No idea on the supply request. I am stuck at the second mission on western approach and waiting for some patch or mod to solve an issued with radioman contacts so, basically, I haven't played for a month already.
The deck gun was historically very weak, as opposed to the realistically modded gun of SH3 I find this overpowered. However, after disabling the command deck, your shortest route for sinking a merchant is hitting the waterline.
Historically, torpedoes correctly set for magnetic detonation would cause a catastrophic explosion below the keel. Make sure to set the magnetic detonation 1 or 1,5mt below the keel line. This means you have got to positively identify the exact tgt type and be advised the first torpedoes had problems with the magnetic detonator depending on weather and magnetic areas of the planet. The depth is also a matter of skill as rough sea affects the magnetic detonation as well (the depth is different).
I remember in SH3 we had a waterline mod to simulate the different load of a ship and that heavily affected both the stadimeter AND the correct magnetic depth setting.
In the end, experience does the job. Try and keep trying.
