Some interesting figures on DC/Hedge-hogs
 

https://www.youtube.com/watch?v=3pi8vZCugRc

1 in 60 DC attacks resulted in a sunk U-boat, 1 in 6 Hedgehog attacks. 3 minute reloads for hedge-hogs. 7 seconds for a hedge-hog round drop to 200 feet (61m) [so 21 seconds to 185m? assuming a terminal velocity reached inside 7 seconds?]

It seems to me that we need to make the DC's considerably less lethal than they are currently, but increase the number of DC attacks/search for lost contact v u-boats, and allow for hedgehog attacks 1942 onwards.

This would achieve two good results. It would make the most dramatic and anxiety induced content - namely having to endure and evade DC attacks whilst progressively accumulating damage, with a fairly low risk of an outright destruction, and, in mid-war games and onwards, a much higher chance of destruction of the uboat if it is detected shallower than circa 90m. It would also allow, if the sonar/hydrophone cones of detection were less simplistic, (ie the two were complimentary rather than the same in shape of detection) for u-boats to still be hit at 185 via hedge-hogs, BUT, with still-giving the u-boat a sporting chance of evading the hedgehogs with a 21 second interval between splashes and possible hit....