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Old 03-04-2015, 09:10   #46
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Re: Silentwind Wind Generator

I hv a friend with whom i regularly sail who recently fitted a Silentwind 400, transom mounted, with MPPT wind+solar regulator. I agree it produces good current but our installation would hum a bit above about 20Kn. Not so noticeable in the cockpit but just too much for anyone in the aft cabin so we wld switch ON the lock overnight. There was an auto-brake at about 29Kn. I note that Calder (2009 Edition) speaks very highly of the Airbreeze ("Without question the most sophisticated wind generator currently available on the market"). Now that the technology has made it possible, surely it is essential to use an MPPT regulator to get the best out of a windgen or from solar?
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Old 03-04-2015, 09:47   #47
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Re: Silentwind Wind Generator

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I hv a friend with whom i regularly sail who recently fitted a Silentwind 400, transom mounted, with MPPT wind+solar regulator. I agree it produces good current but our installation would hum a bit above about 20Kn. Not so noticeable in the cockpit but just too much for anyone in the aft cabin so we wld switch ON the lock overnight. There was an auto-brake at about 29Kn. I note that Calder (2009 Edition) speaks very highly of the Airbreeze ("Without question the most sophisticated wind generator currently available on the market"). Now that the technology has made it possible, surely it is essential to use an MPPT regulator to get the best out of a windgen or from solar?
That's funny... mine actually gets quieter the faster the wind.

I think the 29 knot shut off had more to do with the programming of the regulator (which I do not think is mppt BTW) than the wind generator as it has set points for various values to tell it when t turn off.

IMO - A lot of the "quietness" or "loudness" of a wind generator has more to do with the individual installation than the actual generator. For example, installation of an anti-vibration pad and sound baffling material in the tubing...

We have a silentwind and regularly use our pilot berth when the boat gets bouncy at anchor and have not had a problem with noise. That said, our friend had a D400 and its a lot quieter.
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Old 03-04-2015, 10:03   #48
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Re: Silentwind Wind Generator

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That's funny... mine actually gets quieter the faster the wind.
Same with ours.
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Old 03-04-2015, 12:11   #49
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Re: Silentwind Wind Generator

I think you cld be right about the installation. My friend's SilentWind 400 is mounted on a SS post which used to be a small crane for the outboard but he sensibly changed the o/b for a smaller one and then converted the crane into a post for the wind generator. I suspected the incorrect mounting of the vibration pad just underneath the generator and i know for sure that the post has no added baffling in the tubing. It could also have been helped if the foot of the post had a rubber pad between the post and the deck.

It does not make any more than a quiet swishing noise in the cockpit but the hum down below is at about the frequency of Middle "C".

You are right about the brake at a given wind speed. I left it at the supplied setting which was about 29Kn. The brake then applies automatically for about 3 mins and it then starts up again. Think it is simply a matter of how much heat develops in the regulator and this setting can be changed.
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Old 03-04-2015, 13:08   #50
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Re: Silentwind Wind Generator

The brake is not just for protecting the regulator from overheating, it do also protect the wind generator itself. If the wind speed doubles then will the power increase eight times, and that will not the windings in the generator stand.
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Old 03-04-2015, 13:15   #51
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Re: Silentwind Wind Generator

The Silentwind doesn't need to be braked until about 60 knots. You will fill your batteries well before that is ever reached, so by then you are in brake mode anyhow. In which case, you simply flip the brake switch to keep it permanently braked.
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Old 03-04-2015, 13:33   #52
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Re: Silentwind Wind Generator

A quick calculation says that there is something that’s wrong. If I remember right do the specification for Silent Wind say that it will give 400 W @ 26 knots. 60 knots is more than the double and then should the generator have given 3200 W, and that is unrealistic. It’s needed to be braked long before that.
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Old 03-04-2015, 14:33   #53
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Re: Silentwind Wind Generator

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The brake is not just for protecting the regulator from overheating, it do also protect the wind generator itself. If the wind speed doubles then will the power increase eight times, and that will not the windings in the generator stand.
Lars, how are you figuring the math on the power increase vs. wind speed things? I ask as with everything else in terms of the wind, when you double the wind, it's force goes up 4-fold. It's a squared equation.

