Valid True Wind Data

[Dockhead]

The holy grail of sailboat instrumentation?


Now that my CV7 wind instrument has failed -- well, not the instrument itself, but the N2K interface which I stupidly put at the top of my 75 foot mast -- I have a blank slate upon which to draw.


Is the B&G mechanical racing transducer with its 1.8 meter high or whatever wand, plus H5000 computer, plus carefully calulated speed log, the only reasonable way to solve this?


Is there really no other way?

[Tehani]

The theoretical maximum length for an RS422, which is the NMEA0183 standard, is 3,900ft, so 75ft is a safe distance.
The output of your CV7 complies with this RS422 standard, and also, at a very low speed of 4,800 baud, so it is even more reliable.

You can put your NMEA0183 to NMEA2000 converter inside the cabin.

Furthermore, the maximum length between a "T" and a device within the NMEA2000 network is 20ft., That is why all manufacturers of wind transducers use the main cable of that network to reach the top of the mast and incorporate a terminator (120 ohm resistance) there.

[mlydon]

Raymarine makes a gizmo called an itc5, which takes analog wind, depth, and speed transducers and outputs their values in nmea2000. So you can use (relatively) cheap transducers, and interface them with whatever nav system you want....
Matt

[Tehani]

Originally Posted by mlydon

Raymarine makes a gizmo called an itc5, which takes analog wind, depth, and speed transducers and outputs their values in nmea2000. So you can use (relatively) cheap transducers, and interface them with whatever nav system you want....
Matt

This device itc5 only works for Raymarine i70 ST70 and ST70+ series transducers.

[mlydon]

Not true at all - I have a generic airman paddle wheel and depth sensor - (I do happen to have a raymarine wind transducer at the moment). The same tranducers are re-labeled by Lawrence, raymarine, etc. , with their proprietary plugs. Buying the transducers bare-wire, and converting to nmea2000 saves considerable bucks - a n2k depth transducer is usually around $200 for a ‘smart’ n2k version, whereas the same in analog is less than $100. ). The itc converts the pulses from the transducers into native nmea2000 sentences that can then be used by any equipment that understands nmea2000.

[Tehani]

Mr. Dockhead has stated his specific problem. I focus on proposing a solution to this problem, using the CV7 that is in good condition, with minimal investment and complications.

Of course the paddle wheels give a pulse train, but they are not always electrically compatible, nor do they all have the same amount of magnets in the paddles, so the speed can differ significantly. Nor do the depth transducers all work at the same frequency ...

Surely you have been lucky and these two transducers have worked for you with the itc5, but you have not mentioned that you will use it for a generic wind transducer. This case is somewhat more complex, and I prefer not to go into details because I do not think it is a topic for this thread.

In any case, I think it is risky to propose the use of this device in a generic way. And surely, it would be a good topic for another thread.

[Dockhead]

Originally Posted by Tehani

Mr. Dockhead has stated his specific problem. I focus on proposing a solution to this problem, using the CV7 that is in good condition, with minimal investment and complications.
. . .

I will replace the CV7 in any case. If with another CV7, then the tall racing one with the higher data rate.

So far the candidates are that and the tall b&g racing one.

[Tehani]

I think that a wind sensor is never accurate enough in real time. Think of the linear speeds that the masthead reaches with the pitch and roll produced by the waves.
And it is also not useful from the point of view of human perception.

All this makes it necessary to apply an averaging of the sensor readings, more or less strong, to be able to present somewhat stable data in the instruments.
Sensor data is sent to the N2k and Seatalk buses without averaging. The advantage of N2k is that they are sent 10 times per second and the averaging is more accurate. (I apply an exponential average).

[dfelsent]

I went through the exercise of calibrating a masthead wind sensor. For true wind speed.
You need to calibrate at a wide range of wind speeds and wind angles and heel angles and get that data into your B&G. Oh yes and reefing will change the updraft so you may need multiple data sets.
Hours of time over weeks or months of on and off data collection.
And even then it will not be quite right. Better, yes.
Oh, and your knot meter has to be correct first, and stay correct.
For me a few data points (8) was enough. But I’m not doing it again. I found that knowing the boat well was more effective than the ballpark calibration I had.
If I was running a serious racing program I’d do the work. But I’m not !

[wingssail]

Originally Posted by Dockhead

I will replace the CV7 in any case. If with another CV7, then the tall racing one with the higher data rate.

