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Old 16-12-2012, 14:10   #1
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Maretron vs. Airmar Ultrasonic Wind

Just about to place a massive order for all new electronics and having some last minutes thoughts.

I have been planning to use the Maretron WSO100 wind sensor because it is lighter (important at the masthead), less bulky (ditto), and cheaper. It's got no gps, compass, or rate gyro, which is only needed for freestanding weather station use (I will have better position and heading data on my network). And then I read on Panbo that someone thinks that the rate gyro on the Airmar is used to correct the apparent wind data. Not just to correct the compass, in order to improve heading data, and thus to improve true wind data, which the Airmar calculates itself, unlike the Maretron, which outputs only apparent wind, like a regular old-fashioned wind transducer.

WTF? If this is true, then the apparent wind data will be much better from the Airmar. But I don't believe it works like that. Anyone know?
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Old 16-12-2012, 14:30   #2
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Re: Maretron vs. Airmar Ultrasonic Wind

I have the Airmar but don't know the answer to your question about the rate gyro. I suspect it does have a role.

What I have observed is that the apparent wind direction doesn't change a single degree with varying heel angles or seas as you see with a standard anemometer. I don't see how this could happen without some additional sensor inputs.

I've never considered its size or weight at the masthead an issue. I don't think it's heavier or more windage than my old Raymarine anemometer

I did have to remount it for clearer air. In certain wind directions it would be off by 40 degrees. Mounting it on a 6" longer forward stalk instantly removed the problem. Another case of RTFD

Carl
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Old 16-12-2012, 14:33   #3
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Re: Maretron vs. Airmar Ultrasonic Wind

For best heading, true wind and apparent wind data the PB200 beats them all. I think the Maretron device is basically a land based device.
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Old 16-12-2012, 14:49   #4
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Re: Maretron vs. Airmar Ultrasonic Wind

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Originally Posted by DeepFrz View Post
For best heading, true wind and apparent wind data the PB200 beats them all. I think the Maretron device is basically a land based device.
Have you read any direct comparisons? The Maretron is definitely not "land based", on the contrary it is specifically a wind instrument, whereas the Airmar is primarily intended as a weather station. The Airmar manuals actually cautioned against using them as wind instruments, as they bare supposedly no accurate enough ton use with an autopilot! Users quickly laughed that off, after discovering how well the Airmar works as a wind instrument.

Our own Nick of Jedi, an electronics freak and perfectionist, chose the Maretron, figuring he had no use for the GPS and compass at the masthead.

I am guessing that the rate gyro in the Airmar does nothing more than correct the compass in classical fashion, so that the unit will output true and ground wind without getting heading and position from the network. That is so it will work as a freestanding weather station.

If that is true, then the Maretron, which is NMEA only, lighter, less windage, cheaper, simpler, is what I need. IF, however, the Airmar really does correct APPARENT wind data with the rate gyro, then I HAVE to have it! . Now I just have to figure out what the truth is. I guess I can call Airmar if all else fails.
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Old 16-12-2012, 15:22   #5
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Re: Maretron vs. Airmar Ultrasonic Wind

Looking at both spec. sheets I notice some info not spec'd on the WSO100, such as rate of turn info and error during turn. They also don't spec. the accuracy at 30 deg. tilt, they just say it works at 30 deg. I also did not see any pitch and roll accuracy for the WSO100.

By the way both units are called Weather Stations by their respective makers.

You are not going to get accurate true and apparent wind data when the mast is bouncing around in heavy weather without some kind of rate sensor input. However if you don't need that kind of accuracy then I suppose you should go for the price point and difference in weight (1.2 ozs).
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Old 16-12-2012, 15:32   #6
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Re: Maretron vs. Airmar Ultrasonic Wind

Airmar PB200 gets my vote
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Old 16-12-2012, 15:43   #7
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Re: Maretron vs. Airmar Ultrasonic Wind

Well, I've spent the last couple of (pleasant) hours reading aboutnthese sensors.

Despite many instances of Dan at Panbo claiming that the rate sensors and "sophisticated correction software" are used to correct the apparent wind data in the PB200, this is specifically denied by Airmar:

I quote " The PB200 uses a yaw rate gyro to stabilize the 3 axis heading sensor. The stable heading sensor is then used to calculate true wind. This is why the PB200 works much better than the PB150 which only has a 2 axis compass and no rate gyro. We are aware that the wind data will be more accurate if we also used pitch and roll data in the calculation, but it is not a simple value to add. We must first collect data and create a curve correction which involves many variables, including pitch, roll, wind speed and wind direction. The amount of variables made this more complicated than originally anticipated, so it was never developed for the PB200."

So apparent wind data from both Maretron and Airmar is not processed. It is damped by the instruments, however.

The fabulous performance reported by PB200 users must be the result of no inertia effects with a solid state transducer. You can imagine what kind of data you get out of a mechanical vane swinging around as the boat rolls and pitches and the mast swings around.