--> Guys, my apologies for the long "science lesson", but. There are a couple of key things which I think are missing in (some or many) peoples "experiences" with power generation vs. wind speeds.
~ In particular, very few boats have reliable, calibrated wind instruments 10' off of the deck. They have'em up at the mast head, where;

A) They're in clear air (kind of like when & where some manufacturers will "test" their generator's output).

B) It's a know fact that even just 40' or so above the water's surface the wind speed is a minimum of 15% stronger. Keep in mind the squared function thing, & how huge that is at low (especially single digit) speeds.

C) Most marine wind generators I see, are mounted at say, 15' above sea level. And are dead in the wake of the trashiest air onboard. Generated by everything from:
Masts & rigging, furled sails (vertical & that one on the boom), utterly debaucherous turbulence from dodgers, cockpit weather cloths, half open deck hatches, & awnings. As well as RIBs with outboards, hung from davits 5'-7' right under the generators. And solar panel fields (in the wake of the Bimini), right above the dinghy.

- In racing circles, it's commonly known that the wind shadow from another boat is a minimum of 15X+ their rig/sail height.
- Their crews wear skin tight clothing & sit hunched together, aerodynamically on the rail.
- And the same crowd would have 15' tall (vertically) wind instrument wands, projecting out beyond the bow in efforts to get accurate wind readings, if such were feasible.
As even just a bare mast & rigging produce way more than enough updraft, & (at best) semi-predictable oscillating, angular vortices, which (at times) maim their wind instrument accuracy.

So the bit about dodgers, & everything else on deck, plus the rigging, etc. fouling the air is not hyperbole. And I can give you an easy, albeit messy, visible test to see said effects if you like.

Thus in light air, say 10kts (masthead measured), the wind generator is lucky to see the realistic equivalent of 5kts, or a touch more. AKA 1/4 of the masthead measurement, given the square of velocity thing.

It's something to keep in mind, when figuring out where to mount a wind generator & other accessories. Plus, my Redwing, aside from making heaps of power, is fairly quiet up in the fore triangle.... Until it's time to tuck it away (while it's still easy to), unless you had zero juice.
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Old 03-04-2015, 15:08   #54
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Re: Silentwind Wind Generator

Er, Er....there are quite a few App downloadable for IOS or Android which can turn a smartphone into a hand held Sound Meter or Sound Level Meter.
Some come for free "Decibel 10th" or at a cost SoundMeter for Iphone ($19,99).


It would be nice to have figures in front of "fairly quiet" or "reasonably silent" .
;-)


That said, I have no idea about what kind of accuracy can be expected from said Apps.
We would have to agree about a way of measuring...
Distance (set) @X wind speed (top of the mast) =n Db
In order to get a repetability of measurement.
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Old 03-04-2015, 15:12   #55
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Re: Silentwind Wind Generator

Uncivilized, with all the facts you give I think now one will mount a wind generator, but I think It’s right. Often I have the wind from the side, and then many of the disturbances will not occur. If I remember right, (there's nothing that says I do), should the power increase with the wind speed in cubic. If I look at the power diagram for my wind generator do that fit with an increase in cubic. But this doesn’t take out the content of what I say, that the power figure is unrealistic.

Its to late on the day for me to check it, but I think the wind should be measured at 10 meters height, and it shall be a 10 minutes average. But even so, there is no boot that measures it that way.
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Old 03-04-2015, 17:16   #56
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Re: Silentwind Wind Generator

You can configure a decent number of sailing instrument packages to measure wind over time & keep a log of it, just like a barograph (some of them have those too). In fact, measuring wind that way is critical to boat performance (speed), as well as tactics - if you're into either. Plus being a big tool in predicting weather.

And you can also get sensors to mount in other places in addition to the masthead. Such extra bits of kit for a fancy instrument package help in dialing out (via software) the effects of sails, rigging, etc. on getting truly accurate measurements of the wind. ~ If you start to look closely at pics of some of the RTW racers, you'll sometimes see them on antenna masts aft & such. And occasionally on the backstays (of racers that still have them).

Here's an example of an "extended" masthead wind sensor http://www.nke-marine-electronics.co.../carbowind-hr/ I say Extended in quotes, as it varies by racing class/rules, how long your wand can be. In the '92 & '95 America's Cup, some of them just got stupid long. Like several meters. 'Course that race brings folks to do all kinds of loony crap, for the extra 0.001kt, literally.

