Ship class compatibility

[Nibelung44 (OP)]

Hi,

I don't understand how to determine before hand when 2 class will be compatible, for the same shipyard... I have a weird (serendipitous) case happening to me: I realized that the SY handling my 75.000 tons tugs, made mostly of engines, group jump engine and a tractor beam can also build the 75.000 tons freighter ships, made mostly of cargo holds! Is that not weird? Is the criteria only based on the price of differing items, and as cargo holds are cheap, it makes the ship compatible?

[Paul M]

If you look in the "class design" page -- "DAC/Rank/Info" tab you see a window "Eligable additional classes ..."

That window tells you which ships you can co-build with this class.  It is entirely cost based and yes serendipity happens.  It is often the case I can build all 4 of a set of designs but only if I pick the right one to tool the shipyard for.  Or I get 3 of 4 and have to retool for the last.  The best way to increase your chance is to keep as many things standard as possible between ships you want to co-build.

[Maltay]

Hi,

I don't understand how to determine before hand when 2 class will be compatible, for the same shipyard... I have a weird (serendipitous) case happening to me: I realized that the SY handling my 75.000 tons tugs, made mostly of engines, group jump engine and a tractor beam can also build the 75.000 tons freighter ships, made mostly of cargo holds! Is that not weird? Is the criteria only based on the price of differing items, and as cargo holds are cheap, it makes the ship compatible?

I believe the logic is the following.  The refit price from design A to B must be less than or equal to 20% the cost of building design A.  This lets you use a Shipyard tooled for design A to build both designs A and B.

[Prince of Space]

If you want to plan out your classes from the beginning to take advantage of the dual use shipyards feature, I would refer you to metallax's post here:

The base cost of a refit is the total cost of any components that have to be added to the original design in order to create the new one. Any components that are removed play no part in the cost. To this base cost are applied two modifiers, one is a modifier based upon any change in tonnage between the two classes, iirc this is a flat 1 BP per 10 tons difference in size. The second is a refit overhead cost modifier of 25% that is applied to the base cost. For a ship to be valid for building at a shipyard tooled for another class, this refit cost needs to be 20% or less of the cost of the tooled class.

Generally if your classes are the same size (as yours are), the primary class is expensive (as mostly-engine tugs tend to be), and the parts unique to the secondary are sufficiently cheap per ton (as cargo holds definitely are), it will probably work out. The real trick is getting a secondary class that's radically different but not a freighter. I've had some luck making jump capable troop transports that can be built in tug-tooled yards, and jump gate constructors that can be built alongside my tankers.

[Maltay]

Someone had the trick of designing a ship with both geo and grav sensors (i.e., design A).  Then, making two more designs, one with only the geo sensor (i.e., design B) and one with only the grav sensor (i.e., design C).  This let him tool a shipyard for design A and build both designs B and C from that shipyard as he kept the refit cost from designs B or C back to design A less than 20% the cost of design A.

[Nibelung44 (OP)]

sounds clever, BUT it would mean that your geo are military in this case...

[Brian Neumann]

sounds clever, BUT it would mean that your geo are military in this case...

Not automatically, as long as the ships were basically a civilian design with only the grav sensors being a military system then the geo survey ships would still be civilian.  They can be built in a military yard, but the design itself is civilian and all the actual ships would be civilian.  The downside to this approach is that military yards are generally harder to expand for any given size so you will not be building as many ships in the same time period due to having fewer slips to build with.  You can get around this by using your construction factories to build as much of the ship as possible (sensors, engines, crew quarters, etc.)

Brian