Dito, however when my african seach proved fruitless, I sailed in to freetown (1941) and sunk a docked Liner, a couple of tankers and some small merchants, then I hit a sub net which forced my bow to break the surface and I got mauled by some armed merchies an a DD (which soon after commited suicide by ploughing in to the pier at 18 knots after it attempted to follow me in to the harbour- BOOM!!!
)
Good thing about harbour raiding is that you can get some good underkeel shots
if the torpeedo fails to detonate under the ship it can hit the harbour wall next to ship and still cause as much damage. or bounce then hit the shallow ocean floor under ship - same effect... so long as it not a dud, you cant miss!