Thrust Rating Brainstorm

Well, since I've kinda had Wet Thrust forced upon me (no comments from the
peanut gallery, please), I figured I might as well look at it...

It made me think about the reduction of Thrust Ratings due to damage. The
larger the ship, the harder it should be to reduce the Thrust Rating, as it
has more massive and more dispersed engine rooms. Modelling this is made
slightly more difficult by the fact that most really large ships have fairly
low Thrust Ratings to begin with.

Any ideas on how to represent this?