... written for Panbo by Dan Corcoran and posted on Feb 10, 2009
Many readers have commented on my Sailing with an Airmar PB200 entry. I enjoyed reading and responding to comments, and offer this diagram in response to some questions about mounting the PB200. The diagram above (click to enlarge) shows the parts unassembled, and then assembled on the masthead, along with an alternate "Plan B" my yard came up with before installation in the event my masthead was too crowded. (Credits to Jeff Willis at Willis Marine in Huntington, NY.)
The PB200 was designed to be used with marine VHF mounting hardware, like those I found at West Marine. On one end of the PB200 cable is a large two sided fitting that screws onto a standard VHF extension pole, after leading the cable thru the pole. With the fitting installed, the top of the pole then becomes a receptacle for the PB200 which is plugged in after all the other installation steps are completed.
Some things to look out for when choosing a location on your mast ... don't get too close to any masthead lights. My installation is very close to my tri-color and anchor light. As the lights are wider than the mounting pole, they are visible, but dimmer across a 10 degree arc where the pole is. It's fine, but had I used LED masthead lighting I would expect the light would have been entirely blocked across 10 degrees. I imagine this could be reduced close to zero if you can get the pole six or more inches away.
The instructions recommend a 3 foot distance from the VHF antenna (on your masthead). As my helm and nav stations is filled with electronics with such requirements that can't be meet, I have become numb to such requirements. Although I didn't have a problem, you could easily double the distance I got, by mounting as per Plan "B" in the diagram .. or attain the full 3 feet separation using a tall extension pole. Plan "B" also has the virtue of gaining additional distance from the masthead light.
The placement of the PB200 over the masthead, rather than forward or aft as you see with some top line wind sensors, provided astonishingly good results both upwind and downwind. I would highly recommend you do the same. The local birds might be unhappy, but the straight up and down installation is simple and sturdy.
I have had a Maretron WSO 100 installed on my Gozzard mast top exactly as you describe for 2 years now, with very satisfactory results.
The only difference is that I substituted a custom made base for the standard one as my mast top was not large enough to support the diameter of the standard unit.
Posted by: Bob at February 10, 2009 7:45 AM |Reply
Better mount without any significant light obstruction:
Lopolight (I know its pricey - but beautiful enough to make you want to climb the mast) has an optional top cover with incorporated 4" tall VHF mount. Aluminum and light weight.
Our mount: Lopolight topped by the optional VHF mount - 12inch Gemeco aluminum VHF mount extension tube (lighter and stiffer than Shakespeare extension) then wind sensor.
Note Airmar had a mock up - not produced yet - SB200 or something like that meaning sail boat with a mount on top for the VHF antenna.
VHF whip antenna is still an obstruction but can be at aft end of masthead or even extended a foot behind in a fairly typical install with Windex on the whip.
Note depending on your NMEA 2000 install having a compass at top of mast in addition to one in the hull produces a second string of conflicting compass information that can confuse some instruments/displays (Maretron) and not others (Simrad) - don't know about any other manufacturers.
Posted by: grandsoleil at February 10, 2009 10:04 AM |Reply
Which VHF mount did you use? The nylon one?
My mast is on the ground and I'm still doing a lot of prep work. For instance, I'm doing the drilling for a double spinnaker bail and I can do the drilling for VHF mount as well. The stainless steel version seemed pretty heavy, overkill.
Posted by: Olsonist at February 10, 2009 10:42 AM |Reply
The sailing version should have an LED tri-color and anchor light either built-in or have a mounting platform for them, instead of the GPS. It should also have an option to mount a VHF antenna on top. I think the recommended 3 foot separation assumes they are in the same horizontal plane; mounting the VHF on top should minimize interference. If the power and coax cables can't be designed to pass through, they could probably be designed to pass around in a loop at a reasonable distance so the interference with the wind sensor is minimized.
Posted by: norse at February 10, 2009 1:17 PM |Reply
Norse, thanks for jogging my thinking a little. I actually can do this today. I have the Lopolight tri/anchor LED with the VHF lid, the last one sold. So I put the Shakespeare extender on top of the Lopolight, and I now can put the PB200 on top of that with no obstruction issues at all. The VHF antenna goes aft with the Davis windex rotating on it. I'll send some pictures next week when the installation is all done.
Posted by: Olsonist at February 10, 2009 6:17 PM |Reply
Norse: I think the GPS is used internally by the unit to calculate true wind and possibly refine other data so the instrument can send those PGNs without consulting other shipboard instruments. Since you can buy bluetooth GPS receivers for $30, I don't think it adds much to the cost of the unit!
I WORRY about heat and RFI from mast head lights affecting the unit; I'ld like to hear some comforting words.
And I would really like to know what Garmin's GMI-10 can do with all that data!
Posted by: Sandy at February 11, 2009 11:03 AM |Reply
Olsonist wrote “Which VHF mount did you use? The nylon one?”
--> I went with the stainless base and polycarbonate pole. I was concerned the nylon base was subject to damage by ice during winter storage with mast up. Remember to use corrosion protection if your masthead is a different metal, like aluminum.
Sandy wrote “I WORRY about heat and RFI from mast head lights affecting the unit; I'ld like to hear some comforting words.”
--> I don’t see a problem, the PB200 is mounted 24 inches away
Wow this article captured the interest of many readers to respond … thank you all for being so engaging, this is a lot of fun for me.
I am writing this comment to clear up some confusion evident in comments regarding sensors involved in wind calculation.