For independent monitoring (non-boat mounted instruments) have a look at a few Kestrels Kestrel Meters - Handheld Weather and Wind Meters - KestrelMeters.com Nominally, they're "hand held", but... Some even have blue tooth links, so that you can temporarily mount the unit wherever you like, & it downloads all the real time atmospheric data you could ask for to various type of computers or smart phones.


Back to the loony ideas theme. I'm surprised that no one's mentioned mounting localized, focused, active noise cancellation units on/aimed at their wind generators. I'm sure we'll see it at some point. I mean they've been putting them into cars & other vehicles for 40+ years. Probably most notably the Dodge Viper IIRC.
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Old 03-04-2015, 18:58   #57
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Re: Silentwind Wind Generator

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A quick calculation says that there is something that’s wrong. If I remember right do the specification for Silent Wind say that it will give 400 W @ 26 knots. 60 knots is more than the double and then should the generator have given 3200 W, and that is unrealistic. It’s needed to be braked long before that.
Top wind velocity it uses to produce max wattage <> the need to brake.

According to Spreco, the generator has been tested to 65 knots without issue. Testing around this speed is pretty common I believe. Blades didn't go flying, generator was still working.

As you say, its not producing anymore power past 29ish knots but you do not need to tie it up until it until it hits 60ish. The regulator does have an overheat sensor so it should kick in well before that, and well before THAT ever happened, it would brake anyhow because the batteries would be fully charged.

Anyhow, if we were expecting 60 knot winds, I'd be binding the blades well before the wind hit.

UNCIVILIZED - there is a guy here in Marathon that has one of those flying now and I was admiring it. How well does it brake down for storage? Someday I may want to supplement my power and that seems like a great option.
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Old 03-04-2015, 19:49   #58
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Re: Silentwind Wind Generator

If you know of a source of Redwings, you'd make me REAL happy. Anyway, to answer your questions. The tail & shaft demounts with 2 machine screws. The prop with a single bolt. And the stainless arms on the hub, also, each have a single bolt.

Although in practice, it's simplest just to take off the tail, & then you've just got a 3' long prop & generator (with arms) assembly to stow. Done this way it's about as big as a 3' long section of 6" PVC pipe. Which is easy to find room for onboard usually.

Some folks will also fully disassemble them when underway, & thread a fitting into the generator for a line, onto which, they put a 3' shaft & an OB engine prop. Then rig up the generator portion to a stout, flexible mount, aft. And use it as a hydro-generator underway.
I never tried it, but the concept's more than sound & proven.
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Old 04-04-2015, 06:12   #59
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Re: Silentwind Wind Generator

OK, so no worries about the unknown "Chinch" connectors.

How about the idea about the remote stop switch: has anyone configured this switch to stop the generator by a BMS signal? I would assume that a relay would be required.

I'm thinking that it can be used as a back-up disconnect in case the auto-stop switch fails - so that I can leave the generator connected if leaving the boat..
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Old 04-04-2015, 06:18   #60
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Re: Silentwind Wind Generator

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Some folks will also fully disassemble them when underway, & thread a fitting into the generator for a line, onto which, they put a 3' shaft & an OB engine prop. Then rig up the generator portion to a stout, flexible mount, aft. And use it as a hydro-generator underway.

I never tried it, but the concept's more than sound & proven.
If yours is adaptable to a hydro conversion, you may want to consider it... I use Water/Wind combo unit from Hamilton Ferris, and it's one of my favorite pieces of gear...

I've never understood why more cruisers don't avail themselves of hydrogeneration on passages, it's a very impressive source of power underway... Whenever I see the ARC Gear Tests/Ratings written up in one of British magazines, water generators always seem to get very high marks from the comparatively small percentage of folks who use them... Excepting being plugged into shorepower, my batteries are rarely more fully topped up than during the course of a passage where I'm making decent boatspeed...

My boat is on the small side for a permanently mounted wind machine, and I don't care for the look of them anyway... Certainly more of an inconvenience to have to hoist it each time I want to use it, but the tradeoff is still worth it to me, and I think the 'floating' arrangement that comes from suspending the thing in the rig does go a long way in keeping the noise level down, and the blades well elevated and up in a cleaner airflow...


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