Several classes in same shipyard - trial and error only?

[vorpal+5 (OP)]

What are your tips to ease this somehow cumbersome process of getting as many ship classes as possible in the same shipyard?

[Pedroig]

Bridging Designs?

The math portion will hold true regardless, and though not up to date, with the custom module entry Iceranger's tool can both show what other ships designed can be built at a slipway tooled for the selected design, as well as take two (or more) designs and see if it can create a bridge design.  Tool here: https://aurora2.pentarch.org/index.php?topic=10999.msg126759#msg126759

For commercial ships I typically use a Liberty ship concept, so tanker, trooper, freight, collier tend to all be from single design, sometimes I can work in colonist, but in general the cost difference is too high for the displacement.

[dsedrez]

What I normally do is pick and copy the most expensive design (colonizer is good for that), reduce engineering and the endurance to the minimum (1 day or less for non-civ), put the most expensive (cost per ton) components of the other designs I want, and/or the components that many designs have in common, and then tinker around. With military ships, expensive weapons are often the way to go. For civilian, putting some colonizer modules can help. Often the biggest problem are the engines, if the other designs use different ones.