It would work ok in areas with little to no currents such as bays and protected sides of islands. It's definitely a scuba
use unit and the 'efficiency' depends solely on the operator's fitness level IMO.
Still wished we had met (Dave/Exit Only) when I worked down there I could've taken you for a submarine ride....Guess I was too intimadated by the totally rigged out for cruising Exit Only when I spied her from the Causeway Bridge, and figured you were just another cruiser heading somewhere. Had I only known!