For example there was confusion around true wind and which sensors were involved in calculating it that I want to dispel. For example the comments about GPS’s role in the calculation (GPS is not involved at all), some confusion about “what if’ VHF interferes with GPS would it interfere with true wind (no !), and does the GPS need to be in the PB200 to get these astonishing results (no !), or does the network move GPS information fast enough that the proximity of the GPS sensor matter.
So let me clear up the confusion about how true wind was calculated during testing. Hopefully I won’t cause any new confusion or make any mistakes doing this …
In the order I list below, is how I see the sensor information building upon each other to get the results I experienced.
Call me out if I screw up below, this true wind stuff gets tricky, but I am 97% sure this is how each of the sensors built upon each other:
1. PB200 Apparent Wind Speed and Angle = “on” and configured at 5x per second as an output to the NMEA-IN port of the Raymarine E-series. I believe the only sensors involved are the temperature and angle of heel corrected ultrasonic wind sensor, accelerometers, and motion compensation software.
Note: This was all that was used by the autopilot to steer 45 & 130 degrees off the wind, and obtain the astonishing wind readings I saw on my ST60 Wind Display, E-series chartplotter, and the amazing autopilot results I reported.
2. Next sensor up … isn’t on the PB200, but rather the paddlewheel sensor under the boat which is an input to the ST60 Tridata, which in turn outputs SOW (speed over water) onto the seatalk network to the e-series. This is needed for true wind calculation angle (as a number of degrees starboard or port from the bow) and true wind speed.
3. PB200 True Wind Speed and Angle (relative to the bow) = “off” (True Wind was instead calculated by e-series, using above sensors only).
Note: The True Wind readings that were appearing on my ST60 Wind Display, when I toggled true wind mode, used only the sensors above.
4. PB200 Compass Heading = “on” at 10x per second
Note: The E-Series then calculated the True Wind Speed and Angle (relative to magnetic north), and displayed on my e-series data window.
5. PB200 GPS Lat/Long + COG + SOG = “on” once every 2 seconds.
Note: The E-Series then calculated the Ground Wind Speed and Angle (relative to magnetic north) and displayed on my e-series data window. I have made no comments in the article about this reading, it wasn’t at all the focus of the testing, but mentioned here to highlight that the only role the GPS has in wind calculations was non existent until this step. It is an option of the PB200, in the event of a paddlewheel failure to substitute the GPS SOG for SOW, but that was not the case during testing.
I expect this explanation is going to support the point I made in an earlier comment that the compass heading and GPS sensors were not relevant to the results I experienced and the technological stars in this evaluation where the accelerometers, motion correction software, while the ultrasonic (no moving parts) wind measurements were important but secondary.
Make sense?
That’s not to say I don’t value the mast mounted PB200 compass. I did get great results and agree with Ben, that "our notion of where to put a compass may get inverted". When I get back in the water I expect I will find this will greatly improve the true wind angle (relative to magnetic north) and ground wind angle and speed reported ... measurements that in the past were so inaccurate I really didn’t give them much attention. I also expect I will find my e-series displaying better set and drift information, that can be useful in navigating the shortest distance on my longer passages.
Again, thank you all for being so engaging, this looks like one of the most commented on articles on Panbo, and it has been a lot of fun for me.
Dan
My aging ST50 instruments are sitting in a grocery bag covered with fiberglass dust, and I'm very interested in the Airmar PB200. I am very glad you've shared your positive experience with it. Where you have chosen to do true wind calculations in your tridata to send to your chartplotter, I would prefer to use all of the features of the PB200, in which case the GPS, compass, accelerometers, and motion compensation software are used by the internal processor to send true and apparent wind data as distinct PGNs or NMEA words without needing external data from the paddlewheel. This frees up the processor in the chart plotter.
The difference between using speed through the water or speed over the bottom was debated elsewhere recently and got bogged down in syntax. My simple mind is only capable of distinguishing true wind as what you feel on your face when you aren't moving, versus what you feel on the boat. The difference is the movement of the boat, which is the sum of current, crab, and progress through the water. Crab is very important to a catamaran with shoal draft keels. And its very difficult to measure.
I may have missed the answers, but I'm still wondering. Would the EMI from a Masthead LED affect the PB200? Will the compass in the PB200 provide the data rate needed for MARPA? Can a nearby VHF antenna be a problem? Do I have enough room left in the electrical conduit in my mast for yet another cable and plug? Who is going to win the Belmont?
Posted by: Sandy at February 13, 2009 1:32 PM |Reply
Sandy wrote "I am very glad you've shared your positive experience with it."
>> Your welcome!
Sandy wrote "Where you have chosen to do true wind calculations in your tridata to send to your chartplotter"
>> The tridata provides a SOW source to the e-series chartplotter, the charplotter does the true wind calculation.
Sandy asked "Would the EMI from a Masthead LED affect the PB200?"
> Don't know. Not apparent to me why there would be a concern.
Sandy asked "Will the compass in the PB200 provide the data rate needed for MARPA?"
> Yes, meets the 10hz data rate that most people use, and worked well with MARPA on e-series.
Sandy asked "Can a nearby VHF antenna be a problem?"
> Don't know. Not apparent to me why there would be a concern. Should it be, disable the compass and GPS, the other sensors are what give the astonishing wind results, the compass and GPS already exist on most our boats already.
Sandy asked "Do I have enough room left in the electrical conduit in my mast for yet another cable and plug?"
