Cal,
Re "not mess around with all that sailboat racing stuff" and other comments.
There are always other choices. It depends what you want. Maybe you are happy with a fixed prop and the turning noise of an electric motor and drive train when sailing compared to the pure silence of sailing. Personally, if I could (prop in small aperture), I'd fit a two blade folder or 3 feathering for that very reason - and gain a little speed to boot compared to freewheeling a fixed prop or using in regen mode which as we know is negligible on boats around 21ft LWL.
Also back to direct drive. It is to my mind the cheapest, lightest and simplest system for a sail auxiliary in sail boats up to around 8,000lb loaded displacement/21 ft LWL and subject to motor choice will give around 85% of hull speed and a cruise speed in the peak efficiency area of motor operation, subject to prop choice/motor Kt/Kv matching. There is nothing wrong whatsoever with brushed DC and often they beat the brushless systems I see on this list in terms of natural cooling, weight and Kt. I use a bio ethanol stove on board as I would not have a gas (propane) cooker on board, even if I were not using a brushed motor. Others on this list use brushed DC motors similar to mine and 3,000 hours out of a set of brushes seems to me not to be an issue when they are so easily changed.
LiFePO4 for me rocks (25.6V nominal) and certainly for my 24V direct drive system, is safer than lead acid tech, lighter, with a more stable discharge voltage profile, high C rate, fast charging, with longevity and a likely cost per nm the same or less than AGM over time subject to number of times cycled, cycle depth and discharge rates, not to mention greater usable energy and an Ah sizing that can replace lead acid batteries of half their Ah rating. Hence when looking at cost per watt hour stored, one cannot compare Ah for Ah.
Horses for courses...
John
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