GURPS Traveller and GURPS 4th Edition
So far, I haven’t seen a lot that needs interpreting for applying GURPS 4th edition rules to GURPS Traveller. (Except for weapon stats, which I will leave to the gearheads amongst us). The two I would identify are…
Specializations — The description of piloting a ship into jump space in Marc Miller’s jump space article seem to me to be as different as the other specialization of the Piloting skill described in Basic. So I would use Piloting (High Performance Spacecraft) to pilot spaceships and starships in ordinary space and Piloting (Jump) to pilot starships while jumping. This also somewhat mimics the fact that Classic Traveller and MegaTraveller had a separate Ship’s Boat skill.
This also means that a ship’s Engineer would need Mechanic (High Performance Spacecraft) and Mechanic (Jump). Similarly I would require a ship’s Navigator to need Navigation (Space) and Navigation (Jump Space).
This requires 2 skills for these ship’s positions, which I think works out well. If you only need on skill, it tempts each player to be able to do everything by adding a few skills and if you have too many, it just eats up too many points.
Blowthrough- This is more of a rule change (and one might also look at my list of other house rules for 4th Edition on this web site), but one that applies particularly to Traveller. Blowthrough (at least as it limits damage to characters) no longer exists in 4th edition. As a GM, I found that rule useful in limiting PC mortality if things didn’t go as I expected. A GM might limit any damage a PC can receive to HP x Wound Modifier.