At 13.26 hours on 5 August 1942 U-155 surfaced astern of the unescorted and unarmed Draco (Master Daniel Lucas Stevenson) about 420 miles east of Tobago and fired several warning shots from the deck gun. The crew immediately stopped the engines and abandoned ship in two lifeboats with eight men in each without sending a distress signal. While the port boat in charge of the chief officer quickly moved away, the starboard boat in charge of the master stood by the ship until rounds fell very close because the U-boat began to shell the ship from the starboard side, starting heavy fires. The Germans ceased fire to question the survivors, asking the usual questions about name and nationality of the vessel, port of departure, destination and cargo. As the Draco did not sink, the U-boat then continued to shell her from the port side and fired approximately 35 rounds in total. The ship began to list heavily after a boiler explosion, eventually capsizing and sinking slowly by the stern at 15.30 hours.

Both lifeboats set sail in good weather towards the coast of South America, staying together for the first two days but then proceeding independently as both were equipped with sextants. Several rather low flying aircraft were spotted during the following days, but the boats were not seen despite their red sails and firing smoke rockets. The chief officer and seven survivors were picked up by the British motor tanker Athelbrae on 12 August and landed in New Amsterdam. The other boat made landfall at the mouth of the river Nickerie in Suriname on 13 August. The master was of the opinion that the loss of his ship could have been avoided if the naval authorities in Rio would not order small vessels to follow ocean routes. He had urged the US commander for a coastwise route like the one given to them on their southerly voyage but could not persuade him.