Well, I got tired of the dance and decided to put my boat at the bottom. I fully expected to get destroyed but strangely enough so far I had only one hit causing only minor flooding which my crew soon repaired. It seems one destroyer is now out of depth charges and the other only throws some ever hour and a half or so. But they keep pinging me and circling my position.
I have been on the bottom for hours now (compressed time x32) and decided to wait 'till dark, preserving battery power. Oxygen should last another good couple of hours. I hope to maybe sneak away on the surface in the dark, maybe I can get some hits with my deck gun in the process.