So far the candidates are that and the tall b&g racing one.

Honestly, the B&G system, tall type 213 and H5000 with added performance processor appears to be the best there is for what you want, which is dead accurate wind information. They have been doing it for 50 years. The high end racing fleet virtually all use them.

But of course it is pricy. I helped build and commission just such a system for a new 65' carbon race boat. It cost $80,000 (just the B&G stuff).

It was awesome. But was it worth it? Well I had fun playing Navigator with it, but truthfully, no. Too much money for me. You could carefully select portions of the top of the line system and get 90% of what you are looking for for much less than that, but still carries a tall price tag.

I sense that you will decide to go that way (H5000 and type 213 and a tall mast). Just be prepared to be disappointed; they are not magic, they don't walk on water.

I have one of the oldest Hercules systems and I get pretty good true wind data from it. Not perfect. This fall, God willing. I'll install an upgraded H2000 system. The faster processors and sampling will improve the accuracy and I am looking forward to better wind info. But I am going in with my eyes wide open. There is no magic.

[Joli]

One can always consider NKE. But like others have said the gain from these systems is not something the average cruiser will notice. Race boats are not cruising boats and cruising boats are not race boats.

https://www.nke-marine-electronics.com/instruments/

[Dockhead]

Originally Posted by wingssail

Honestly, the B&G system, tall type 213 and H5000 with added performance processor appears to be the best there is for what you want, which is dead accurate wind information. They have been doing it for 50 years. The high end racing fleet virtually all use them.

But of course it is pricy. I helped build and commission just such a system for a new 65' carbon race boat. It cost $80,000 (just the B&G stuff).

It was awesome. But was it worth it? Well I had fun playing Navigator with it, but truthfully, no. Too much money for me. You could carefully select portions of the top of the line system and get 90% of what you are looking for for much less than that, but still carries a tall price tag.

I sense that you will decide to go that way (H5000 and type 213 and a tall mast). Just be prepared to be disappointed; they are not magic, they don't walk on water.

I have one of the oldest Hercules systems and I get pretty good true wind data from it. Not perfect. This fall, God willing. I'll install an upgraded H2000 system. The faster processors and sampling will improve the accuracy and I am looking forward to better wind info. But I am going in with my eyes wide open. There is no magic.

Fred, I'm really glad you've decided to weigh in. I think you sail like I do and understand better than almost anyone what I'm after here.


So what would be your advice? If not the B&G system, then what? Is there some other alternative besides the CV7?


I am seriously thinking about the CV7. I have had good experience with mine other than upwash issues and have heard lots of good things from quite keen sailors.



Upside of that is it's much cheaper and simpler. Downside is the H5000 can't calibrate it.


There is an interesting prototype system made in Finland which maybe can calibrate the CV7 -- SeaMODE Speed Lab Products


The inventor is a member on here and has participated in many of these threads.

[wingssail]

Originally Posted by Dockhead

Fred, I'm really glad you've decided to weigh in. I think you sail like I do and understand better than almost anyone what I'm after here.

So what would be your advice? If not the B&G system, then what? Is there some other alternative besides the CV7?

I am seriously thinking about the CV7. I have had good experience with mine other than upwash issues and have heard lots of good things from quite keen sailors.

Upside of that is it's much cheaper and simpler. Downside is the H5000 can't calibrate it.

There is an interesting prototype system made in Finland which maybe can calibrate the CV7 -- SeaMODE Speed Lab Products

The inventor is a member on here and has participated in many of these threads.

I'm sorry I can't give much advice about other systems. I've sailed on boats with various systems, some worked, some didn't. But most of my experience has been on B&G boats. That seems to be the standard.

One thing that puzzles me is your comment about incompatibility of CV7 with B&G. Does this mean you plan on having a B&G H5000 system for computation and display? Do you know for sure that you can't calibrate the CV7 from the B&G H5000? If that is the case then, if it was me, I'd go with the B&G sensors. You're going to be into the system for quite a lot of money in my books so an all B&G system is going to give you confidence that it all is going to work together and work well. However $4000+ for a vertical MHU is pricy, and that is just one component. I have a new type 213 unit with vertical spar I plan to install this year, so that is my vote. B&G has a new MHU series for about the same money, WS700. It is apparently NMEA compatible?

Only you can decide whether it's worth the money but I wonder if the added precision will be noticeable.