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Maretron/Airmar/Furuno ultrasonic wind sensors


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#1 Pukka

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Posted 26 March 2010 - 04:10 AM

Anybody had any real time experiences with above?
Apart from some R/F interference on the Maretron (google) and a decided unenthusiastic speil from the rep at ENL
on the PB-200, I am none the wiser.(Like, we don't stock it,go figure why.)
Seeing as they have been around awhile, it is curious.

I can't rationalise shelling 1500+ clams for a B&G & they don't output NMEA anyway,do they?

#2 New Morning

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Posted 26 March 2010 - 06:25 PM

Search Panbo.com Dan Corcoran did an extensive review on the second generation (aka 200) and loves it.

#3 Moonduster

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Posted 26 March 2010 - 08:48 PM

Tried to send you a PM but got some error saying "The member cannot use the messaging system" - perhaps you're not quite setup right?

PM me with some contact info ...

Basically, ultra sonic sensors have huge potential but don't seem very well developed for sailing. There's a reason that none of the high-end programs (AC, TP52, Volvo, etc) use ultrasonics - even at the expense of heavy and draggy 1.5 meter mast head wands.

Is your interest only lower cost? Are you aware that most NMEA interfaced systems are too slow to provide meaningful true wind data? What kind of instrumentation system are you trying to get this wind data into?

#4 Slowboat

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Posted 29 March 2010 - 12:30 AM

Moonduster - the PB200 does true wind direction and speed calculations in the transducer it's self. In addition to the ultrasonic wind sensor, it has a pretty sensitive WAAS GPS and 3-axis solid state compass. As I said, all the processing happens in the unit, so it can output the info over NMEA 0183 just fine. It also outputs via NMEA 2000, if you can use the data - perhaps into a computer, etc.

I would like to hear your thoughts on the downside of ultrasonic senors - I know that they can be screwed up by rain, fog and snow - are there other downsides?

You can read the Airmar info at:
http://www.airmartec....asp?ProdID=105

The PB200 WeatherStation instrument informs you of instantaneous changes in the weather around you. Wind Speed and Direction are measured using four ultrasonic transducers. No moving parts results in better durability and reliability. The internal WAAS GPS engine and three-axis, solid-state compass make it possible for the PB200 to provide both Apparent and True Wind Speed and Direction without the need to add on additional sensors. Additionally, the WAAS GPS provides navigation data as well as magnetic variation and is suitable as your primary GPS source. The internal temperature and barometric pressure sensors help predict changing weather patterns. Combined with the internal heading sensor, all of your navigation needs are provided! No other sensor on the market incorporates all of these sensors in one compact housing. What sets us apart from the PB100 and the competition is the ability to provide 2 heading accuracy under dynamic conditions, such as rough seas. Airmar's unique dynamic motion correction software is the key difference. The PB200's heading is highly accurate and stable under most sea conditions, even if the vessel is pitching and rolling up to 30 in rough seas. Also unique to the PB200 is that the 3D accelerometer and rate gyro are temperature compensated resulting in precise tilt and rate of turn data. This allows the PB200 to accurately measure True Wind Speed and Direction even when tilted up to 30.

#5 Pukka

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Posted 29 March 2010 - 11:12 PM

Search Panbo.com Dan Corcoran did an extensive review on the second generation (aka 200) and loves it.


Thanks for that. Comments after that article are interesting.

Moonduster-PM'd you. Presume it got there. (I did not have pm'g enabled.)

#6 DDW

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Posted 29 March 2010 - 11:59 PM

I bought a Maretron and never mounted it. One thing about a traditional wand, it gets it out in front of the usual antenna farm at the truck. These ultrasonics mount on a 1" pole, makes it a little hard to deal with. It would be nice if they would come up with one packaged for sailboats, not powerboats. Another issue is you have to run the Canbus cable up to the masthead.

I could probably be talked out of the Maretron at a substantial discount if you were interested. Seems to me that the Airmar is more sophisticated though.

#7 Sailing Harry

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Posted 29 September 2012 - 01:42 AM

Ok, I know this thread is over 2 years old. But my question is nearly identical, so why start a new one.

The PB200 sounds terrific. Some say it isn't up to Grand Prix performance -- but not much at this price range is!

What I see as "plus"
* Includes magnetic compass -- so outputs ground wind at anchor
* Outputs NMEA 0183 wind --works with my old autopilot
* Outputs NMEA 2000 -- works with new instruments
* Can't be broken by birds
* Includes GPS (who can't use a spare -- perhaps dedicated to DSC VHF?)

What I see as "minus"
* At this price and benefits, how come they aren't pushing 5-10% market share? Why are few folks talking about them?
* How best to mount at masthead?
* Is the magnetic compass nearly worthless in a seaway? I only sail the Chesapeake, not the Southern Ocean.
* How come no one "bundles" it? I'm looking at a GMI10 system -- the included wind unit is $500, the PB200 is $1200 -- but a-la-carte the GMI10 is VERY expensive!

Any updated thoughts on the ultrasonic systems? Panbo seems to have about 95% of the total internet discussion on this item!

#8 mike_new

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Posted 01 October 2012 - 03:15 PM

Ok, I know this thread is over 2 years old. But my question is nearly identical, so why start a new one.

The PB200 sounds terrific. Some say it isn't up to Grand Prix performance -- but not much at this price range is!

