I just uploaded a pdf with house rules for starship design and combat, that I have been using for a while. They are mainly for star wars-like space opera, but I suppose it can be used in other kind of settings as well. They have grown out of a frustration that there have been no actual starship rules for BRP (or not much for science fiction at all - though River of Heaven seems to change that).
I have tried to keep the rules simple and quick, true to the nature of BRP. I have deviated somewhat from the recommendations for vehicles in the main rulebook, to make them more intuitive. Main focus is on choosing the functions needed for the ship, in a modular fashion, and adding a few specific stats. A simple scale concept is also added, though it's not entirely unproblematic.
I appreciate all comments: overall concepts, game balance, language - anything at all. (And sorry about the layout - I got a little carried away - the rules are not quite as polished as they might look...)
Download from http://ge.tt/64RnwBK1/v/0?c (ge.tt is a file hosting service without ads, that I find quite good).