Thank you all for your replies. Yes, Ballast, I do mean the green ballons which should show up when the towing menu is opened, not the navigation lights! It is frustrating that, having got this far in the mission, I cannot now connect the tow-line between tug and Vermass. I may try sailing her to her new moorings without the tug. I wonder if that will work? Tug will probably have to go as well, but unconnected.
Many thanks
Paul