> How to tell ? The way my yard passes the cable thru the deck, to minimize the size of the penetration, the plug needed to come off anyhow and be spliced back on. I used the fat cable that supports NMEA-0183 and NMEA-2000 simultaneously. If I was just using NMEA-2000, I would have run the thin NMEA-2000 cable up the mast and made the connection at either the masthead or the mid-mast radar mount instead.
I (Dan) wrote "I used the fat cable that supports NMEA-0183 and NMEA-2000 simultaneously"
>> BTW: I didn't do this for redundancy, rather I was also evaluting the WeatherCaster PC software which hasn't yet been released for N2K. That I can evaluate next on N2K with the same cable is very cool.
Thanks Dan.
The EMI concerns originated from some reports of interference from LEDs at SSCA.
All lights generate some heat which would affect the tiny variations in wind velocity between the ultrasonics. I'm sure that this effect was considered, and some precautions were developed, but I have a very busy masthead; it ain't pretty up there.
Posted by: Sandy at February 15, 2009 12:35 PM |Reply
Thanks, Dan, for all the info on the PB200. I've been anxiously awaiting its availability since replacing my other (dead) sailing instruments with N2K models last spring.
I suppose the coments concerning RFI, data rates, mounting options, and the subtleties of 3-axis accelerometer corrections are appropriate for a propeller-head forum like Panbo (sorry, Ben). But what I'd REALLY like to hear is more information on its performance while sailing to help tease out puffs and wind shifts. (I mean, BOATING is the ultimate objective, after all.)
Dan, your description of the PB200's excellent performance in autopilot-assisted sailing was very useful. From the description, I imagined that your "steady winds" were somewhat over 10 knots upwind. Have you been able to suss out its performance in lighter air yet? In particular, the PB specs suggest less accuracy in winds under 10 knots. Does this manifest itself when the wind drops, e.g. resulting in increased variability of readings that are not damped out?
Perhaps when you get some round the buoys experience this spring you can provide us with a "Sailing with an Airmar--Part III"!
Posted by: JCS at February 25, 2009 2:13 AM |Reply
JCS - Yes, all the on the water tests were above 10 knots true, with apparent wind higher or lower depending on my course. The lowest apparent wind my autopilot was steering in was 6 knots.
I look forward to reporting more on the water experiences in Spring.
JCS askes “Have you been able to suss out its performance in lighter air yet?”
-->With the autopilot no, but at the dock I gained some clues. At the lowest speed I observed (around 2-3 knots) at the dock the PB200 gave me a wind angle I could still believe in (keep in mind I had no way to judge wind accuracy better than say +/- 20 degrees). Both appeared to do fine as long as my boat held steady, when the mast sways or the wind changes direction … no matter the wind speed, a performance difference in reporting wind angle opens up. The PB200 steadfastly held to the reported wind direction even as the mast swayed from the small wakes of passing boats in the nearby 5mph zone, where the mechanical vane and ST60 combination errantly reported a wind angle change.
JCS wrote “In particular, the PB specs suggest less accuracy in winds under 10 knots. Does this manifest itself when the wind drops, e.g. resulting in increased variability of readings that are not damped out?”
-- > It came as a surprise to me, when testing at the dock that I would see a difference between the mechanical vane and PB200 … as I am in a 5 mph no wake zone, and thought the ST60 damping function would be entirely effective. I even dragged 100’s of feet of old line from home in preparation for testing ... to induce a bigger mast movement, but it turned out unnecessary.
It didn't take much mast shake to see that the wind angle readings were effecting the mechanical vane and not the PB200.
As a result of this surprise, I spent multiple visits at the dock attempting to find a better damping value for my ST60 / wind vane combination to see maybe if I could close the performance gap with the PB200 when the mast is swaying, and in doing so tried different values for the ST60 connected to my PB200 as well.
I became comfortable with the ST60 connected to the PB200 being set at the lowest damping setting, I continued to see a smooth tracking between the observed movement of the wind vanes and the ST60 display, and got quicker response times as a benefit of the low damping value. I have not tried this low damping value on the water … I’ll do that in the Spring, but in any event the autopilot wouldn’t be effected … it gets the un dampened wind direction right from the PB200 across the seatalk network. I later learned the PB200 WeatherCaster PC software has a damping configuration setting also … I did not experiment with it.
I also came to believe the damping setting Raymarine uses as default for the mechanical sensor is correct. It just doesn’t dampen out as much as I had believed all these years. I am guessing the rather low period of the mast swing limits how much damping can be applied before users become fustrated with the readings being delayed.
Thanks again, Dan, for sharing your experience. It's been my experience, too, with mechanical sensors in light air that lateral motions at the masthead introduce transitory variations in wind angle readings that one eventually learns to discount. It requires patience and experience (not to mention reliable short term memory) to discern a subtle but persistent wind shift. (Which ability, as they say, is worth thousands of dollars in go-fast sails!)
It certainly seems to me that sophisticated error-correcting algorithms as exemplified in the PB200 have the potential of dramatically improving wind instrumentation for sailors. And with Ben's report of a forthcoming 3-axis rate gyro in the PB series, Airmar is evidently not resting on it laurels!
Posted by: JCS at February 27, 2009 3:46 PM |Reply
My tax refund just covers a PB200. Providence has spoken.
The PB200 is easily my most favorite addition to the marine electronics on Breeze Pleeze, and won't need much prompting to write more about it.
I am unsure if Part III will be about converting over to NMEA-2000 (see post today about the new network on Breeze Pleeze), more experience on the water, or a visit planned by Airmar to come aboard Breeze Pleeze on a day with especially turbulent weather and seas with some fancy equipment to help measure and report on performance in some depth.