What I see as "plus"
* Includes magnetic compass -- so outputs ground wind at anchor
* Outputs NMEA 0183 wind --works with my old autopilot
* Outputs NMEA 2000 -- works with new instruments
* Can't be broken by birds
* Includes GPS (who can't use a spare -- perhaps dedicated to DSC VHF?)

What I see as "minus"
* At this price and benefits, how come they aren't pushing 5-10% market share? Why are few folks talking about them?
* How best to mount at masthead?
* Is the magnetic compass nearly worthless in a seaway? I only sail the Chesapeake, not the Southern Ocean.
* How come no one "bundles" it? I'm looking at a GMI10 system -- the included wind unit is $500, the PB200 is $1200 -- but a-la-carte the GMI10 is VERY expensive!

Any updated thoughts on the ultrasonic systems? Panbo seems to have about 95% of the total internet discussion on this item!


One of the PROs told me last week that they are no good, at least for Racing.
Here is another one:
www.lcjcapteurs.com/ (web refurbishement in progress)

#9 savoir

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Posted 02 October 2012 - 11:01 PM

To admit that ultra sonic sensors are good for racing is to put a hell of a lot of products into the trash can.

If you get one, don't put it on the masthead - they are too sensitive for up there.

#10 VALIS

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Posted 03 October 2012 - 08:12 PM

To admit that ultra sonic sensors are good for racing is to put a hell of a lot of products into the trash can.

If you get one, don't put it on the masthead - they are too sensitive for up there.


"too sensitive up there"? Please explain. If you mean that they respond instantly to masthead motion induced wind, then isn't that a good thing as long as the speed / direction vector is accurate? Does the inertial damping of the mechanical-style windex somehow improve the resulting data?

#11 henry the navigator

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Posted 03 October 2012 - 10:54 PM

SDD and peer pressure is the reason you don't see them. SDD = Sailor Decision Disorder.

Tested above to a B/G static detector about 100' up for a season. No problems.

#12 Barley

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Posted 09 October 2012 - 06:56 PM

Ok, I have been using a ultra sonic detector for the past 3 years. It is the Airmar PB 250. It is connected to an Ockam system via a custom Ockam interface. Mast height is 75 feet.

1st: You need a really sturdy mount. The detector weighs a ton compared to the old 36 inch bent wand. The inertia is impressive. I think my current mount is about 20 inches high. When you hold it/swing it around the amount of force that weight exerts on the bottom end is alot more than I expected. Now add another 75 feet to that. Going upwind in moderate waves must create huge forces. Because of this, I am thinking about having the wand shortened to about 10 inches.

2nd: I have been told, no personal experience, that the compass is useless up there. The amount of motion is just too much. Look at the top of you mast in small waves and see how much it moves around compared to the deck and you quickly get an idea how hard it would be for a compass to give quality readings. Same for the gps.

3rd: It also gives temp and barometric pressure. Sure not the most useful info on a racing boat but its available. We use the barometric pressure reading and its trends just to track the weather.

4th: They are really accurate and really sensitive. But you have to put some effort into setting up the averaging to get quality data for the instruments to use. If the averaging is too slow the delay will drive you insane. You feel the lift and 20 seconds later the instruments show it. Too fast and you get crazy data, for example in light wind conditions with waves causing the mast to move back and forth you get useless data. Still not totally happy but working on finding a happy medium. Now I know this is true with any system but I will tell you its more pronounced with the ultrasonic detectors. Their data has no delays. With the traditional wind indicator you have to overcome inertia, etc. However it is really cool on a still morning to watch the wind speed indicator pick up speeds of .2 to .9 knots and the wind direction indicator is showing the direction, while you look over at all the surronding boats (including those with higher masts) and there tradition wind detectors are not moving

So why are they not popular. Well I think the weight is a real issue. I am still considering going back to a traditional bent wand not just because of the classic "limit weight up-top issues" which is very important, but because of the tremendous forces it is applying to the mast mount. Not sure I want to be on a long upwind slog to Bermuda and hope the mount lasts. Also the standard bent mount is way cooler looking than the strait mount for the ultrasonic detector. Not really that important but just saying. Also do many current instrument systems have a "cheap" way to intergrate a ultasonic detector. Mine was very expensive (I know its Ockam), but what about everyone else, B&G, NKE, Raymarine, Nexus, etc. I didn't realize those compaines had interfaces.

In a perfect world ultrasonics should rule. If the weight was less. Cost was less. Easy intergration into curent systems. Then maybe you would see more of them

#13 Presuming Ed

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Posted 10 October 2012 - 12:34 PM

Accuracy of the Airmar doesn't look great when it's raining? From the specs:

Wind Speed Accuracy @ 0°C to 55°C (32°F to 131°F), no precipitation*:
— Low Wind Speeds: 0 knots to 10 knots (0 MPH to 11.5 MPH); RMS error of 1 knot (1.1 MPH) +10% of reading
— High Wind Speeds: 10 knots to 80 knots (11.5 MPH to 92 MPH); RMS error of 2 knots (2.3 MPH) or 5% RMS, whichever is greater
Wind Speed Accuracy in wet conditions**: 5 knots (5.7 MPH) RMS

#14 NewLeaf

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Posted 14 October 2012 - 04:10 AM

Tried to send you a PM but got some error saying "The member cannot use the messaging system" - perhaps you're not quite setup right?

PM me with some contact info ...

