Oversized Drives

[Garnfellow]

GURPS Traveller: Far Trader has a design for a TL12/13, 800-ton tug with 10.6G acceleration and no jump capability; it "can push 28,685-ston load at 1.00 G."

So I went to do a MGT conversion. Assuming the tug can move a 20,000 ton ship, I sized the tug's M-drive and Power Plant for a 20,800 ton ship and Thrust-1. That results in a 208-ton TL9 M-drive and 416-ton Fusion-12 power plant. Add in fuel and crew requirements, and that's about as big an M-drive/plant combo you're going to fit into an 800 ton hull at TL12.

This all looks good. But when I go to recalculate Thrust for the tug by itself, a 208-ton M drive is 26% of an 800-ton hull: I'm off the Thrust Potential chart altogether and maybe have moved backwards in time. Is Thrust potential capped at the TL of the ship (12), or Thrust-7?

 

[AnotherDilbert]

That results in a 208-ton TL9 M-drive and ...

Is Thrust potential capped at the TL of the ship (12), or Thrust-7?

Potential is limited both by TL and size.

A TL-9 M-drive is limited to 1 G (HG, p14).

A TL-12 M-Drive is limited to 7 G (in a 208 / 7% = 2971 Dt ship or smaller).

 

[Condottiere]

There is a difference between a farm tractor and a Ferrari.

I'm not a rocket scientist, but raw horsepower should count more in space, even if you add in inefficiency, in which case you'd just extract less thrust per tonne of propulsion.

No in universe rationale has been provided beyond the rules as printed.