SirHendrik - bloody brilliant mate- thanks for giving us a headsup!
OK - I think maybe I have a clue here. Granted - it depends on what your aiming a mod to do - but since we have 2 different damage models here - one hull and one internal - I think I see how to change things. This is all conjecture though I will be trying it when I finish writing if time allows. Since in the UPC file of each sub there is a list of the compartments with a HP value for each - usually 200 - but not a HP value for each piece of equipment - it looks like damage in a compartment is applied on a curve or sliding scale. The bulkhead getting the brunt (simulating hull damage causing leaks) with the rest being applied semirandomly to the rest of the "equipment" in the room. If that is the case - then if you want to reduce the "static" or external and unrepairable damage without changing how the internal model works - you would just adjust the Hp for the entire sub. Since this would - apparently - only affect the crush depth and pressure damage coefficients - they could be tweaked to still give realisitic results.
On the flip side - if you wanted to modify the dynamic or internal damage - you would change the COMPARTMENT HP value without changing the overall sub strength.
Basically - it boils down to 2 models and a different set of variables controlling each. Hopefully changing whichever set involved will allow the results one wants.
In SH3 a compartment destroyed was equal to a destroyed sub. With the dual damage model - you can in theory lose 2 compartments ON THE surface and still have a chance at survival - but if you loose ONE submerged you are also losing 1/3 of your total hull/ bouyancy strength - putting you REALLY close to going down no matter what - since at a loss of 50% you death spiral. And since you can "repair" the room - but not the associated hull damage - we see why "healthy" subs still have severe angles and control problems. In reality - this could also explain the "BUG" some people saw early when they would get damaged - fix things - and then dive without an ability to recover - if the damage sustained and then repaired was over half the hp value of the sub.
In the end = this is going to take some work balancing the internal compartment HP values, the "whole sub" values, the pressure/damage variables, as well as the damage amounts for all the weapons in the game to get things where you may want it. Unless someone can find, or one of the devs can point us to, a variable that affects how damage carries over from external to internal. Right now - it looks to have a 1:1 ratio or higher (internal damage equal to or higher than what is applied externally). That would be a godsend if we could play with it. But I doubt thats something we could get to.
On a side note - it was earlier posted that someone thought they knew where the "Armor" variable that is actually used went (as the ones in zones seems not to be used any longer) - anyone want to share????
Note - in case you havent noticed - I ramble when I brainstorm
Good Hunting
Captain Haplo