Hull number 70 was laid down at the yard of John Lewis and Sons, Aberdeen by the Shipping Controller in London during the latter months of World War One but, with the conclusion of the war, the ownership of the unnamed hull was acquired by the Mason Shipping Co Ltd., Liverpool. Launched on 10th September 1919 the steel steamship was named Tarnwater which measured 164.8′ x 27.0′ x 11.1′ and her tonnage was 575 gross tons, 262 net tons. She was powered by a triple expansion steam engine by John Lewis delivering 105 nominal horse power. In 1927 management of the vessel was taken over by James Fisher of Barrow-in-Furness and his company, James Fisher and Co Ltd acquired the vessel on 28th December 1933 and renamed her Bay Fisher. The vessels official number was 143599.
With the outbreak of Word War the Bay Fisher was employed on war time duties predominantly servicing the larger ships heading west to America. She took part in nine various convoys between the Clyde, Oban, Methil and down the east coast of England as far as Southend. On 4th February 1941 she left the Clyde in convoy WN.80 along with sixteen other ships and five escort vessels heading for Rosyth via Scapa Flow carrying government stores under the command of her skipper, John Todd with a crew of eleven men. When on the 7th February, in a position three and a half miles north east of Bell Rock the convoy was attacked by German bombers with the Bay Fisher suffering a direct hit. Eight of her twelve crew, including the skipper, were killed in the impact leaving only four survivors.
The main body of the wreck of the Bay Fisher lies in position 56° 28.167’N, 002° 19.296’W oriented 070°/260° in a depth of 48 metres and rises 7 metres from the gently sloping seabed. A debris field spreads out some way from the main wreckage which is recognisable but well broken, the new Navionics and C-MAP Reveal charts clearly show wreckage 200 metres NE of the main body of the wreck. The wreck was positively identified in 2001 by the recovery of her bell inscribed Tarnwater.