Ernie,
I used the Yorkshireman several times for different tows and scratch-built her using the original Cochrane Shipyard plans to show her in as-built layout. I later passed a packet consisting of GA & Lines drawings plus photographs and publicity material to another Mayhem member who, I believe, passed them again to a third member. Unfortunately, as I cleared out my PM box a while ago, I cannot give you their names. Hopefully, they will see this and come forward.
All I can offer is scans of a United Towing publicity leaflet and a couple of photos but if you PM me your email address then I will gladly send them on. Also, although it is 20-odd years since I built her and my little grey cells are disappearing rapidly, if I can dredge up any info, I will.
Barry M