Didn't see anything on shipyard sponsorship distance efficiency so I did a little experimentation and figured out that up to 6 hexes away gives no penalty to production, beyond 6 hexes seems to give ~10% penalty (90%@7,80%@6 etc) so at 16 hexes or further you only get 1 production from a planet regardless of it's actual output.

Haven't taken a real close look at tech trees or anything to see if there are any technologies that affect this.  If anyone has more information I'd like to know if there are any ways to extend the range.

 Edit: Efficiency, in the Pragmatism tree, increases the range to 12 squares before decay, according to the description, will have to unlock it to test further.