If I put a single small anti-missile missile launcher on my tanker it is no longer considered a noncombatant since the game has no way of knowing I'm not going to use that launcher offensively. What is the tanker not being considered a noncombatant costing me?
Just going from memory, there are three classifications:
1. "Freighter" (or commercial), whatever. This classification requires no weapons or large sensors, and at least some cargo holds or colonist transport units. This type of unit can perform the equivalent of an overhaul at the commercial freight facility instantaneously.
2. Noncombatant. This classification is for unarmed units that don't meet the requirements of classification #1. These units cannot use a commercial freighter facility and thus must do an overhaul at a world with maintenance facilities to wind back their maintenance clock. However, because they are classified as noncombatants, their clock gets rewound faster than an armed ship.
3. Normal (warship). Armed ships, and/or ships with large sensor arrays. These ships must overhaul at planets with maintenance facilities and take longer to wind back their clocks.
Kurt