I am using RUB 1.45 - it's the only mod I am using in fact, and my experiences seem rather different from yours. Maybe its another Mod which is causing problems with RUB.

Attacked a convoy last night ENE Scottish West coast in very bad weather. Due to weather conditions, was very reliant on sound contacts (visibility about 2000m) and managed to identify maybe 2 DD and about 12 Merchants. Was able to slip into convoy on surface, crippled a C2 with 2 torpedos (marked it's position on map as i passed as visibility so bad), race past it, fire third forward torped into a tanker (hoping to disable it but it actually exploded on torpedo impact) and then dive.
While dived, circled back towards crippled C2 using hydrophones to follow progress of DD which was now hunting me, switching to silent running whenever he lokoed to be approaching. Managed to evade DD and put last forward torpedo into crippled C2, sending her to bottom. Surfaced, turned my tail towards DD (which was about 2500m away at edge of my visibility) and made flank speed away - again without being detected.

Am playing at 84% realism (like the external view for those 'Das Boot' dive and surface shots :) ). Had been attacked by aircraft (NW of Aberdeen) while making way to patrol grid, but dived and as soon as it was spotted and it dropped its depthcharges somewhere aft of my position, judging by the sound.

So I am finding RUB quite a good mod, myself. I hope though you manage to resolve the issues you are having with it :) Sorry can't offer anything more technical, just showing that maybe it's not RUB thats the mod causing problems...


edited to say that had forgotten to put dates of above battle - is a new campaign, that attack took place Dec 1939.