> Two rowing machines could provide roughly 400 watts of power. If they are operated around the clock in shifts, they could supply the ship with an extra 9.6 kW

> Two rowing machines could provide roughly 400 watts of power. If they are operated around the clock in shifts, they could supply the ship with an extra 9.6 kWh of energy per day Rowing 200 watts is not exactly easy. That's like 2:00/- splits, "ramming speed" type power. Half that seems more reasonable. I do like the idea, though, of a sailing ship with ad hoc erg/rowing power.