Yeah, ingame the SJ1 cuts out around 40 feet, but the main irritation I was trying to cure is when on accelerated time in rough seas it keeps cutting out and the idiot operator never automatically turns it back on.
So far this doesn't do everything I thought it would - changing the surfaced draft to 14-15 feet doesn't affect rough seas causing it to average 20-24 feet. In any case I'm pretty sure the submergence depth only affects the diesel cutoff and shift to battery, nothing else. Increasing submerged draft helps with that for decks awash, but again increase it too much and I get really bizarre problems with trying to dive. The whole point of a submarine is the ability to submerge, so any hack that screws that up is not good.
Still haven't had big enough waves in this patrol to see whether the radar cutting out is affected or not.