Basically, ultra sonic sensors have huge potential but don't seem very well developed for sailing. There's a reason that none of the high-end programs (AC, TP52, Volvo, etc) use ultrasonics - even at the expense of heavy and draggy 1.5 meter mast head wands.

Is your interest only lower cost? Are you aware that most NMEA interfaced systems are too slow to provide meaningful true wind data? What kind of instrumentation system are you trying to get this wind data into?

I know of 2 programs using the ultrasonic sensors in the AC, Team NZ and Artemis. TNZ even put out a video while calibrating the wands with the ultrasonic as reference.....

#15 Moonduster

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Posted 14 October 2012 - 04:50 PM

You've missed the boat. They're calibrating the wands because they're not using the ultrasonic on the boat. It's a fine reference in a test setup, but not so much use on a yacht.

#16 henry the navigator

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Posted 19 October 2012 - 01:24 AM

Moonduster,

Are you suggesting the ultrasonic sensor is being used to calibrate the analog wind sensor?

Is the ultrasonic sensor too heavy to use while sailing?

Have you seen many problems using the ultrasonic sensor?

What is the wind sensor of choice now?



#17 diggler

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Posted 19 October 2012 - 07:43 AM

Anyone know of any work that has been done on characterizing the off axis response of these ultrasonic units? Horizontal axis turbines like the Nexus have a nice cosine response, vertical axis cup anemometers do some odd things but assuming something close to constant over normal heel angles usually seems to work out ok. But these? I imagine the vendor specific design of the measurement gap would have a big impact, and it won't be anything linear - next to zero at small heel angles and dropping off very quickly above some threshold where the gap stalls out.

#18 mowgli

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Posted 21 October 2012 - 08:24 AM

I was thinking about to instal one in the center on the back off the boat on a small pole. How accurate are the readings then also with a normal transducer?
On my new boat I have a rotating mast so I don't need a mast rotation compensatort and for trailering you don't have to dismantle it from the mast. Any thought about this setup.

#19 nyker

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Posted 21 October 2012 - 09:12 PM

When sailing close hauled the sensor will be in the ' downdraft' of the sail and the reading will be inaccurate. I will have the same problem for my F85SR. I allready thought about using 2 sensors on poles on the aft beam ends and using a heal switch to select the upwind sensor. I understand that the airflow, only a few meters above the water will be too turbulent for autopilot use. But it might be ok for instruments.

#20 diggler

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Posted 22 October 2012 - 08:25 AM

This makes no sense. For the cost of two sensors and a heel switch you can get a mast rotation compensator and put one sensor on the mast and actually get useful data.

#21 savoir

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Posted 22 October 2012 - 10:56 AM

When sailing close hauled the sensor will be in the ' downdraft' of the sail and the reading will be inaccurate. I will have the same problem for my F85SR. I allready thought about using 2 sensors on poles on the aft beam ends and using a heal switch to select the upwind sensor. I understand that the airflow, only a few meters above the water will be too turbulent for autopilot use. But it might be ok for instruments.


" too turbulent for autopilot use " ? Who says that ?

#22 mowgli

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Posted 22 October 2012 - 01:56 PM

This makes no sense. For the cost of two sensors and a heel switch you can get a mast rotation compensator and put one sensor on the mast and actually get useful data.


Is there a mast rotation compensator that will work with a PM200?
Airmar don't have one so far I know.

#23 diggler

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Posted 22 October 2012 - 05:05 PM

Is there a mast rotation compensator that will work with a PM200?
Airmar don't have one so far I know.


No, not that I am aware of. For that you'd need to roll your own. Not terribly difficult to do if you go with the 0183 version and an Arduino, but you do have to have the inclination. Or really long, cold, dark winters...

I remember reading about some guys over on one of the Yahoo F-boat groups that liked the results they got from putting a PB200 on the bow sprit. Since the apparent is rarely aft of the beam on those boats I guess it is probably about the best option after the mast head, as long as you aren't sailing in really rough stuff and dunking the unit a lot.

My comment to Nyker was implying dropping the ultrasonic sensor and going with one of the few instrumentation systems around that accomodates rotating masts, like Nexus. Maybe lacking motion compensation for the wind sensor, but overall a much more useful instrumentation system.

#24 mowgli

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Posted 22 October 2012 - 06:34 PM


Is there a mast rotation compensator that will work with a PM200?
Airmar don't have one so far I know.


No, not that I am aware of. For that you'd need to roll your own. Not terribly difficult to do if you go with the 0183 version and an Arduino, but you do have to have the inclination. Or really long, cold, dark winters...

I remember reading about some guys over on one of the Yahoo F-boat groups that liked the results they got from putting a PB200 on the bow sprit. Since the apparent is rarely aft of the beam on those boats I guess it is probably about the best option after the mast head, as long as you aren't sailing in really rough stuff and dunking the unit a lot.

My comment to Nyker was implying dropping the ultrasonic sensor and going with one of the few instrumentation systems around that accomodates rotating masts, like Nexus. Maybe lacking motion compensation for the wind sensor, but overall a much more useful instrumentation system.


Diggler tanks for the comment, I am going in november to the Mets and going to visit the Airmar stand maybe I can talk the in to develop a software option for it to work with a other digital compass on the boat to calculate the rotation of the mast. (the pb200 has its one compass build in)

#25 Moonduster

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Posted 22 October 2012 - 07:51 PM

Couple of comments:

Henry,

I'm not suggesting it - that's what the video implies. Take a look for yourself.

