Launched from the Sunderland yard of J Priestman and Co Ltd. On 18th February 1904 the steel steamship Heimdal measured 239.9′ x 35.4′ x 17.7′ and weighed 1234 gross tons, 761 net tons. She was powered by a triple expansion steam engine by North Eastern Marine Eng’ g Co Ltd. Delivering 147 net horsepower. Her initial owners, J. Johanson and Co of Christiana sold her to D/S A/S Jondal of Bergen in 1913 before she was sold to her final owners B Stolt-Neilsen of Haugesun in 1915. They re-named her Tosto.
On Thursday 14th June 1917 steamship Tosto was loaded with 1870 tons of coal at Methil destined for Haugesund, Norway. The lines were cast off and she headed out to join a small convoy heading for Norway. She was well equipped for the voyage ahead and joined the other ships anchored off the Firth of Forth near May Island. The ships were assembled in two columns flanked by an escort of Royal Navy destroyers. They steamed north and by Saturday 16th the Tosto was anchored off Kirkwall awaiting the next stage of the voyage. That day they raised anchor at set off on the trip across the North Sea with two other ships steaming in single file with Tosto in the rear. The ships were guarded by a single destroyer and two armed trawlers one on either side.
Early the following day, Sunday 17th June, the ships were 3 ½ miles NW of Sacquoy Head when a sudden violent explosion rocked the Tosto tearing her side and she began to sink almost immediately. As the ship settled some of the men managed to launch the starboard lifeboat and four men scrambled aboard. The rest of the crew were forced to jump into the water as she sank. Eight of these men were pulled aboard the lifeboat and a further two were picked up by a boat from one of the trawlers and one last man was rescued by grabbing a lifebuoy and line thrown from another of the trawlers. He was safely pulled aboard minus later. The Tosto then quickly sank beneath the waves as the men watched from the boats less than three minutes later. It was impossible to save anything including the ship’s papers as she sank so quickly. Everything went down with the ship. The men in the lifeboat were safely picked up by one of the trawlers and taken to Kirkwall where they were welcomed and taken care of by the Norwegian consul. Thankfully none of the crew were lost in the sinking.
At the time of the loss it was not known if the Tosto had hit a mine or been torpedoed. The Swedish captain of one of the other ships stated that he had seen a U-boat shortly after the explosion but later records from the German archive indicate that the UC II Type U-boat UC-49 under the command of Kapitanleutnant Karl Patri had laid mine barrage 113 on the 9 June and the Tosto had most likely sank after hitting one of these mines.
The wreck of the Tosto lies in position 59° 16.635’N, 03° 04.826’W oriented 149°/329° in 48 metres rising some 3 metres from the seabed. The wreck is well broken most likely as a result of the explosion damage when she was sunk. There are still major sections visible and the engine and boilers are prominent features. The wreck was identified by the recovery of a bell inscribed ‘Heimdal’ by local divers.