Why can't I refit / build these two ships at the same yard?

[scvn2812 (OP)]

I have a missile boat design that I've been continually making minor updates to. The most recent tweak was to swap out its gamma shields for deltas. That's it. That's all I did to it aside from redesignate it from a fast attack craft to a missile boat.

I was even able to refit this thing from ion to fusion drive at a 75% and change fee without issue.

Skadi IIb class Attack Craft    2,400 tons     257 Crew     483.1 BP      TCS 48  TH 56  EM 120
3333 km/s     Armour 2-15     Shields 4-300     Sensors 6/6/0/0     Damage Control Rating 1     PPV 12
Maint Life 3.41 Years     MSP 126    AFR 46%    IFR 0.6%    1YR 17    5YR 248    Max Repair 80 MSP
Magazine 104   

GB Magneto-plasma Drive E80 (1)    Power 160    Fuel Use 800%    Signature 56    Armour 0    Exp 15%
Fuel Capacity 100,000 Litres    Range 9.4 billion km   (32 days at full power)
Gamma R300/16 Shields (2)   Total Fuel Cost  32 Litres per day

Size 2 Missile Launcher (6)    Missile Size 2    Rate of Fire 20
Missile Fire Control FC57-R100 (2)     Range 57.6m km    Resolution 100
LOM2 Shuriken (51)  Speed: 20,000 km/s   End: 37.5m    Range: 45m km   WH: 4    Size: 2    TH: 66 / 40 / 20

Active Search Sensor MR2-R1 (1)     GPS 48     Range 2.9m km    Resolution 1
Active Search Sensor MR50-R110 (1)     GPS 8800     Range 50.3m km    Resolution 110
Thermal Sensor TH1-6 (1)     Sensitivity 6     Detect Sig Strength 1000:  6m km
EM Detection Sensor EM1-6 (1)     Sensitivity 6     Detect Sig Strength 1000:  6m km

Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes

The new version:

Skadi IIc class Attack Craft    2,400 tons     257 Crew     485.1 BP      TCS 48  TH 56  EM 150
3333 km/s     Armour 2-15     Shields 5-375     Sensors 6/6/0/0     Damage Control Rating 1     PPV 12
Maint Life 3.4 Years     MSP 126    AFR 46%    IFR 0.6%    1YR 17    5YR 248    Max Repair 80 MSP
Magazine 104   

GB Magneto-plasma Drive E80 (1)    Power 160    Fuel Use 800%    Signature 56    Armour 0    Exp 15%
Fuel Capacity 100,000 Litres    Range 9.4 billion km   (32 days at full power)
Delta R375/20 Shields (2)   Total Fuel Cost  40 Litres per day

Size 2 Missile Launcher (6)    Missile Size 2    Rate of Fire 20
Missile Fire Control FC57-R100 (2)     Range 57.6m km    Resolution 100
LOM2 Shuriken (51)  Speed: 20,000 km/s   End: 37.5m    Range: 45m km   WH: 4    Size: 2    TH: 66 / 40 / 20

Active Search Sensor MR2-R1 (1)     GPS 48     Range 2.9m km    Resolution 1
Active Search Sensor MR50-R110 (1)     GPS 8800     Range 50.3m km    Resolution 110
Thermal Sensor TH1-6 (1)     Sensitivity 6     Detect Sig Strength 1000:  6m km
EM Detection Sensor EM1-6 (1)     Sensitivity 6     Detect Sig Strength 1000:  6m km

Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes

I tried changing the designation back to attack craft from missile boat to see if it would help but no dice. When the new shields became available, I immediately created variants for all of my shield equipped ships to take advantage of the new technology and none of them had any issues.

[se5a]

refitting seems a little odd to me, a bit hit and miss. I've given up trying to figure it out.

[Nathan_]

Stupid option here: close and reopen the various windows.

After that look at the DAC/Rank/Info page and see what the "refit cost from" is for both craft and post that. that might be helpful.

[Jorgen_CAB]

Looking at a glance I see no reason why you can't build these in the same Naval Yard. If the only thing you have changed in between them are the shields you should get a refit cost for 26 BP. And with a total BP of 483 on the old models the new model is way below the 20% that is the maximum in change you can make to build two designs in the same yard.

[metalax]

Refit/building to a different class is only possible if the cost to refit to the different class from the class the shipyard is tooled for, is 20% or less than the build cost of the class the shipyard is tooled for.

Assuming there is no change in tonnage, the refit cost is 125% of the cost of all components that have to be added compared to the old class. There is no credit for components that need to be removed.

[scvn2812 (OP)]

I think that was the issue. The refit could be done but I'd silently sailed past the degree of difference from the original design the yard was tooled for and had to retool. Which was fine, only took a month-ish. If that. The Skadi IIa and b are both perfectly able to be refit at the newly retooled yard into the c variant.