At 10.00 hours on 1 June 1943, U-178 fired a spread of two torpedoes at convoy CD-20 and heard one detonation but could not observe the results. The Salabangka (Master H.A. Broere) in station #51 was struck by one torpedo on the starboard side in the engine room. The explosion killed ten men and destroyed the starboard lifeboats. The ship lost all electrical power and developed a heavy list to port, so the crew was forced to abandon ship after ten minutes.

At 10.30 hours, HMS Masterful (W 20) which accompanied convoy began to pick up the survivors from two boats and a raft, seven of them injured. The crew of the tug, the master and some men from Salabangka managed to attach a towing line after several attempts failed and around 13.30 hours the tug began to move with the badly damaged ship in tow at 1.5 knots. At about 18.50 hours, a heavy explosion occured on the Salabangka and she sank by the bow in 31°09S/29°13E. Fortunately the towing line parted and the tug was able to reach Durban the same night.