Graeme wrote:

I can't find anything on the boat David refers to but I recall it too, up North, it had a large horizontal axis wind turbine, mechanically driving the propeller. It could sail directly to windward. Since then there have been others and there are examples of prototypes which you can find by googling "rotary sail boat".

The example in this photo looks to be a wind generator driving the propeller through an electrical transmission.

(Rotary sail - not to be confused with "rotor sail" which is a vertical axis rotor presented to the wind, proposed for cargo ships, which make use of the "Magnus effect". In this case the rotor is not wind driven).

Ugly!! Now we are getting to far away from the simplicity of the junk rig, Ha ha.

I was browsing on the Class Globe 5.80 Facebook site this morning. I was thinking of building one of these little boats for a while but decided they are going to be very expensive for the amount of boat, I think the junk rig Wave Rover 650 will cost a lot less and be a better boat for the money. But I like to follow what is happening with the 5.80 because their first trans-ocean race is to start soon. Anyway the point of this is that apparently the class 5.80 rules require e propulsion in an outboard so we might see some interesting development with electric outboards and associated hydro charging in this small ocean racing class of yacht. Although this is more for the electric outboard thread.

Howard wrote:

David:

      Sailboats  spend what?  90%? of their life at anchor, on a mooring, or in a slip. That makes a wind charge a better choice over all as a backup for solar power as compared to a hydro generator.    It means having only two rather than 3 systems.  I don't share your fondness for them.   Under weigh, in theory at least a  hydro should be more efficient and more powerful, and far less obnoxious, and equally useless in no wind conditions, but you would have to anchor in a  pretty strong current to use one anchor  ;-)

      Anybody figure out how to use a wind charger as a driving sail?    It's up there catching wind, but except on a run providing no useful driving force.....

                                                              H.W.

Very true that most yachts spend 90% plus at anchor, or generally not being used. I think for a long term cruising yacht which does not want to rely on fossil fuel for providing energy needs then in order of preference: solar, hydrogenator, wind generator. Solar is great being passive, all that is needed is sufficient effective surface area of panels, and the electrical needs of the boat geared towards the available supply of solar generation. 

Hydrogeneration would come next in preference while a boat is underway, preferable a transom mounted, or propeller shaft type unit over a towed propeller. Unfortunately any of the commercially produced units are very expensive, so this is an area where it would be great to see some DIY solutions. Wind generator comes last, but once set up can be an effective solution alongside and complementing solar panels. My preference here is for the multiblade units which seem to have been perfected in the Rutland brand wind generators being an effective trickle charger, not too obtrusive, and not too expensive.

I do recall some decades ago that in New Zealand there was a yacht propelled by a very large wind generator, or 3 bladed large diameter air propeller mounted on a mast, and driving through a series of gears and shafts to an underwater propeller. It seems to have disappeared from use and there has not been another one, so maybe not a success.  

Howard wrote:

small wind chargers are unpleasantly noisy from what I've seen... If it isn't blade noise, it's bearing noise, or the whine of the generator itself generating.  

      On a boat, solar, hydro, and wind all have a place.   However under weigh it seems silly to use a wind charger..... at anchor is where they seem best suited. 

                                                       H.W.

I disagree about the noise. After the good cleanout of the internals that Chinese made wind generator was not really that noisy. I am a person who does not like distracting noises when I am trying to read/sleep/converse/listen to music/listen to nothing when I am sailing. The noise produced by the wind generator was more a very quiet rumble   that made you aware that it was whirring away somewhere down the back of the boat. Most of the sound was transferred through the mounting pole. But, yes it was internals rather than the blades spinning through the air. That was a 5 blade unit with an overall blade diameter of about 1100mm. If it ever got annoying I would just stop it which was easy to do, but I never did that very often. The real Rutland unit which had six blades of about the same diameter was almost silent so you just had a sense that it was operating. Even sitting directly below the unit there was only a very muted sound of the blades spinning, but no real noise from the internals. Maybe that is what the extra $1600 bought - more refined engineering. It seems to be the large diameter 3 blade units that produce the most noise, which is more the sound of the blades cutting through the air. In one marina I was parked next door to a yacht which had an Air X or similar 3 blade unit. That was noisy, sounded like a helicopter operating next door. After a couple of days listening to that unit I decided my Chinese made unit was actually very quiet!

I also disagree about a wind generator not being useful while underway. On 'Footprints' the wind generator made a very real contribution to our battery charging needs during ocean crossings and even long coastal passages. This was on a yacht which relied on solar and the wind generator for battery charging, we did not have an inboard engine with a high output alternator. While on an ocean crossing the solar panels and wind generator powered all the necessary internal lights, LED nav lights at night time, a 35 liter capacity electric fridge running full time, use of an SSB radio each evening, and charging via an inverter each day of various devices. As stated previously in this thread even after a day of not much sun and during hours of darkness our batteries were always fully charged and often during the night sitting over 13 volts. I had an ammeter connected to the wind generator and it consistently put out between 1 to 3 amps depending on how much apparent wind there was and even that relatively low output adds up over a 24 hour period. I was always glad that I had fitted the wind generator which proved a valuable addition to our battery charging needs both under way and at anchor. 

The above notes are not opinions but observations based on real experience in the very real world of coastal and offshore sailing.

Thanks David. I fixed it.

AGraeme wrote:

Thanks David.

Interestingy, I compared the power curves of a 500 watt Rutland Horizontal Axis with a rather crude and agricultural-looking 500 watt VAWT - both have about the sale swept area, and they are comparable at their maximum outputs (which both occur at around 25-30 knots.

The difference is in the

                         5 knot    10 knot    15 knot    20 knot situations

Rutland VAWT     10W      40W        130W        280W

noname HAWT      0         25W        125W        310W

If the graphs are correct, the more expensive Rutland is better in the 5-10 knot range. In higher wnds the VAWT earns its keep, and may be quieter, I don't know, I think its RPMs are less.

Comparable, I think.

I forgot to mention 2 things about my slightly noisey Chinese made wind generator. The first is that after researching about this issue I found out that the reccomendation is to dismantle the unit and give the internals a good clean, which I did and it certainly seemed quieter after that attention. The second is the bit of noise it made was not so bad, and it had the advantage that the wind generator became a kind of wind speed indicator. During our ocean crossings when I was off watch down below the amount of noise the wind generator was making was an excellent indicator as to whether we had too much sail up and it was time to reef, that was when the wind generator produced a real scream. Or if we were reefed down and the sound of the wind generator diminished, then it was time for more sail!

If one purchases one of the recognised known brands of wind generators then many thousands of dollars can be spent. But if one is prepared to accept a bit of risk then importing a Chinese made unit can be a much lower cost alternative. The very expensive recognised brands could well have been made in China anyway, maybe in the same factory. You know the story, designed in California, but in the small print on the back of any Apple product - Made in China. The majority of solar panels that find their way to NZ seem to be made in China and even the fairly inexpensive solar panels seem Ok.