Built towards the end of World War One the steel steam trawler James Christopher served briefly for the Admiralty in the last few months of the conflict before being purchased by Skomer Steamship Company of Cardiff after the war ended.
Five years later she was purchased by Brand and Curzon of Milford before changing owners one more time to J Marr and Son of Fleetwood where she was allocated the registration number of FD21 and renamed Marsona in 1929. She measured 125.3′ x 23.4′ x 12.6′ and weighed 276 gross tons, 109 net tons. Her triple expansion steam engine by J P Rennoldson delivered 61 net horsepower.
At the outbreak of the Second World War she was again requisitioned by the Admiralty as a minesweeper based in Cromarty keeping the entrance to the important naval base free from mines laid there by the German U-boats and aircraft. On the 4th August 1940 the Marsona set out on her usual minesweeping duties under the command of A W Ellis RNR. It is not entirely clear what happened that day as the skipper and all his crew of eleven men were to lose their lives when the Marsona was lost in an explosion less than three miles from the defensive boom for the Cromarty Firth.
The subsequent naval enquiry focussed on the complex channel in and out of Cromarty that provided strong defence against enemy penetration of the base. There were two ninety degrees turns between the inner base and the open sea but this configuration resulted in an exceedingly difficult manoeuvre for a minesweeper exiting the base and deploying their sweep in a manner that avoided the buoys and nets marking the channel but provided the minesweeper itself with some protection against any mines in its path. As far as the Marsona was concerned, almost as she reached the open water, two huge explosions tore the trawler apart killing all her crew. Although German archive records don’t clearly attrubute any mines in the area to a specific U-boat the subsequent enquiry surmised that the Marsona had caught one mine in her sweep and simultaneously collided with a second mine. Only five bodies of the crew were recovered. Although the members of the enquiry were divided in their opinion on the pros and cons of the channel layout and whether the Marsona should have navigated the channel safely the channel was simplified shortly after the incident by removing the two ninety degree turns.
The shattered wreckage of the Marsona lies in the channel into the Cromarty Firth where the explosion sank her. The wreckage lies in two major pieces with the position 57° 40.432’N, 03° 55.117’W marking the northernmost section. The second piece lies close by in position 57° 40.399’N, 03° 55.068’W. Both positions show scattered wreckage lying in 16 metres rising one or two metres from the seabed.