Originally Posted by K-61

My Kaleun is in patrol 6 in Nov. 43. Transiting the Bay of Biscay results in having to dive several times, though for some strange reason I was not jumped once on my return voyage and I use max 256 TC for the trip. The most important upgrade you can make in my opinion is the radar detector and then the schnorkel, although it has not been offered to me yet. I generally stay under for at least half an hour before surfacing again, but usually an hour or more. To maximize my ability to remain under I always upgrade to the latest batteries and only proceed at slow ahead. It's air that limits my time underwarter most of the time. The escorts are now both more numerous and skilled. The last convoy I attacked had nine escorts, but I still managed to sink two large merchants from it. After that I broke off contact as the weather was filthy and I did not wish to risk another surfaced approach, knowing they had radar. And, oddly, I have not yet encountered a Hedgehog, but I'm sure my time will come.

Patience and discretion are the words of the day. Overaggression will get you killed in no time. Keep a fresh and competent bridge watch at all times and a qualified sonarman in hydrophone room.