So so far not one shred of evidence that the Airmar gives better AWA data than the Maretron. I'll keep digging, however, my mind of course is still open.
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Old 16-12-2012, 15:50   #8
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Re: Maretron vs. Airmar Ultrasonic Wind

The quote is from: Panbo: The Marine Electronics Weblog: Sailing with an Airmar PB200 - Part II

I might add that I will have the same compass and rate gyro as is in the PB200, as I will be buying the fabulous Airmar H2183 heading sensor, and I will be installing it where it belongs - near the roll and pitch center of the boat under a settee. So if it's not used to correct AWA data, I don't need it at the masthead, where it does not work well as a heading sensor. I can brew my own true wind data on the network using much better heading data from the H2183. The supreme consideration in the wind instrument is excellent AWA and AWS data. The calculated stuff I can do in the network.
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Old 16-12-2012, 16:07   #9
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Re: Maretron vs. Airmar Ultrasonic Wind

Thanks Dockhead. I too just spent the last hour or so going over the PB200 documents as well, and came to the same conclusions, although I didn't find your specific quote.

I long ago decided to go with the Maretron when the time comes (the plate is overfull already). Putting the GPS, compass, and gyro/rate sensors at the masthead is positively daft. When I first bought a GPS in 1993 I mounted it on the stern radar pole above the scanner; roll and yaw really affected the output, and necessitated increasing the averaging time. Since then I have mounted the GPS on the house or dodger as close as possible to the center of rotation. Similarly the autopilot compass needs to be near the center of rotation for best results; these days I have a Maretron SSC200 mounted within a couple of feet of the center of rotation. With this setup, all that is needed is the Maretron WSO100 for all of the weather data I care about.

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Old 16-12-2012, 16:11   #10
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Re: Maretron vs. Airmar Ultrasonic Wind

Dockhead, I appreciate all of the research you have done with your instruments, but, as someone who is going to install a set of B&G Tritons this spring to replace my old Signets - system 1000. etc (which, by the way are still going strong) I am intrigued by your choice of the ultrasonic sensors for speed and direction. If they are so much better, why aren't the big instrument makers using them?

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Old 16-12-2012, 16:35   #11
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Re: Maretron vs. Airmar Ultrasonic Wind

Quote:
Airmar is in the process of updating their range of weatherstations. The current PB150, LB150 and PB200 will all be replaced this year by models from the new WX Series.
I just came across this. There is no information on the Airmar web site.

Blue Heron Marine
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Old 16-12-2012, 16:37   #12
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Re: Maretron vs. Airmar Ultrasonic Wind

Well, if you read the Airmar sales stuff, you will see why it's not daft to put everything in one unit - they are oriented to power boats - "PB" stands for "power boat" - and even emergency vehicles. All sensors in one unit, all calculations performed inside the unit, and you can output the comprehensive "weather" sentence which is implemented in NMEA0183. Besides that, on a power boat, the heading and GPS data will be perfectly usable.

For a sailboat with an N2K network and better GPS and heading data from elsewhere, which doesn't requre pre-processed TWA and TWS and ground wind data, I don't think it makes much sense to have all those sensors in one unit. Although I would gladly buy all the unnecessary carp just to get superior AWA and AWS data, if it provded that, but I don't think it does.

Here is yet another variant:


CV7-C is the high speed ultrasonic wind sensor. - LCJ Capteurs

Maybe best of all! Specifically for sailboats, and even for racing!! Reasonable in price! Claimed accuracy is best of any - 1%!
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Old 16-12-2012, 16:40   #13
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Re: Maretron vs. Airmar Ultrasonic Wind

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Originally Posted by DeepFrz View Post
I just came across this. There is no information on the Airmar web site.

Blue Heron Marine
I also saw it. Doesn't say in what ways they are different from the existing series - feature list is the same.
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Old 16-12-2012, 17:02   #14
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Re: Maretron vs. Airmar Ultrasonic Wind

I hope you don't mind if I hijack for a minute but I hav a related question that hopefully you'll indulge. I have a steel boat, so what's worse? putting the rate gyro in the middle of a steel box, or up high on the mast?
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Old 16-12-2012, 17:33   #15
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Re: Maretron vs. Airmar Ultrasonic Wind

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Originally Posted by Dockhead View Post
CV7-C is the high speed ultrasonic wind sensor. - LCJ Capteurs

Maybe best of all! Specifically for sailboats, and even for racing!! Reasonable in price! Claimed accuracy is best of any - 1%!
Apparently UK prices must be a bunch different than here in the US. The CV7-C is shown as 779.00. That is for an NMEA 0183 instrument that measures wind speed and direction, but not humidity or barometric pressure. To make it N2K compatible an interface box must be installed below, which adds pressure - price not stated. I do like the lightweight, compact sensor with carbon fiber mount, but without N2K and the other sensors included it is priced far too high for the US market.

The Maretron WSO100 is available for $615 in at least one store, and includes N2K and humidity/pressure. The new Airmar 110-RH is comparable, and for $779.95 (presumably list price). The US market is safe.

Greg
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