You have a ship that is absolutely vital to getting the survey fleet home, but it is forced to sit idle for long periods of time, so what do you do?
1) Have it go back and forth across the warp point every day or so, relaying messages if possible.
2) Have it go off of the warp point and sit, drive field down.
3) Equip it with survey instruments of its own, so it can join the fun.
4) Have it employed somewhere else, hopefully remembering to send it back by the time the survey is completed.
5) Other
What are good secondary roles for the Jump Tender:
1) Warship (offensive)
2) Warship Point defense escort
3) supply depot
4) Good sensors/scout
5) independant survey ship
6) Comm relay
How do you employ Jump Tenders:
1) They always escort the convoys, so they always have to as fast as or faster than the fleet they escort.
2) They are stationed at a warp point for long periods, allowing continuous communications and transits when convenient.
How big should the Survey Jump Tenders be?
1) Small as possible, 75 HS. Cheap as possible.
2) Build them big enough to allow freighters that can transport a factory through, and build the survey ships big too.
I was not sure whether to put this in Ship Design or Tactics, but it goes to overall strategy more than just ship design, and strategic questions. I figure an Advanced Tactical Command Academy will also deal with strategic questions, technology comparisons, good research paths, etc...
By building small jump tenders you can afford to use them as communications relays. But they don't help with the economic growth part, except maybe allowing small colony ships and troop transports with Engineerig divisions to move around.