Just received info that the US ship might have been the USS Simon Lake and not the USS Hunley. Seemingly the Simon Lake took over from the USS Hunley at the Holy Loch Scotland around this time. So maybe the tugboat was helping guide it out of the Holy Loch or into the Holy Loch. If this is correct then it may have been around Jan 1966 looking at the latest dates that this happened. Well at least I might find out more now. But still, when I search the web with the new info there is nothing.