Never had the visit, in the time frame we were aiming in May/June 2009 we couldn't find a single day with the big seas and wind to perform our planned test.
This is my favorite marine instrument, I should write some more about it and include a video I took that captures the stability of the wind measurement of the mast motion corrected PB200 vs the uncorrected cup and vane sensor.
To answer an old question, the Garmin GMI10 recognized the PB200 out of the box, and displayed apparent and true wind direction and velocity, barometric pressure and trend, compass heading and more just peachy keen! I'm running the Airmar software on my boat PC thru their gateway, and displaying the data on both chart plotters. I expect Garmin's most recent update will clear up some issues I have that relate to too many sensors, a mix of old and new processors, and two flavors of NMEA colliding. If I can get away from this computer, I'll get my new DST 800 installed today, giving me depth, speed and water temp on N2K. Then another venerable ST50 instrument will find a place in the too-precious-to-throw-away box.
Posted by: Sandy Daugherty at March 24, 2010 12:11 PM |Reply
Nicely written piece. Keep up the good job you're doing.
Thank you very much for your info. I am considering the PB200 in combination with Garmin network/NMEA2000 and a Simrad autopilot.
Do you get VMG to wind in any way?
Posted by: Erik Dammen at May 25, 2010 2:42 PM |Reply
We have installed a PB200 on a 60' mast aboard a one-tonner getting ready for the Vic Maui race. Wind and compass readings are very steady even in rough conditions.
The system is NMEA 2000 with an onboard computer and touch screen display running Avia Sail (disclosure--I'm the developer of that product) and Coastal Explorer (getting translated NMEA 0183 from Avia Sail).
The VHF antenna is much less than 3' from the PB200. We have an AIS receiver but no transmitter. When transmitting on the VHF the GPS numbers from the airmar go crazy. This caused Coastal Explorer to lock up. We fixed it by changing the software to ignore latitudes over 180 degrees and speeds over 200 knots.
However before doing that we set a new sailboat speed record. 1274 knots in only 5200 knots of wind!!!
Avia Sail, Coastal Explorer, and the VHF (which also locked up due to the GPS data) now behave fine. You can try a demo copy at http://www.aviasail.com.
We have not tried the heading output with the autopilot yet. Our Raymarine X-10 autopilot also has a gyro so I'm not sure how that will work.
Posted by: yacht371 at June 10, 2010 12:05 AM |Reply
Thanks for the report, Grahame. I have heard vague mentions of VHF transmission bollixing the PB200 if too close, and also the PB200 causing some VHF interference, but I've never tried to reproduce the situation. Hopefully some other boaters who have mounted VHF and PB200 close by will report in.
I did manage to inadvertently test the sensor when mounted about six feet from, and nearly level with, a 4kw radar. It made the GPS position jump around alarmingly but didn't seem to effect the heading or wind measurements. Please report again during or after the race. Some screen shots of Avia Sail in action would be good too.
I am very keenly following this thread and I am grateful to all contributors. I have an advantage of starting a nav system from scratch and plan to use the PB200 on a 48' cat running a nmea 2000 network from the top of the mast and connecting a Box PC to the network as a base line. I am having a T bar made up to separate the VHF aerial from the PB200 at thye top of the mast which will leave the tri unit safely in the middle. I will use a stand alone radar with a connection to the network and hope to overlay the nav software as well. Looking at open CPN or Maxsea at the moment. I will continue to get help from this very useful discussion, any comments will be gratefully received!! Many thanks
Posted by: Barry Davenport at August 20, 2010 8:09 PM |Reply
I have a PB200 on my Alerion Express 33, which was mounted with the wrong cable initially, and became intermittent almost immediately. I finally got that fixed with a factory-fresh AirMar 100' sensor cable, trimmed to length. Make sure you use this heavy duty cable!! These long cables have the NMEA2000 terminator embedded in the cable, making it easy to end your network at the masthead. The installer initially had a tee connector and terminator up on the mast-- not tidy. My revised installation is now working very well; it is an amazing product!
Concerning VHF interference: I have a Garmin VHF300 AIS, and it DOES pick up audible interference from the PB200. The VFH antenna is just a few inches to the side of the PB200. The interference comes n the form of an increased level of white noise in the background of transmissions, as well as a sharp clicking sound at about 3-5 Hz. When the PB200 is unplugged, the interference goes away. When it is plugged back in, the static comes back immediately, and then the rhythmic clicking about 2 seconds later (wind sensor starting up??).
When repairing the cable yesterday, I had the rigger in the bosun's chair hold the PB200 at varying distances away from the VHF whip. We found that increasing separation to only about 8-12" audibly eliminates the interference. As Barry D. above is planning, we will now put the VHF antenna on an 8" stand-off to the port side of the masthead.
Posted by: Vincent Argiro at October 8, 2010 3:42 PM |Reply
Vicent, did you mean you used the optional NMEA-2000 terminator embedded in the PB200, selectable by inserting the little gold pin in one of the pins of the socket ?
Dan, Airmar had to change the termination scheme to get NMEA 2000 certification. It was supposedly because the pin system made it impossible to tell visually if there was termination or not, but I don't understand how termination built into the cable is different. At any rate, Furuno's recently released version of the PB200 reverts to the original design, and is uncertified "CANbus"...kind of a flip off to NMEA ;-)
If you look on Page 16 of the AirMar manual for the PB200 (airmartechnology.com/uploads/installguide/PB200UserManual.pdf), at the bottom of the page you will see the spec for the long cable with termination, and the note that all of their cables longer than 20 ft have the terminator.
