Another "quirk" of the upgrade system in the game. Some shipyards (levels) cannot build some ship types, especially civilian ships which obsolete the previous version (as opposed to 2 levels in warships).
As an example, if you start the game at Supreme tech level you'll see you can't build some ship types. Since Shipyard I can only build ships up to tech level 4, (for example) the Cardassian's Shipyard I can't build any Colony Ships and Transports. Since you're at tech level 9, you get access to Colony Ship III, which obsoletes the II, which is level 4 but you can't now build; so you can't build *any* colony ships. Same happens with Transports, and Cruisers (IV obsoletes II [lvl4]); they require Shipyard III.
Now, this particular situation could be solved by having a Shipyard III in the homesystem, but that doesn't really solve the issue. In any other system, you can't build some ship types in lower level shipyards.

I was never a fan of having tech limits for shipyards. I think the improved efficiency/output is enough.

Ok. Will take care of that.

Maybe instead of MaxTechLevel, we could have ships have a property like shipSize, and shipyards would be limited by MaxShipSize.
Shipyard Is would build ships size zero, shipyards II up to size 1, shipyards III up to size 2, and fleetyards up to size 3.
For example, Colony Ship I would be size zero, CS II size 1, and CS III size 2. The Tactical Cruiser and equivalents would be size 3.
Doesn't really have to be about size, could be something general like Level (not tech level though).

Level and tech level could be easily confused by the casual player. I could see the forums being bombarded by questions over why someone can't build ship xyz.

Size would probably be a better way of doing it, although we could also end up with people discussing about which ship is bigger. We're Trekkies, afterall.

Yeah, but one line in their stats saying "Buildable by: Medium Shipyard" would solve the issue.

Or we could remove any such restrictions and there would be no confusion...

I think the icemans idea is better.

@ mattress

well to discuss which ship is bigger would be clearly untrekky. The biggest ship is the soverein followed closely by galaxy. Also this isn't about the biggest ship, but about the most complex one. Thats why defiant should need a large shipyard, while galaxy would need a medium (for example).

I have actually removed the restrictions already, it was just another idea on top of that