[www.vwoa.org]

In the above link, JAMES A. JOLLY PhD, Professor Emeritus, California State University, Sacramento details his time aboard the Edmond J Moran (sea going tug) as a radio officer. He details what is probably this "sinking". The uboat was diving and part of the conning tower hit the hull of the tug. Navy escort ships dropped depth charges, there was a release of oil and the uboat was reported sunk. It is implied that this was 1942 in the "Windward" passage (in the Florida keys?).