How do Moorhens swim so well without webbed feet?

On our lake we have a lot of Moorhens. These birds swim as well as ducks – I’ve even seen them beat ducks in a race for food – but they have no webbing at all on their feet. So how do they swim so well? And being that they do swim so well without webbed feet, then webbed feet obviously are not necessary to be a good swimmer; so do webbed feet serve some other function besides helping to swim?