)
Xenophilious (Rogue Traders only)
Throughout your command, you will have the opportunity to develop your ship further, through 'Campaign Traits'. These are acquired by accruing Renown, which can then be spent in similar manner to the purchasing of Ability/Skill increases or Talents with XP.
The Size of a vessel dictates the total number of Traits it can have. If you are at the maximum number of Traits, you can replace one Campaign Trait with another - you can never replace a ship's Origin Trait.
Tiny: 1
Small: 2
Medium: 3
Large: 4
Huge: 5
Gargantuan: 6
All members of a Faction (both Agents and Threats alike) gain the relevant Faction Trait(s) for their Faction / Species.