This article is an excerpt from NauticEd’s online Skipper Course, a comprehensive online sailing course for beginner to intermediate sailors to learn how to sail large sailboats 26 ft (8m) and above. Or upgrade to the Skipper Course Bundle to also master maneuvering under power and docking!

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Spinning Propeller

As you sail along, the water flowing over your propeller will cause it to spin. Some sailboats are fitted with a special alternator that will create electricity from a turning propeller shaft.

The energy gained is taken by creating drag force on the propeller blades to make it spin which acts to slow your boat. Albeit minimal.

A propeller shaft generator

With this type of device, sailing at 5-7 knots, it is possible to generate 5 amps or so at 12 volts which equates to 60 watts. In 24 hours of sailing, you could create 1400 watt.hours which is enough to charge 1 small 100 amp.hour (1.2 kilowatt.hr) battery.

You can learn more in the Skipper Course....

Knowledge and theory for longer distances and overnight sailing in diverse conditions. The Skipper Course is a comprehensive sailing course for beginner to intermediate sailors wanting to learn how to sail larger sailboats 26ft to 56ft. Or upgrade to the Skipper Course Bundle to also master maneuvering under power and docking!

Source: Skipper
Topic: Boat Electrical Systems
Authors: Grant Headifen, NauticEd Global Director of Education
NauticEd is a fully recognized education and certification platform for sailing students combining online and on-the-water real instruction (and now VR). NauticEd offers +24 online courses, a free sailor's toolkit that includes 2 free courses, and six ranks of certification – all integrated into NauticEd’s proprietary platform. The USCG and NASBLA recognize NauticEd as having met the established American National Standards.