I just got my copy of 'Herd & Mackenzie - The Story of a Shipyard' recently released by Buckie District Fishing Heritage. I think for sure this is 'Nautilus BCK.7 launched by them at Findochty in 1930. She was the only non Steam Drifter built by them at Findochty & described as 'She was fitted with the first semi-diesel engine in the area and was a very successful craft. She was lost during the evacuation of troops from Dunkirk in 1940'. No doubt this excellent local publication will be out of print & much sought after in not too many years.