I'm trying to make a design capable to be built in a shipyard that has retooled to a previous design. What is the formule to achieve it?
I have tried many things, but none of them seems to work. To be more clear, I want to build a colony ship using the same shipyard I used to build a light freighter.
Thanks!
For a ship to be built out a shipyard tooled for another class, two things must be true:
- The refit cost from the shipyard class to the other class must be <20% of the build cost for the shipyard class.
- The difference in size/displacement between the two classes must be <20% of the size/displacement of the shipyard class.
The refit cost to refit from Class A to Class B (in this case, Class A is the shipyard class) is the cost of all
new components on Class B which are not present on Class A, multiplied by 1.2x (i.e. there is a 20% premium), multiplied again by the relative difference in size/displacement. This latter factor is calculated as [ 1.0 + ABS(Size_B - Size_A) / Size_A ].
The most common example is to have a colony ship and a cargo freighter. Say that both displace about 40,000 tons with the colony ship being about 200 tons larger due to extra crew quarters. The colony ship costs 1500 BP and the freighter costs 500 BP. It would be impossible to build the colony ship from a yard tooled for the freighter, since the cost of the cryogenic chambers alone is greater than the entire BP cost of the freighter. However, a standard 25 kT cargo hold costs only 50 BP, so the cost to refit from a colony ship to a freighter is quite small:
- Cost of new components: 50 BP, possibly a bit more due to changes in the crew quarters layout.
- 20% premium raises this to 60 BP
- Size difference is (1 + 200/40000) = 1.005x, so the final refit cost is 60.3 BP
As this is much less than 20% of the build cost for a colony ship, a yard tooled for the colony ship can also build freighters. Again, this does not work both ways - a yard tooled for the freighter
cannot also build the colony ship.
Once you get familiar with these rules you can use them to design "bridge classes" allowing you to for example build a warship and its jump-capable variant out of the same shipyard. In the early and mid game this is essential to build all the classes you need for a strong fleet, though in the late game you can easily just throw another dozen shipyards at the problem instead.