Ben, AirMar LABELS the cable something like "sensor connector contains terminator" near their connector. So I guess that qualifies as visually distinguishable for the certification. Bottom line, it is a MUCH better way to install one of these on a masthead!
Best,
Vincent
Posted by: Vincent Argiro at October 8, 2010 9:03 PM |Reply
Dan / Ben:
Here's how we are going to mount a PB200 on top of our Lopolight setup:
I purchased a PB200 right after the change from an internal resistor to one in the cable. (Had a wait a bit as the cables weren't even ordered by Airmar yet.)
Airmar sent me a cable with the label stating it had the resistor installed. I have my doubts. The error count on my network shot up and I eventually tried an inline resistor at the base of the mast.
Probably not optimal, but everything works.
Just my opinion, but resistors in hard to replace cables--like this installed in a mast--are a very bad idea.
But I do like the reading I get from the PB200. (Mast height is around 70')
Posted by: Jeremy Anwyl at October 10, 2010 11:38 AM |Reply
Hi Guys,
Here is some comments regarding the PB150 and most of it is relevant to the PB200 as well. This is a revised letter I sent to Airmar and I list a few questions I am currently trying to figure out. I am hoping Airmar will answer but in the meantime any comment / answer is much appreciated here on Panbo.
Setup:
I chose the PB150 because I don’t use NMEA 2000, and I already have a rate gyro compass with my Furuno autopilot so I didn’t feel I needed to pay extra to get the 3-axis compass found in the PB200.
I mounted the PB150 on a 35cm high extended VHF base next to the navlight on the masthead (16m mast) and it sits approx 50 cm from the VHF antenna.
I use an Actisense NDC-4-USB NMEA data multiplexer (I think Actisense actually make the Airmar NMEA 0183 combiner). Using the Actisense I am successfully connecting my PC to the PB150 using the WeatherCaster software.
I use a Wind-a S400 wind meter from AdvanSea/Plastimo.
I also have a Furuno RD30 display, Furuno 1724c chartplotter, Furuno Navpilot 510, and Furuno PG500 Rate Gyro.
Feedback, Comments, and Questions:
PB150 / GPS receiver
When installed at the masthead on a sailing yacht the GPS receiver in the PB150 is not very useful. When the yacht is en route the receiver is constantly in a pendulum motion which results in the SOG and COG figures to fluctuate far too much to be of any use for navigation by a chart plotter.
I was surprised the GPS performed so poorly (even on a flat calm day with the boat just gently rocking on some small ripples) so I took out my handheld Garmin GPS to compare figures. If I held the Garmin in my hand it would give a very stable SOG and COG, but if I just slowly moved my hand left and right and back and forth (and I really mean slowly and gently) the figures started to exceed a variation of +/- 1 knot and +/- 5 degrees. This is a very simple test that anyone can do. It makes me think that many sailing boats out there with a GPS antenna mounted on a rear solar panel arch with a VHF extension pole will not have a very stable SOG and COG.
The Airmar software does not allow changing any settings for the GPS receiver such as position smoothing (smoothing coefficient) and spd/cse smoothing (dynamic coefficient) as with for example a Furuno GP-320B.
Question: Does WAAS or no WAAS make any difference in the smoothness of the SOG and COG calculations?
Question: Does the GPS receiver have a built-in magnetic variation table?
Question/Suggestion: Can a correction algorithm using pitch/roll from the 3-axis accelerometer (similar to what is done with the apparent wind speed and angle) be applied to the SOG and COG figures?
Suggestion: Can the firmware be modified to disable the GPS receiver so that it does not use any power and possibly interfere with the VHF antenna for those boats that prefer to use an external GPS receiver?
PB150 / 2-axis Compass (heading sensor)
The manual for the PB150 states that the internal 2-axis compass is not good enough for a reliable heading and that the internal COG should be used instead. Following my discussion above I don’t think that would help much and it seems to me that the only reliable calculation is using the HDG from another properly (as close to the centre of gravity as possible) mounted Rate Gyro.
Question: What is the compass used for apart from getting the heading for true wind calculations?
Suggestion: Can the firmware be modified to disable the compass so that it does not use any power and possibly interfere with the VHF antenna for those boats that prefer to use another heading sensor?
Suggestion: Could the WeatherCaster manual describe how to best adjust the compass damping coefficient?
PB150 / 3-axis Accelerometer
Question: Read on panbo.com “The PB200 differentiates itself from past versions and competing mast head sensors by incorporating a 3-axis accelerometer and internal motion correction software able to measure and correct for the motion of the boat bouncing underneath it.” Does this apply to the PB150 as well?
Suggestion: Could the WeatherCaster manual describe how to best adjust the pitch/roll damping coefficient?
PB150 / Wind and meteorological sensors
Question: The Furuno WS200 manual says; “NOTE: Do not use wind data in the WIND mode of an autopilot, because the data is not sufficiently accurate.” This seems surprising as the apparent wind figures taken from a sensor with no moving parts and corrected for pitch/roll are quite likely to be far more reliable than those taken from a traditional mechanical wind vane. Can you explain why it is not advisable to use the data with the autopilot?
True Wind Speed and Direction
I have tried to get my head around the true wind calculation as it is not totally clear in the manual and here is what I have come up with.
