Yes, quite so.
I'm in a S-boat also. No radar, no AA and best of all, the RFB corp. shipyard decided to use paper-mache for my hull, instead of the "old- fashioned" steel.
I've been lucky on this patrol though. Only bombed twice in 3 weeks.
Part of the problem may be my crew not spotting the AC soon enough. On more than one occasion, when I checked the perisccpe, the AC seemed pretty close. Now, if in doubt, I go deep.