What's the difference between a Class A and a Class B starport? 
The throws for presence of Scout and Navy bases differ, but those are game mechanics, not definitions. What the Scouts apparently figure is worth a whole separate class boils down to one single question: Whether the shipyards are capable of building both starships and non-starships or just non-starships.
The jump down to Class C is considerably broader: No yards, no maintenance, no refined fuel available.
Meanwhile, we get starports with boatyards in systems that apparently have few or no customers for their products. Either the local tech level is too low for space travel or the population is so low you wouldn't expect the amount of spaceboats in use to be able to support a boatyard.
As an example, take a look at the Zyra Cluster (Which is what I was doing when these thoughts occurred to me):
	
	
	
		
Traltha has a population of 4 million and a tech level of 6. That might be enough to support a bit of space-based exploitation (After all, a world with a diameter of 7,000 miles isn't going to have enough exploitable resources to occupy the energies of that many people, right?), but any outsider who goes to Traltha to buy a ship's boat is going to be mighty dissappointed. Zyra has 30,000 people living on a T-prime world and a TL of 7. How much space traffic is that system going to have? Or Murchison or Prilissa? Besides, I do wonder if the Scouts are really going to award a Class B rating on the strength of a yard that builds TL6 spacecraft.
Katarulu is the only one of the five that might not require some explanation. At least it has an adequate TL and the Navy for a customer. (In a way, a Class A starport on a world with a lowish population is easier to explain (sort of, anyway). at least its products can jump away on their own
).
Be that as it may, I'd like to propose that Class B starports be redefined to mean that refine fuel and maintenance is available, but no shipbuilding. That way you get:
	
	
	
		
Rather neat, eh?
The difference between starship yards and boatyards would become solely a matter of the local TL and the presense of customers. A yard would build boats if there was any local space traffic, otherwise not. A yard in a system with a tech level below stellar would require an explanation why the system was importing starship parts and assembling them, or have its starport downgraded; contrariwise a starport with stellar technology and a high population would require an explanation why it wasn't building at least spaceboats, but that's a little easier to explain.
Hans
				
			The throws for presence of Scout and Navy bases differ, but those are game mechanics, not definitions. What the Scouts apparently figure is worth a whole separate class boils down to one single question: Whether the shipyards are capable of building both starships and non-starships or just non-starships.
The jump down to Class C is considerably broader: No yards, no maintenance, no refined fuel available.
Meanwhile, we get starports with boatyards in systems that apparently have few or no customers for their products. Either the local tech level is too low for space travel or the population is so low you wouldn't expect the amount of spaceboats in use to be able to support a boatyard.
As an example, take a look at the Zyra Cluster (Which is what I was doing when these thoughts occurred to me):
		Code:
	
	Hex	World		UWP		Bases	PBG
0303	Edenelt		A4638BD-B	X	934
0305	Conway          D894586-7	S	311
0402	Leander         E695244-5		801
0403	Pepernium	D567530-3		503
0404	Traltha		B790630-6		410
0503	Raydrad         E99367A-6		303
0504	Zyra		B555448-7		301
0505	Murchison	B544433-6	N	305
0506	Hammermium	A5525AB-B	X	535
0602	Katarulu	B252665-B	X,N,W	201
0605	Prilissa	B985588-6		510
	Katarulu is the only one of the five that might not require some explanation. At least it has an adequate TL and the Navy for a customer. (In a way, a Class A starport on a world with a lowish population is easier to explain (sort of, anyway). at least its products can jump away on their own
Be that as it may, I'd like to propose that Class B starports be redefined to mean that refine fuel and maintenance is available, but no shipbuilding. That way you get:
		Code:
	
	                 Class A    Class B    Class C    Class D    Class E
Shipbuilding        x          -          -          -          -
Maintenance         x          x          -          -          -
Refined fuel        x          x          -          -          -
Repairs             x          x          x          -          -
Unrefined fuel      x          x          x          x          -
	The difference between starship yards and boatyards would become solely a matter of the local TL and the presense of customers. A yard would build boats if there was any local space traffic, otherwise not. A yard in a system with a tech level below stellar would require an explanation why the system was importing starship parts and assembling them, or have its starport downgraded; contrariwise a starport with stellar technology and a high population would require an explanation why it wasn't building at least spaceboats, but that's a little easier to explain.
Hans