To calculate the true wind we need to know the speed and possibly the direction of the boat:
The speed of the boat
* Needed for true wind relative to the bow
* Needed for true wind relative to the compass
SOG from a GPS (VTG or RMC)
If no external VTG/RMC signal is present the PB150 will use the SOG as calculated by the internal GPS sensor.
PB150 can also calculate the true wind relative to the boat speed through water using an external VHW sentence. The assumption is then always made that the course and heading is the same and the true wind calculation is relative to the bow.
The direction of the boat
* Needed to true wind relative to the compass
HDG from a compass
If no external HDG signal is present the PB150 will use the HDG as calculated by the internal compass.
However it can also be configured to use the COG as supplied from a GPS (VTG or RMC). The external value will be used if present, else the internal GPS sensor is used.
Question: Am I correct in assuming that only the SOG is needed for true wind relative to the bow?
VHF interference
My VHF antenna is approx 50cm from the PB150 and I have noticed interference in the form of a ticking background signal when receiving VHF calls, and fellow sailors commenting about a background noise when I transmit using the VHF. The manual states that the VHF antenna should be at least 1m away but that is rarely if ever possible on a masthead. Is this something Airmar is investigating and do you have any comments on this?
My conclusion regarding PB150 on a sailing yacht
The internal GPS does not supply smooth SOG/COG figures at the top of a mast, but when an external GPS is present in the NMEA string it is not used anyway.
When viewing true wind relative to the bow of the boat only the speed of the boat is needed (SOG or STW). SOG is reliably supplied by an external GPS (VTG or RMC).
The internal compass is 2-axis only but it not really needed if you are only interested in the true wind relative to the bow, and if you want it relative to north the best option is to use an external Rate Gyro (HDG).
As a wind sensor only on a sailing yacht the PB150 seems to perform better than any mechanical wind sensor currently available. It also offers a backup GPS, barometric pressure, and air temperature.
One issue for sailing yacht is that the PB150 does interfere with the VHF signal when mounted less that a meter from the VHF antenna. It is difficult to mount them that far apart at the masthead.
Posted by: Sybaris at December 20, 2010 11:02 AM |Reply
A few comments, Sybaris:
* The PB200 does have more motion sensors than the PB150.
* The PB stands for "Power Boat"; Airmar has never marketed either of these multi sensors for installation on top of sailboat masts.
* However, Dan Corcoran, who wrote this and the proceeding PB200 entry has had good results using its wind angle data for his autopilot:
Posted by: Ben in reply to Sybaris at December 20, 2010 11:46 AM |Reply
Sybaris, please keep us posted about any response from Airmar, especially reagarding:
- ability to disable the internal GPS
- ability to disable the internal compass
- which part of the PB150/PB200 is causing the ticking noise on the VHF (GPS, compass, wind instrument)?
- if I invest significant effort and money to keep 1 meter distance between the VHF antenna and the PB150/PB200 at the masthead, can I be sure to have no problem with interference?
Posted by: Henning at December 22, 2010 8:13 AM |Reply
Dan do you have any update on your Part III posting? I am moving forward with I believe the Furuno WS 200, and am eager to hear about your next update for sailboats. :)
Posted by: Mark at January 28, 2011 1:14 PM |Reply
In the latest PB150 technical manual, there is a very small but interesting revision: Under received sentences, it now shows the PB150 as accepting HDG and HDT sentences, in addition to VHW and various proprietary commands.
It further states the external heading signals will supercede the internal compass. To me this implies that an autopilot or other fluxgate located in the cabin could send a signal to the masthead that would be far less sensitive to heeling errors, and I'm going to try it as soon as my boat is back in the water this Spring.
Backstory: The original PB100 accepted both external heading and GPS signals--which superceded the internal GPS and compass--to provide greater accuracy.
Thank you for your interest, it will move Part III along sooner. Part III includes a video illustrating the stark difference in Apparent Wind Angle display I enjoy with the motion correction feature of the PB200 in choppy seas.
I do first have to sort some stuff out with the loss of 1/2 our home in a fire and write also about some neat gear I tested on the water during a great season of sailing that included a sail to Camden (and a special visit to Gizmo).
There may also be something to write about in regards to some gear that still operates post (home) fire, despite heat, corrosive smoke and water damage.
Until then your welcome to contact me offline about the PB200.
My experience with the similar Airmar H2183 is that the autocalibration routine usually don't work very well and that a custom calibration is more than desirable. See my report here:
sailboatinstruments.blogspot.com/2011/01/gyro-compass-calibration.html
Posted by: Merlin at February 2, 2011 9:13 AM |Reply
So how do you program the deviation into the H2183?
Posted by: Donald Joyce in reply to Merlin at February 4, 2011 10:31 AM |Reply
Merlin seems to be adding his calibrations to a custom microcontroller that he's built his instrument system around. Not for the faint hearted!
In the system that I describe, the deviation correction is applied after reading the H2183, before using the heading value in the calculations and sending it to the display. You cannot actually program your own deviation curve in the H2183, but it would be nice to be able to enter your own deviation coefficients (A,B,C,D,E). A revision to the H2183 firmware and to the WeatherCaster software could do the trick.
I have been sailing in the Red Sea for three months now with the Airmar PB150 installed at our masthead and here is my updated feedback.
Wind sensor
As a wind sensor, on a sailing yacht, the PB150 is absolutely brilliant. It certainly performs much better than any mechanical wind sensor I have ever used. The internal 3-axis accelerometer does a fantastic job at smoothing out the apparent wind readings even in heavy seas with the mast moving extensively.
