At 07.35 hours on 23 Feb 1943, U-186 fired a spread of three torpedoes at convoy ON-166 about 310 miles south of Cape Race and observed one hit after 2 minutes 32 seconds on the ship in station #12, the Hastings, which was erroneously reported as Hassop. A second hit, after 2 minutes 35 seconds was possibly on the same ship, which sank within seven minutes. After 2 minutes 41 seconds a third hit was heard but not observed.

At 07.40 hours, U-186 fired a spread of two stern torpedoes and heard two detonations on different targets, but only the Eulima was hit, the second detonation being a depth charge from the US Coast Guard cutter USS Spencer.

At 11.30 hours, the drifting wreck of the Eulima was sunk by a coup de grâce and gunfire from U-186.

A lookout on the Hastings (Master Richard O. West) spotted a torpedo just before it struck the port side at #5 hold. The explosion flooded the engine room, sprung bulkheads between the #4 and #5 holds, destroyed the steering gear and cut the power of the ship. The ten officers, 31 crew members, 20 armed guards (the ship was armed with one 4in, two .30cal and four 20mm guns) and one passenger on board began to abandon ship in three lifeboats and two rafts. The ship sank stern first after 7 minutes. One officer and eight crewmen were lost. The remaining survivors were picked up after 20 minutes by HMCS Chilliwack (K 131) and landed at St. Johns.