Mowgli,

Deck level sensors aren't ideal. Neither is having the sensor so far aft will cause weird effects due to apparent wind that is induced as the boat's stern slews around, especially when surfing off down wind - this can cause significant oscillation problems when feeding wind direction data to an auto pilot. Also be careful about the amount of spray that might wind up directed into the sensor when sailing up wind - take a look at the derating for accuracy in the rain and then multiply that a few times for the effects of sheet spray.

Regarding mast rotation -

NKE, B&G and Nexus all support mast rotation sensors. Either Nexus or NKE uses a clever dual compass approach where one compass is the normal fixed compass and the other in mounted inside or onto the mast. The differential of the two compasses is mast angle. The problem is that compasses aren't super accurate and there's no synchronization in the time domain of the two compasses so it's easy to induced 1-4 degrees of rotation error and that has a huge effect on the true wind direction math and, worse yet, it's prone to oscillation problems.

I'm not aware of any other commercial solution that has direct support for rotating masts, although I'm sure that the Cosworth system, not exactly an off-the-shelf solution, does too.

#26 nyker

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Posted 22 October 2012 - 09:38 PM

This makes no sense. For the cost of two sensors and a heel switch you can get a mast rotation compensator and put one sensor on the mast and actually get useful data.


Money wise you are right.There is a drawback however. Mast rotation compensators are not very accurate up till now as there are fluctuations in the compass readings which add up. On trimarans there is often a big difference between AWS and TWS, This means that a few degrees of uncertainty has a lot of influence.


" too turbulent for autopilot use " ? Who says that ?


That is what Woolfy ( nexus ) wrote when I mailed him some questions about using TWS and the possibility of using a heel switch for selecting the upwind sensor. Wind direction and speed @ 2 meters above sealevel seems to be more turbulent than at mast level.

It will be a few years before my boat is ready and I hope that there is a good solution by then. I think it would be nice to have a modified rudder angle transmitter coupled to the wind information. This rules out compass variations.

#27 diggler

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Posted 23 October 2012 - 06:25 AM

Money wise you are right.There is a drawback however. Mast rotation compensators are not very accurate up till now as there are fluctuations in the compass readings which add up.


What do you mean, add up? There is no integration of the angle, so the error is the error. The Nexus system really heavily dampens the mast compass value, so unless you have one of those special boats that manages to roll a few more degrees to port than starboard every oscillation, you should be fine dynamically which just leaves you with hard iron errors.

No system that I am aware of makes any effort to account for the hysteresis inherent in the response of cup anemometers which leads to increasingly overestimated wind speeds with increasing turbulence. Most systems make no allowance for leeway, and those that do tend to use a pretty rough approximation. Unless you splash out big bucks on the reasonably fast NKE ultrasonic sensor, you are measuring speed with a paddlewheel or a very slow airmar sensor. Errors in the boat speed vector are as just as significant as those in the apparent wind vector.

My point here is that I think you are worrying far too much about one source of error to the exclusion of others and the system you are contemplating will suffer even poorer performance for it.

NKE, B&G and Nexus all support mast rotation sensors. Either Nexus or NKE uses a clever dual compass approach where one compass is the normal fixed compass and the other in mounted inside or onto the mast.

This NKE mast rotation sensor
http://www.nke-marin...unt-sensor.html
is quite clearly not a compass. It is in fact exactly what Nyker was asking for. The price for a full NKE system hurts too much for me. Sure would be nice to have one of their pilots though.

#28 savoir

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Posted 23 October 2012 - 08:31 AM


This makes no sense. For the cost of two sensors and a heel switch you can get a mast rotation compensator and put one sensor on the mast and actually get useful data.


Money wise you are right.There is a drawback however. Mast rotation compensators are not very accurate up till now as there are fluctuations in the compass readings which add up. On trimarans there is often a big difference between AWS and TWS, This means that a few degrees of uncertainty has a lot of influence.


" too turbulent for autopilot use " ? Who says that ?


That is what Woolfy ( nexus ) wrote when I mailed him some questions about using TWS and the possibility of using a heel switch for selecting the upwind sensor. Wind direction and speed @ 2 meters above sealevel seems to be more turbulent than at mast level.

It will be a few years before my boat is ready and I hope that there is a good solution by then. I think it would be nice to have a modified rudder angle transmitter coupled to the wind information. This rules out compass variations.


Oh well, my PB 200 works just fine at 4m above sea level. My only problem is too much data. A project for next summer is using the averaging function to try and settle it down.

#29 mowgli

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Posted 23 October 2012 - 09:48 AM



This makes no sense. For the cost of two sensors and a heel switch you can get a mast rotation compensator and put one sensor on the mast and actually get useful data.


Money wise you are right.There is a drawback however. Mast rotation compensators are not very accurate up till now as there are fluctuations in the compass readings which add up. On trimarans there is often a big difference between AWS and TWS, This means that a few degrees of uncertainty has a lot of influence.


" too turbulent for autopilot use " ? Who says that ?


That is what Woolfy ( nexus ) wrote when I mailed him some questions about using TWS and the possibility of using a heel switch for selecting the upwind sensor. Wind direction and speed @ 2 meters above sealevel seems to be more turbulent than at mast level.

