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Forum Index : Windmills : Blade Sizes
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dave r Newbie  Joined: 19/04/2006 Location: AustraliaPosts: 11 |
I am in the process of rewiring an f&p. I hope to put it on my yaght to assist in keeping the batteries charged. My question is - If I use 6 blades (made from PVC pipe)can i keep the diameter down to less than 1 metre and still generate 12 volts, otherwise it is going to be to big to mount over the stern. dave rankin |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Dave It all depends on the wind strength. If you lived in the middle or a cyclone ( well, not the middle. Thats the eye and there's no wind there! Just off from the middle then  ) with 200kmh plus winds, then a prop from a desk fan would give you all the power you need!
Out on the open sea you would have some clean strong wind, so chances are a 1 meter diameter windmill will work for you. You'll get 12 volts easy enough, but watts may be a little down. Some one else here might be able to throw some figures at you regarding what wind speeds would relate to expected watts on a 1 meter diameter prop. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| dave r Newbie Joined: 19/04/2006 Location: AustraliaPosts: 11 |
Thanks Glenn I suppose that I should add that I'm in Perth and we are looking at windspeeds of 10 kph and above. dave rankin |
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| KiwiJohn Guru  Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Dave, is this for use while sailing for to keep the battery alive while she is on the mooring? I think the F&P is much bigger than most wind gennies I see on yachts. I once saw a big cruising yacht, a small schooner actually, that had a generator mounted on the aft railing. They trailed about 50' of fencing wire with a spinner on the end rather like an old Walker Log, they were sailing the Pacific and had been on the go for about a year when I saw it at which time they had only lost one spinner. Such a drive would be pretty good for a F&P but not everyone is happy with trailing something like that. |
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| dave r Newbie Joined: 19/04/2006 Location: AustraliaPosts: 11 |
Hi John My idea was to use it for both. I have a solar panel which produces 4 amps max. If you think that the auto pilot uses 4 amps when the motor operates anbd you have a fridge and all the other things electrical you need something that will supply some power day and night especially if you are offshore somewhere. Regards dave dave rankin |
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Chris Senior Member  Joined: 12/09/2005 Location: AustraliaPosts: 146 |
When your out at sea/offshore, wind would be really good wouldnt it? As in powerful, and pretty consistant. Id just say be carefull, being around salt water all the time will rust stuff very fast obviously  . The last thing you want is a prop blade coming off and hitting something or someone! |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
If he's been about boats for any (non-trivial) time, he'll be well aware of this and be using marine grade stainless and stainless nuts, bolts and washers. (That, or giving things a few good coats of marine varnish to protect and seal them!) |
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| dave r Newbie Joined: 19/04/2006 Location: AustraliaPosts: 11 |
Actually the boat is a steel ketch, 36' long. Chasing the rust is a constant battle. Maybe that's why they call them holes in the water you throw money into, and a lot of your spare time Dave dave rankin |
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