I have added the changes for freighters and colony ships to the next version.
Tech System Changes
1) Cargo Holds are now 100 HS instead of 10 HS. Cost, crew, etc is exactly as before. Everything that can be transported requires the same amount of cargo holds as before with the exception of minerals. A cargo hold can now carry 2500 tons of minerals instead of 200 tons.
2) Cryogenic Transport Modules are now 50 HS instead of 10 HS. Cost, crew, etc is exactly as before.
3) A new type of engine has been added. Compared to the old Ship Engine (now Military Engine), it is 25 HS compared to 5 HS and costs twenty percent more. However, it produces two and a half times more power, uses only one quarter the fuel and only needs the same crew.
As a comparison, the Commonwealth Magneto Plasma Drive is 5 HS, Power output 80, Cost 40, Crew 25, Fuel Efficiency 0.6, Fuel Use per hour : 4.8 Litres
The Commonwealth Commercial Magneto Plasma Drive is 25 HS, Power output 200, Cost 50, Crew 25, Fuel Efficiency 0.06, Fuel Use per hour: 1.2 Litres
Comparing per HS instead of per engine the comparison is:
Military Drive: Power Output 16, Cost 8, Crew 5, Fuel Use Per Hour: 0.96 litres
Commercial Drive: Power Output 8, Cost 2, Crew 1, Fuel Use Per Hour: 0.048 litres
Commercial Shipyards
Because of the above, some changes are needed to shipyards. A new Commercial Shipyard has been added and the existing Shipyard becomes a Military Shipyard. Shipyards function as before with the following exceptions:
1) Expansion of Commercial Shipyards costs only one tenth that of Military Shipyards. For example, adding 2000 tons of capacity to a Military Shipyard would cost 480 BP. For a Commercial Shipyard it would only cost 48 BP (and use 24 Duranium and 24 Neutronium). Retooling costs are the same as before.
2) Commercial Shipyards require only one tenth of the manpower of Military Shipyards for their size. Note that as commercial ships will generally not be ten times larger than before, this actually makes building Commercial Shipyards easier than at the moment in relative terms compared to Military Shipyards. An Empire will be able to expand its ability to build commercial shipping more quickly than in the past.
3) The modification rate of commercial shipyards is based on one tenth their capacity, although as the cost of increase is also one tenth of normal, this will work out to a similar expansion rate in percentage terms as military shipyards. Without this restriction Commercial Shipyards would grow amazingly quickly due to the faster growth rates for larger shipyards.
4) The Build Rate of freighters is based on one quarter of their size (see the later post in this thread for an explanation).
Maintenance Changes
To make things easier, all freighters and colony ships will no longer require maintenance as long as their design includes a full size engineering spaces. This means there is no longer any need for Commercial Freight Facilities. The maintenance requirements of Aurora are intended to simulate the logistical difficulties of long-range surveying, empire building and fighting wars. As freighters can't carry missiles and colony ships can't carry troops, I decided to remove the minimal maintenance requirements for the routine internal movements of freight and colonists.
Possible Additional Changes
Now I have changed freighters and colony ships to much larger hulls and added the necessary shipyard support, I find myself wondering whether I should extend the same principles to Terraformers, Construction Ships, Fuel Harvesters, etc. I originally sized their components based on likely shipyards sizes so they could actually be built. That is no longer a restriction so I probably should up their sizes too to a more reasonable level. I probably should also make jump gate construction easier because jump gates will be necessary for almost all freighters and colony ship traffic. I have considered two options. Firstly reducing the time required for each gate to be built or secondly making construction modules much larger (x10 or even x20) with a slightly longer construction time but removing the need for jump gate components. The latter would remove an significant element of micromanagement from the game.
Steve