It will be a few years before my boat is ready and I hope that there is a good solution by then. I think it would be nice to have a modified rudder angle transmitter coupled to the wind information. This rules out compass variations.


Oh well, my PB 200 works just fine at 4m above sea level. My only problem is too much data. A project for next summer is using the averaging function to try and settle it down.


Where is your PB200 place on your boat?

#30 savoir

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Posted 23 October 2012 - 11:53 AM

It sits on an antenna pole on the port quarter.

#31 nyker

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Posted 23 October 2012 - 04:02 PM

What do you mean, add up?


I'm not talking about dynamic variations caused by mast movement. These will generally be filtered out. Most mast rotation compensators use a second compass on the mast to compare headings with the main compass and calculate apparent wind direction. For total system accuracy you have to add their inaccuracy values as the two compass readings are used to calculate wind direction.


I know Maretron have a solid state compass that they claim has an accuracy of 1° ( under static conditions ) but most compasses have a lower accuracy.


I've seen the NKE sensor and agree with you on the price issue :rolleyes: :(


regards

Nico



#32 diggler

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Posted 23 October 2012 - 04:20 PM

Ahh, see what you mean by adding up. Duh.

#33 Aremmes

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Posted 25 October 2012 - 09:06 PM

Couldn't the PB200 compare its compass reading with the GPS heading (provided that it knew the local magnetic variation) to compensate for mast rotation? If Airmar can't include it in a firmware update, maybe they should be working on a follow-up to the 200WX.

#34 nyker

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Posted 26 October 2012 - 06:44 AM

No. Because then you also have to correct for drift and current.


#35 diggler

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Posted 26 October 2012 - 09:17 AM

It has also been pretty well established that the compass and gps data from the PB200 is fairly useless if it is flopping about at the top of a mast.

#36 TACNI

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Posted 31 October 2012 - 03:24 PM

I believe Ockam systems can use a mast rotation sensor like a string pot to correct for mast rotation. A much better way than using the difference in heading between the boat and the mast.

#37 Moonduster

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Posted 31 October 2012 - 06:14 PM

The complication with the string-pot approach is that the string usually winds around the mast as it rotates in at least one direction and, as a result, the string motion isn't linear with mast rotation. It's a manageable problem, but a bitch to construct the tables to translate between the coordinate spaces.

And string pot reliability isn't so great.

#38 mowgli

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Posted 22 November 2012 - 07:44 PM

I did find the following on the site of lcjcapteurs:


Option CV7-C-CanBus :

CV7-C Canbus is compatible with NMEA2000® systems featuring a wind functions page.
The CanBus option includes a barometer (suitable for systems featuring a barometer functions page).
This option is available by adding a "Black-Box" interface.
These instruments have been tested with the CV7-Canbus:
B&G© : Triton.
Furuno©: FI50, RD33, NavNet2, NavNet3.
Garmin© : GMI10 (whole range).
Raymarine©: i70.
Simrad© : whole range.

Option CV7-C-RM:

CV7-C-RM for sailboats with rotating mast.
CV7-C-RM allows connecting the CV7 mast head sensor to any NMEA2000® compatible instruments.

http://www.lcjcapteurs.com/product/cv7-c-is-the-high-speed-ultrasonic-wind-sensor/?lang=en

#39 patrik111

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Posted 06 February 2013 - 09:55 PM

It has also been pretty well established that the compass and gps data from the PB200 is fairly useless if it is flopping about at the top of a mast.


Reading the panbo writeup I would much like to read the "other side", where can I find that?

#40 Sailing Harry

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Posted 12 February 2013 - 03:11 AM

It has also been pretty well established that the compass and gps data from the PB200 is fairly useless if it is flopping about at the top of a mast.


Seems I lost track of this thread -- and it's one I'm pretty interested in. But I'm back.

Where/how has it been established, by real users (not theoreticists, but users) that the compass/GPS data is bad because it's at the mast head?

I can accept that the GPS is poor, since it takes position fixes every few instants and uses that for data. I think one user I read of took a hand held gps and waved it around his body, and got wild results. I know my handheld can get course/speed when I simply walk across my 20' patio! But if you use the GPS for nothing but a backup nav source, I'm very happy with 50' error readings!

The compass is different. There is ZERO inertia, and inertia is what makes your card-compass spin when you shake it. The compass may move violently, but it does NOT rotate, at least not much, and identically to the rotation of the boat. The flux direction through the compass is constant as the compass thrashes, and so should produce a steady result. It is true that the compass will rotate around a horizontal axis, and that coupled with the vector math will induce errors, but the PB200 has a 3-axis compass and should be able to calculate that out.

The compass is one big factor in this decision. A typical windmill sensor is $500, perhaps more. A typical NMEA 2000 compass to add to the sensor mix is at least another $500. That makes the price of the PB200 tempting -- but if the compass is of no value, then it looses its charm.

I'd love to hear actual users who actually installed the unit and found the compass to be a problem.

And while compass readings that bounce around by 1 or 2 degrees may be an issue for people that have $50K annual budgets (and those people think nothing of replacing wind units every time an Osprey sits on it!), us cruisers will be very happy with a +/- 3 degree unit if it works fine and never dies from an Osprey.

Harry

#41 diggler

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Posted 12 February 2013 - 07:43 PM

read about flux gate compass sensors and their sensitivity to accelerations. way bigger errors than one or two degrees.

