West Mersea Duck Punt, which he expects to be megafun for racing about the mudflats and he may be right and all. They are long (15ft), thin, flat bottomed and totally without fripperies like centreboards or rudders. This means they have to be steered by an oar, which usually has to be brought into vigorous action when going about.
West Mersea Town Regatta last year, and I expect they go reasonably fast.
When racing, the sailors seem to be able to row them facing forwards, which must be less than totally efficient but needs must if the wind dies, I suppose.
But it prompts a thought. What about racing duck punts over a course with an upwind leg where rowing was compulsory?
The boat would probably have to be a little beamier to allow the rowsailor to turn round on the thwart when changing from muscle to wind power. Or it could be run by a crew of two, one to row and steer and the other to tend to the sail. Perhaps a more traditional duck punt design such as Selway Fisher's Ruddy Duck Punt would be better, and its decks would make it less easy to swamp too.
PS - The main race at West Mersea regatta has to be rowed with two people and two oars, so most competitors row as a pair. It looks like tremendous fun. This year's regatta is on July 31.