I believe that his normal mooring technique with hired yachts is to wrap the dinghy's painter round the prop; hence knackering all motive power. The preferred solution is then to tie the dinghy alonside with what remains of the painter, and attempt to shift the yacht using a small outboard.
So, you should have been on the look out for an apparently out of control raggie craft, emitting a stream of expletives in a Yorkshire accent.
i'm in lax lounge enroute back from Bora-Bora/Tahiti. BVI and indeed whole caribbean is getting a bit full of arc-yotties and other boat tourists doncha know...