#42 snikabo

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Posted 18 February 2013 - 10:27 PM

Hi

I've read trough the entire thread and non the wiser.

I'm looking for a reliable wind sensor to be used on a weather buoy.
As I understand Airmar pb-150 calculates TWD automatically, so if the buoy rotates its corrected.
There is less maintenance with an ultrasonic sensor compared to a cup/vane sensor.

One drawback is that concerns me is accuracy when it rains, how bad is it?

Is there any other wind sensor system better suited for use on weather buoys?


Snikabo

#43 crashdog

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Posted 18 February 2013 - 10:49 PM

i've just ordered LCJ Captuers CV-7 C from Pochon. I have no idea if it will work at all, and since I often forget to put the instruments on when I go sailing, I am not sure if I can accurately compare it to anything at all. After all, we never had no stinkin wind instruments in the Star.

However, Vancouver has frustratingly light air, and the mast tip motion caused by the crew reaching for their beer is going to introduce a substantial error into the wind calc so it will be an ideal environment to test accuracy. I will report in due time.

#44 diggler

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Posted 19 February 2013 - 09:26 PM

One drawback is that concerns me is accuracy when it rains, how bad is it?


I've not been able to find any good info on this either. Looking forward to hearing how crashdog does with his unit. If there was a decent chandler near me I would just buy one and test it.

I also haven't found any good info on how the response of these units changes with heel/pitch angle. I expect there is a nice operating pocket outside of which things get very non-linear very quickly. Could be an issue if your weather buoy is going to see some big waves.

#45 WHL

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Posted 22 February 2013 - 10:52 PM

i've just ordered LCJ Captuers CV-7 C from Pochon. I have no idea if it will work at all, and since I often forget to put the instruments on when I go sailing, I am not sure if I can accurately compare it to anything at all. After all, we never had no stinkin wind instruments in the Star.

However, Vancouver has frustratingly light air, and the mast tip motion caused by the crew reaching for their beer is going to introduce a substantial error into the wind calc so it will be an ideal environment to test accuracy. I will report in due time.

The big question is: will it get you past Raven ?? :)

#46 crashdog

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Posted 22 February 2013 - 11:54 PM

Maybe if it blows. The boat is sticky in light air. Maybe the instrument will be able to tell me when its too light to bother...

#47 savoir

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Posted 23 February 2013 - 09:00 AM

You should mount it on an antenna pole - if you have one.

#48 nyker

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Posted 30 August 2013 - 06:51 PM

Looking at recent AC ( Artemis bow sprit) and little AC pics (Hydro C-class), would it be an idea to keep the ( solar powered and wireless ) CV7SF on a jackstaff on top of the bowsprit navlights?
 
windmeter.jpg23vnc00.jpghydro-51.jpg

#49 NewLeaf

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Posted 01 September 2013 - 03:07 PM

Moonduster, I did not miss the boat I was on the boat. Both teams were using the regular wands to validate the concept and the they were used in conjunction with regular wands.

Look at the some of pictures and you will see not just one but 3 ultrasonic sensors, 2 at the stern.

Don't believe me it is OK, not here to get on a piss off match. Just to report their knowledge without anything to gain.

 

Tried to send you a PM but got some error saying "The member cannot use the messaging system" - perhaps you're not quite setup right?

PM me with some contact info ...

Basically, ultra sonic sensors have huge potential but don't seem very well developed for sailing. There's a reason that none of the high-end programs (AC, TP52, Volvo, etc) use ultrasonics - even at the expense of heavy and draggy 1.5 meter mast head wands.

Is your interest only lower cost? Are you aware that most NMEA interfaced systems are too slow to provide meaningful true wind data? What kind of instrumentation system are you trying to get this wind data into?

I know of 2 programs using the ultrasonic sensors in the AC, Team NZ and Artemis. TNZ even put out a video while calibrating the wands with the ultrasonic as reference.....


#50 quasi-expert

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Posted 02 September 2013 - 03:43 PM

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.



#51 mowgli

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Posted 02 September 2013 - 08:38 PM

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.

You probably have not seen this and those guys are not stupid.

https://www.youtube....h?v=93jTPOeNVQQ

They use a Airmare as calibration for there Nexus instruments.

I self had a  LCJ Captuers and it work very good. On my new boot I will buy on again.



#52 quasi-expert

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Posted 03 September 2013 - 04:09 PM

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.

You probably have not seen this and those guys are not stupid.

https://www.youtube....h?v=93jTPOeNVQQ

They use a Airmare as calibration for there Nexus instruments.

I self had a  LCJ Captuers and it work very good. On my new boot I will buy on again.

 

I would rather do it the other way around.



#53 mowgli

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Posted 04 September 2013 - 06:37 PM

 

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.

You probably have not seen this and those guys are not stupid.

https://www.youtube....h?v=93jTPOeNVQQ

They use a Airmare as calibration for there Nexus instruments.

I self had a  LCJ Captuers and it work very good. On my new boot I will buy on again.

 

I would rather do it the other way around.

The guy's in Falmouth are stupid also? 

http://forums.sailin...=5#entry4282494



#54 quasi-expert

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Posted 05 September 2013 - 12:52 PM

 

 

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.

You probably have not seen this and those guys are not stupid.

https://www.youtube....h?v=93jTPOeNVQQ

They use a Airmare as calibration for there Nexus instruments.

I self had a  LCJ Captuers and it work very good. On my new boot I will buy on again.

