You can also use it to improve you paddle board hours. No doubt most users of boards are mainly limited by the ability to endure ongoing paddle movement. There is no other gym tool where you can train this aerobic/muscle endurance exercise being as close to the real thing.
Not only does the Air turbine provide resistance, but with the CVT (Continuous Varied Transmission) the swimmer, surfer or paddle board enthusiast can have endless training options. From improve strength in stroke, to power strokes to endurance based training.