At Strictly Sail Miami last February, the Moorings 4300 Electric, built by Robertson and Caine, made its boat-show debut. (It had already been operating in the B.V.I. charter fleet for several months.) The model came into existence not because the builder had planned to introduce such an iteration but because its owner, Anthony West, decided he wanted a Moorings 4300. What's more, he wanted a Moorings 4300 with a diesel/electric drive.