D6 Star Trek

The D6 System is a natural choice for space opera games, largely because of the popularity of the old D6 Star Wars RPG. Several years ago gamer Craig Griswold came up with some conversions of that game to other sf universes, like Doctor Who and Star Trek. He posted them on his Hyperspace Crossroads site which is now only avalable via the Wayback Machine. The Trek material has character Templates, equipment  and some new rules for handling Warp drive and those exploding bridge consoles. It was designed using the D6SW rules, so they would need to be tweaked to work with the free OGL D6 rules which are different in many places. But they're similar enough that these write-ups are still useful. I've always thought that the D6 System is a great match for a ST game and this material is a good place to start. To give you an idea of what's there, here are the stats for the TOS version of the venerable U.S.S. Enterprise.

Starship: U.S.S. Enterprise NCC-1701
Craft: Federation Starship Constitution Class
Type: Exploratory Starship
Scale: Capital
Length: 288.6m, Height: 72.6m, Width: 127.1m
Crew: 430, gunners: (?)
skeleton: 250, +5
Crew Skill: varies
Passengers: 500
Cargo Capacity: ?
Consumables: 3 years
Cost: not available for sale
Warp/Hyperdrive Multiplier: x1 (cruise x3)
Hyperdrive Backup: N/A
Nav Computer: Yes
Maneuverability: 1D+1
Space: 5
Hull: 3D
Shields: 2D+2 (see special shields rules)
Sensors:
Passive: 50 / 1D
Scan: 100 / 2D
Search: 200 / 3D
Focus: 7 / 3D+2

Weapons:

* Phaser Banks: 3
Fire Arc: Forward, Right, Left
Crew: 4
Scale: Capital
Skill: Capital Ship Gunnery
Fire Control: 4D
Space Range: 3-15 / 35 / 75
Atmosphere Range: 300m-1.5 km / 3.5 km / 7.5 km
Damage: 4D (variable settings)

* Photon Torpedo Launchers: 2
Fire Arc: Forward
Crew: 6
Scale: Capital
Skill: Capital Ship Gunnery
Fire Control: 3D+1
Space Range: 2-12 / 30 / 60
Atmosphere Range: 200m-1.2 km / 3 km / 7 km
Damage: 9D

* Tractor Beam Arrays: 1
Fire Arc: Forward
Crew: 3
Scale: Capital
Skill: Capital Ship Gunnery
Fire Control: 2D+1
Space Range: 1-5 / 15 / 30
Atmosphere Range: 100-500m / 1.5km / 3 km
Damage: 4D