 

I would rather do it the other way around.

The guy's in Falmouth are stupid also? 

http://forums.sailin...=5#entry4282494

Not saying they are stupid, but the test I was referring to used a laser doppler velocimeter as reference and all of the ultrasonic anemometers were off at one time or the other (speed, angle, both). Of course these things are lighter and wireless etc. but I wouldn't use one as long as it was checked individually for accuracy. Among those sensors tested three were identical and they all gave different measurements.



#55 patrik111

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Posted 06 September 2013 - 06:34 AM

 

 

 

I have seen results of extensive ultrasonic anemometer (various brands) testing and I can only recommend NOT to buy one for sailing yachts.

windspeed was inaccurate, wind angle was very inaccurate.

Deviations from target for both values changed with wind angle so you cannot even calibrate them to have proper measurements.

For comparison a standard sailing system was tested alongside and prooved to be very accurate.

You probably have not seen this and those guys are not stupid.

https://www.youtube....h?v=93jTPOeNVQQ

They use a Airmare as calibration for there Nexus instruments.

I self had a  LCJ Captuers and it work very good. On my new boot I will buy on again.

 

I would rather do it the other way around.

The guy's in Falmouth are stupid also? 

http://forums.sailin...=5#entry4282494

Not saying they are stupid, but the test I was referring to used a laser doppler velocimeter as reference and all of the ultrasonic anemometers were off at one time or the other (speed, angle, both). Of course these things are lighter and wireless etc. but I wouldn't use one as long as it was checked individually for accuracy. Among those sensors tested three were identical and they all gave different measurements.

Is it possible to see a link to those tests? or other public tests? Above are many claims that it does not work well, but few references are given.

 

Another question,

The wind instrument on the PB200 should compensate for movements through calculations with data from accelerometers and gyros in the unit, does anyone know if this is also done/could be done for the GPS? Seems a way to get around problems with mast-head mounting.



#56 samc99us

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Posted 06 September 2013 - 03:59 PM

Test results would be nice. Placing that much mass at the top of a mast isn't really a good option for any boat though, and you have limited mounting options on conventionally rigged boats with foresails. Still, eventually this technology with be reduced in size. How do the laser doppler measurements compare with normal anemometers?

 

Compensating for 3-axis boat movement using a 3D GPS fix with accuracy only guaranteed to 10 ft (real-world is much better) won't do it. You need accelerometers and gyros. A differential GPS setup might help, I am curious of the latter has been tested on the AC72's, but really this only improves positional accuracy and for a sensor you can measure it's position twice and set that location in the filter.



#57 crashdog

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Posted 08 September 2013 - 08:47 AM

Just a quick note on the CV-7 I bought from Pochon (as recommended by LCJ).  Straight out of the box it has been better than any wind instrument I have ever used and weight aloft is also less than any other whirlygig I have used in the past..  Had to build a funky little electronic device so that I could adequately calibrate it with my Nexus system, but that only took a couple of minutes.  

 

I am in the PNW so I haven't tested the device in heavy air, but have had a couple of + 20 blows and the instrument seemed to adequately compensate for both roll and pitch in big waves.  As I use the device more I am coming to the conclusion that there are errors that occur at medium deep running angles - 160 to 175 degrees, and so I need to work up some sort of compensation table to put into the setup.

 

My dealings with Pochon were absolutely great - they made the purchase quite easy.  LCJ has also been a pleasure to deal with.  Would buy again and would highly recommend.  



#58 quasi-expert

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Posted 09 September 2013 - 04:18 PM

Test results would be nice. Placing that much mass at the top of a mast isn't really a good option for any boat though, and you have limited mounting options on conventionally rigged boats with foresails. Still, eventually this technology with be reduced in size. How do the laser doppler measurements compare with normal anemometers?

 

Compensating for 3-axis boat movement using a 3D GPS fix with accuracy only guaranteed to 10 ft (real-world is much better) won't do it. You need accelerometers and gyros. A differential GPS setup might help, I am curious of the latter has been tested on the AC72's, but really this only improves positional accuracy and for a sensor you can measure it's position twice and set that location in the filter.

 

As said above the normal anemometer was accurate. Unfortunately the test results are not public which is why I am not posting brand names etc.

As there development continues I am sure these things will get better and eventually be more precise than current mechanical anemometers. There are also different designs available some being better than others.



#59 diggler

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Posted 10 September 2013 - 12:23 PM

Just a quick note on the CV-7 I bought from Pochon (as recommended by LCJ).  Straight out of the box it has been better than any wind instrument I have ever used and weight aloft is also less than any other whirlygig I have used in the past..  Had to build a funky little electronic device so that I could adequately calibrate it with my Nexus system, but that only took a couple of minutes.  

 

I am in the PNW so I haven't tested the device in heavy air, but have had a couple of + 20 blows and the instrument seemed to adequately compensate for both roll and pitch in big waves.  As I use the device more I am coming to the conclusion that there are errors that occur at medium deep running angles - 160 to 175 degrees, and so I need to work up some sort of compensation table to put into the setup.

 

My dealings with Pochon were absolutely great - they made the purchase quite easy.  LCJ has also been a pleasure to deal with.  Would buy again and would highly recommend.  

 

Any comments on performance in rain/fog?



