prop shaft driven generator

[cadye]

I recently read about a boat that had a shaft/pulley driven generator so it would turn while under sail. Has anyone had experience with this?, any upside/downside to this idea?

[Jeff H]

The down side is that it requires a large area, fixed blade prop that is allowed to freewheel producing a lot of drag and propwalk but not much electricity.

Jeff

[sv_makai]

Prop shaft gen really come into their own in long distance passagemaking. If you are day sailing or weekend sailing from anchorage to anchorage or the dock the 2-8 amps/hr is not much output related to the system expense.

Anchorage to dock and back odds are you are runing your engine to anchor or disembark. This will probably provide as many amps as the prop shaft system.

I would recommend reviewing your power needs and your cruising style to determined if the expense is worth it or if there are other systems best suited to you. Solar,engine driven gen, wind gen, or a large battery bank charged at the dock.

[Talbot]

The trouble with the propshaft gennie is that there is a lot of friction loss due to the gearbox. The prop is not designed to turn the shaft, so again you get losses, In order to connect to a generator to provide some form of power, you will normally need to gear up so that the generator is running faster than the prop - again a loss maker. thus the amount of power generated is minimal, whereas wear on the gearbox, and with a big fixed blade prop, boat speed reduction is a significant disadvantage which could easily be made up with a solar panel. There are two systems that can provide significant power to the downwind sailor (i.e. conditions that the standard wind generator is significantly less effective) these are the Aquagen and the Duogen .

Personally I prefer the more expensive but better Duogen, and a lot of these were used satisfactorily in the last ARC

[Steve Kidson]

I have looked into such devices and have to agree that there are other more efficient and cost effective methods of providing power.

Steve