[dogscoff]

I think it's just space yard ability that the game won't allow you to have more than one of on a planet. The repair ability is completely seperate from the spaceyard ability, it just happens that in the standard game they are both used on the same facility. There's nothing to stop modding a "repair" facility into the game, which can fix ships but not build them.

multiple facilities with repair abilities on a single planet *do* stack their repairs, as proven by the cultural centrews in Proportions mod.

Another way to get the effect you want (sort of) is to build spaceyards on a planet and all of it's moons.