thanks Mikhayl, found it here :
http://www.subsim.com/radioroom/show...=136244&page=2
so I modified the NSS_Kaichu.upcge :
[...]
[UserPlayerUnit 1.Compartment 4.Bunker 1] ; Forward Torpedo Room
ID=BowTorpedoRoom
Capacity=
10 [...]
not 2 anymore, now we can play

will upload the new version tonight, and also just the modified file.
I also moved the aa gun aft and put a 105 mm gun upfront.
K