minor bug
 

On the shallow depth gauge there's a correction for atmospheric pressure to the displayed depth on the 25m gauge. There's a plus sign and negative sign, but they're on the wrong side. The higher the atmospheric pressure the more depth you have to subtract to get a true reading?

As the internal pressure increases (due to things like venting the negative and regulating tanks into the boat, firing torpedoes etc), the indicated depth is then too low, as the gauge is measuring this differential (external water pressure vs pressure in the pressure hull). Bootskunde (the high-level overview document of boat systems issued to every boat) recommended constantly validating the shallow depth gauge reading against that of the Papenberg due to this.

Thanks for clarification.