Look at this short video clip to see how stable the reading is while sailing downwind in about 20 knots of true wind.
The internal GPS receiver does not supply smooth SOG/COG figures and being at he top of a mast might make it even worse, but when an external GPS is present it takes priority anyway. Having said that, I have found that all GPS readings need to be smoothed or averaged on a moving boat regardless of where the antenna is positioned. You can run a test yourself by laying a handheld GPS next to you while sailing and looking at its reported SOG and COG. The internal GPS receiver is however very useful as a backup.
Look at this short video clip to see the SOG and COG on my Furuno chartplotter when I use the PB150 as my GPS source and you will agree that the readings are not useful for navigation.
It would be great if Airmar could use the 3-axis accelerometer to smoothen out the SOG and COG as it does with the wind readings but I don’t know if that is possible. It would be interesting to know if that is done on the PB200.
Compass
The internal compass on the PB150 is 2-axis only. However the compass is not needed at all if you are only interested in the true wind relative to the bow. If you want true wind relative to north (to simulate a fixed weather station while on the way) your best option is to use an external Rate Gyro (HDG) installed low and central in the boat. The PB200 does have a 3-axis compass but as it is positioned at the masthead I don’t think it will be as precise as a separate and properly installed rate gyro anyway.
VHF interference
There have been some comments about VHF interference caused by the PB150/PB200 being installed at the masthead very close to the VHF antenna. Having used the VHF/PB150 combination daily at sea for about 3 months now, I cannot report any interference. I think my earlier recorded problems might have been due to the proximity of large land based relay antennas.
Summary
My PB150 is connected to a Advansea S400 wind display. The PB150 supplies excellent apparent wind figures via the NMEA interface and the S400 calculates its own true wind speed/direction using the apparent wind supplied by the PB150 and the SOG supplied by my Furuno GPS.
Apart from being a wind sensor it also offers a backup GPS signal, barometric pressure, and air temperature. It is easy to install and it is not damaged by large birds (a common problem in the Red Sea with numerous ospreys).
My assessment is that the PB150 works very well as a superior wind sensor on sailing boats.
Posted by: Sybaris at March 11, 2011 6:30 AM |Reply
This article is by far the most active and helpful discussion on the web regarding ultrasonic wind instruments. Unfortunately, it has been dead for over a year! Where are all the reports from early adopters? Where is all the real world feedback?
Oh, and when will the price start to come down?
Harry
Posted by: sailingharry at April 4, 2012 6:58 PM |Reply
The magic of ultrasonic wind instruments has not been fully dissected for us consumers. BUT...the maritime meteorologists have long abandoned vanes for ultrasonic sensors. They have detailed technical analysis of the behavior of vanes and ultrasonics pitching and rolling and are opting everywhere for ultrasonics.
That being said, there are serious errors in our understanding of the two primary ultrasonic wind instruments sold in the USA - Airmar PB200 and Maretron. They do seem to output "better?" wind data i.e. smoother but it is not because of smart processing.
Airmar's unit specifically does not correct for pitch and roll - but it seems there is less artifact due to pitch and roll. I have used ultrasonic sensors since 2008 (more to follow in another thread).
Maretron's unit is simpler - but has a slightly different geometry to its slot.
I think both ultrasonic sensors contribute to a smoother autopilot performance when steering to wind direction in a quartering sea. I think a unit correcting for pitch and roll (the B&G and NKE's process in their computer at much greater $ cost) probably perform better - but the jury is out.
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."
Here is hoping a PB300 brings pitch and roll corrections to the masses!
Posted by: grandsoleil at May 6, 2012 2:23 PM |Reply
I have used a PB200 at my mast top for this season. Before ordering, I tried to get answers to a number of questions from Airmar but never got a reply. I ordered anyway and found out the (not so) hard way.
These are the questions and my own answers to them:
1. Can I use an Actisense NGT-1 USB that I already own to configure the PB200 and update it's firmware with the Weather Caster software and avoid having to purchase a separate adpater from you just for this?
Yes, I configured the PB200 as well as updated it's firmware using Weathercaster with my Actisense NGT-1 USB.
2. Can I permanently disable the compass in the PB200 (I have a H2183 much better located for stable heading)?
I don't think that it can actually be disabled but it's output on the N2K bus can be disabled (which is almost the same thing) by setting the update frequency to zero in Weathercaster.
3. Can I permanently disable the GPS in the PB200 (I have multiple GPS outputting NMEA2000 and NMEA0183 with antennas at deck level, better suited for stable COG and SOG)?
same as 2.
This is a very important feature for me, at least at the moment, because Coastal Explorer, which I use as my only chart plotter, does not have a provision to filter sources coming in on the same port. It has a full set of methods to select which GPS to use but these are per port, assuming that there is no more than one GPS on each port. As the NGT-1 and therefore the whole NMEA2000-data is considered a single port, I get a jumping boat and jumping predictor line. Actually, I still have this problem because a Simrad NSS7 that I have and use for several functions other than chart plotting has an internal GPS that can't be disabled. I am fighting that problem by having covered the whole back of the NSS7 with a triple layer of aluminum foil to prevent it from getting a fix but this only works most of the time (I can't quite cover the front, too). My Simrad AC12/AP24 autopilot has no problem because it allows to select the GPS to use and, ironically, neither has the NSS7. It happily ignores it's own rotten fixes and uses those of my Simrad GS15.