#60 crashdog

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Posted 11 September 2013 - 06:22 AM

 I haven't noticed a difference in rain.  There may be more variability in higher temperature, or at least I feel there is - maybe i am just looking for it.  I havent sailed the boat in fog, but the fall around here is high humidity so I may have better reports then.



#61 mowgli

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Posted 21 October 2013 - 06:29 PM

 a update on the LCJ Capteurs, they have a rotating mast option now and is N2K

http://www.lcjcapteu...france/?lang=en



#62 foshizzle

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Posted 21 October 2013 - 11:24 PM

It's already been said, but the ultrasonics weigh more, and are much less accurate with respect to angle and wind speed than the masthead instruments with mechanical arms sensing wind angle spinning anemometers for wind speed.  The ultrasonic instruments should not be used to calibrate a damn thing except maybe to calibrate you licking your finger and holding it into the wind to judge speed and direction, because its about the only thing I can think of that is less accurate.  The only advantage to them is that mechanical instruments should be serviced regularly to maintain their accuracy, whereas the ultrasonic devices should maintain their sub-par accuracy for much longer without being serviced.

I think they would be fine for many cruisers, but I would question their use on a race boat. That said, you should be able to race without relying on wind speed and direction readings, but if you have it as a racer, you want accurate info.

#63 crashdog

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Posted 22 October 2013 - 08:19 AM

Would you be able to cite sources for accuracy, weight, etc?  Nearest I can tell is B&G/Simrad/tacktic transducers at 230g, CV7-C at 150g.  Certainly the CV7-C was substantially lighter than the Nexus NWind Race it replaced so in this case, no, it didn't weigh more.  Not sure about accuracy, since I generally steer by the wind on the water, occasionally by looking at the masthead fly, and not by looking at a screen.   Any "accuracy" problems I have experienced are a problem with my set up rather than with the instrument.  I would say that what the instrument reads at 21m is correlates very well with the reported 10m datum wind as well as with my read of the wind on the water, between about 3 knots and 25 TWS.  But that is just me.  I haven't seen a comparative review.



#64 foshizzle

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Posted 22 October 2013 - 11:33 AM

For the Airmar 200WX the wind speed accuracy is published as 1 knot plus 10% for wind 0-10 kn in dry conditions.  This means that at 10 knots, it may read as much as 20% off.  In wet conditions, the accuracy is worse.  The wind direction accuracy is published as 5% RMS in dry conditions for wind speeds 10 kn or less which translates to 18 degrees.  The fact that RMS values are shown implies oscillation, and this also means that the actual amplitude of the error is  30% higher than that (unless the RMS value is transmitted from the device).  Again, it is worse in wet conditions.  

 

The more conventional masthead mechanical devices are more accurate because there is a direct correlation between a mechanical device and what it is measuring.  For wind direction, the vane is designed such that it points directly into the wind.  As long as there isn't something stuck to it that causes it to be unbalanced, the device will continue to point directly into the wind.  The only published accuracy I could find was +/- 1 degree. For wind speed, the anemometer design is bench tested and calibrated to produce a certain rotational speed at a given wind speed.  I have not seen published errors for the devices, but as with wind direction, unless there is a mechanical fault or defect, the speed/rotation relationship will hold.  The error in the ultrasonic device is a result of the fact the data is calculated, it is inferred from ultrasound propagation measurements instead of being directly measured as with the mechanical devices.  

 

The choice comes down to a device that is more robust but less accurate (ultrasonic), or more accurate, but susceptible to wear and damage (mechanical).  There are no commercial devices I can find that are robust and accurate.  Measurement of something as simple as wind speed, wind direction, and even humidity is more difficult than it sounds particularly within the constraints of making the device affordable to the average sailor.



#65 Moonduster

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Posted 22 October 2013 - 04:26 PM

In a world where cost doesn't matter and the value of an accurate wind triangle is immeasurable, every AC team uses the B&G wand. No one uses ultra sonics.



#66 NewLeaf

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Posted 22 October 2013 - 04:33 PM

not ALL the teams, there was a team using the NKE perf/regatta wand and 3 of the ultrasonic (home grown and developed from the Airmar) with substantial code changes which was used in conjunction with the NKE

In a world where cost doesn't matter and the value of an accurate wind triangle is immeasurable, every AC team uses the B&G wand. No one uses ultra sonics.



#67 VENTS

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Posted 22 October 2013 - 04:54 PM

The Airmar unit you refer to is designed around the CV3F technology that Lcj Capteurs licenced to Airmar in 2002. Since then the technology has progressed and the current CV7 available from LCJ Capteurs in 2013 shows much better performance. This is illustrated in the attached diagram:

http://www.lcjcapteu...Vs-CV7_2011.pdf



#68 foshizzle

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Posted 22 October 2013 - 08:12 PM

Thank you for the information.  It's good to see the technology has progressed.  That's quite a nice device.  By the looks of it it has the accuracy to be a reasonable selection for race boats.  I'm going to look into it for my Pearson - time to get rid of the 30 year old B&G wind instrument.

The Airmar unit you refer to is designed around the CV3F technology that Lcj Capteurs licenced to Airmar in 2002. Since then the technology has progressed and the current CV7 available from LCJ Capteurs in 2013 shows much better performance. This is illustrated in the attached diagram:

http://www.lcjcapteu...Vs-CV7_2011.pdf



#69 Moonduster

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Posted 23 October 2013 - 02:13 AM

What team used an ultra sonic device on board during a regatta?






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