Yes Jane - I tried those wrist bands several years ago and they sort of worked. Maybe I should get another pair.   I've also heard of those electrical ones although they seem expensive.

Well, my Day Skipper(Power) course at Easter has been cancelled coz the boats' engines are sitting in a workshop at the moment, so I'll have to wait till my next sailing trip on the Clyde at Whitsun to test out these ideas.

Many thanks to all.

Steve