So at least I don't have to cover the PB200 at the mast top with aluminum foil ;-)
4. What should I aim for when locating the PB200 re:
- horizontal distance from the VHF antenna(s)
- vertical distance from the VHF antenna(s)
- positioning forward of the mast for accurate wind direction and speed
This was triggered by reports of a ticking noise in the VHF caused by the PB200. I put the PB200 on a horizontal pole extending about 60 centimetres (2 feet) forward of the mast, giving me clearance from the VHF antennas of abount 80 centimetres, less than the 1 metre mandated in the installation guide. I have no ticking noise and no sort of interference between anything at the mast top.
5. Running the PB200 cable up the mast is a significant job. I have read about cable related problems with the PB200 (such as here: http://www.panbo.com/archives/2011/01/nmea_2000_bridges_2_jeremys_experiments.html). If I find mid season that the cable is faulty, then, if I were to contract the job, it will cost way more than the PB200 to replace the cable as this requires unstepping and stepping the mast and retuning the rig.
What can I do to avoid any cable related problems with the PB200?
I used the regular combined NMEA2000 and NMEA0183 cable that is available im 30 meter length. After ordering the wrong one first, the second cable had a reassuring blck shrink-tube-sign near the connector saying something like "this connector has internal termination resistor". To protect the exposed cable from the sun and weather, I covered the exposed part with black heat shrink tubing. So far, all is well. I had the PB200 fail suddenly one time this season (updates on all data stopped). My heart sank when I noticed it, fearing a cable-related problem. It would'n come back up after I power-cycled it. But the next morning, all was well again and I never had another problem since. The was a thunderstorm approaching when it stopped. Could that have been the reason?
6. I would like to position the breakout box at the nav station rather than below deck near the maststep. Do you recommend this? Can I open the combined cable at the maststep to include connectors to make unstepping the mast easier?
I ended up not using the supplied breakout box because of space constraints and broke the cable open at the mast step below deck. I have used screw terminals and this has given me no problem.
Posted by: Henning at September 14, 2012 3:20 PM |Reply
Hi Henning,
Thanks for the update on your PB200.
Any tricks to using the Weathercaster s/w through the NGT-1 rather than Airmar's gateway? I have both but would really only like 1 connected.
We've had our PB200 installed for about 18 months now, but haven't done a lot of sailing in that time: about 600nm.
The boat's been out of the water for the past 6 months under-going an extensive internal refit (new galley, chart table, saloon remodelling,......, and a rewire using BEP's C-Zone distributed N2K power network which I am going to install over the next 2 months now that the carpentry has finished).
We found the PB200 to be excellent, and loved that it plays nicely on the N2K network.
We struggled a bit at first with getting the calculated true wind to display regularly on our Maretron DSM250 displays, but with the help of some of the posts and forums here, figured out that it was a data source issue - both the PB200 and the DSM250 were doing the calculation. We disabled the PB200 true wind broadcast, and that seemed to work.
We also found the heading data was sometimes a bit odd (bounced around), but again that was traced to a data input conflict and just took defining what we wanted displayed to clear it up.
We're going to float the boat again towards the end of the year, so I'll post an update once we have everything back together.
Cheers,
Paul.
Posted by: Taniwha at September 15, 2012 8:52 PM |Reply
Paul:
I have the NGT-1 talking to Weathercaster - no tricks required as I recall.
Regards,
Ted A
s/v Little Wing
Posted by: Ted Arisaka in reply to Taniwha at September 15, 2012 10:37 PM |Reply
Thanks Ted. I'll try it when we power up next (currently there's no wiring or power on the boat at all as we stripped it all out - huge job).
Cheers,
Paul.
Posted by: Taniwha at September 16, 2012 12:40 AM |Reply
re the NGT-1: same here; it works straightforward with Weathercaster. It appears in a dropdown to select the device to use.
Posted by: Henning at September 16, 2012 8:42 AM |Reply
Please note that Airmars N2K to USB interface actually is a version of the Actisense gateway.
Posted by: Don Joyce at September 16, 2012 10:27 AM |Reply
Airmar has replaced the PB200 with the WS-200WX. The specs are mostly the same. The GPS goes from 1 Hz to 10 Hz, the power supply goes from 9-16 V to 9-40 V, with 50% less current draw. The specs don't give the N2K LEN value, but it should now be 2. It goes from having a 1 axis rate gyro to having a 3 axis rate gyro. http://www.airmartechnology.com/uploads/Brochures/WX%20Series%206%20page%20Brochure%20FINAL%20printer.pdf
Posted by: norse at December 4, 2012 8:15 PM |Reply
Interesting development - I see that they also have versions with a heater in them for cold weather.
It'd be nice to know how much the 3-axis actually improves the data from the PB200 - anyone want to buy one to mount along-side their PB200? :)
The other big question is whether they use the same cable as the PB200. If anyone upgrades, it'd be a pain to have to run another cable. Anyone know the answer to that?
Cheers,
Paul.
Posted by: Taniwha at December 4, 2012 10:24 PM |Reply
The installation manuals for the Airmar weather instruments (old and new) and Airmar heading sensors specify the same cable part numbers for all, with the exception of the weather instruments with heaters.
Posted by: norse in reply to Taniwha at December 7, 2012 1:51 PM |Reply
Ben,
I have had a Maretron WSO 100 installed on my Gozzard mast top exactly as you describe for 2 years now, with very satisfactory results.
The only difference is that I substituted a custom made base for the standard one as my mast top was not large enough to support the diameter of the standard unit.