Pete,
Sorry to here about you having your jacket pinched. I can only sympathise as i know what is like as they got away with a bigger haul from my boat a few weeks back, but to do it in broad daylight they have the nerve and know the lay of the land.
The only place I feel safe is at anchor amongst the islands as it seem once theives have been onboard you think they may come back again and again. I only hope they get caught get what they deserve as they may board a boat when the owner is onboard a god knows what may happen.