ST60 Wind Instrument Information

[nigelmercier]

I had previously asked Raymarine about Relating Vane RPM to Speed on an ST60 Wind Instrument, they told me this was "proprietary information. I have now done some tests. First of all, I need to clarify something about the signals the ST60 Wind produces. The standard Raymarine ST60 Wind test procedure says:

Red to shield should read 8 volts DC steady. This is the masthead power supply, coming from the ST50/ST60 display head. If the head is damaged, you may need to provide this power from another source to test the masthead.

Blue to Shield should read anywhere between 2 and 6 volts DC. This is the port side directional element. The voltage changes as the vane turns.

Green to Shield should read anywhere between 2 and 6 volts DC. This is the starboard side directional element.

Yellow to shield should read between 0 and 5 volts DC. This is the wind speed circuit. The faster the wind is blowing, the higher the voltage will read.

Calling the Blue and Green signals "port" and "starboard" is misleading. They are the sine and cosine waves produced by the transducer. In other words, if you spin the wind direction vane you get two sine-wave signals, 90° apart.

The Yellow wind speed circuit does not produce a varying voltage, it produces a square wave, at a frequency of twice the shaft rotation speed. Some voltmeters may register this as a changing voltage, but again this is misleading. Rotating the shaft at 600RPM (10 per second) produces a 7V square wave at 20Hz, and on an ST60 Wind with factory defaults this displays a wind speed of 20kn.

I hope this information is useful to someone.

LATER Follow-up thread regarding calibration http://www.ybw.com/forums/showthread.php?424404

 

[aluijten]

Excellent!. That will make it easier to do fault finding when the time it there.

I'm guessing the ST50 transducer (with the square cups) will work similar but at lower RPM for identical wind speed.

Arno

 

[Mistroma]

Many thanks Nigel. I spent a fair bit of time tracking down a fault a couple of years ago. I followed the Raymarine test procedure you mentioned and it seemed to indicate that the masthead unit was working. The problem persisted and seemed to be cured a couple of times after cleaning various connections, but returned soon afterwards.

The problem was finally traced to slight corrosion inside the connector at the top of the mast. Easily solved with some connector cleaner and Contralube. I was able to push the nozzle over every pin in turn and squeeze a tiny amount of Contralube on each one.

The information you provided would probably have allowed me to trace the fault more quickly. The standard test procedure simply indicated that the masthead unit was doing something and not completely dead.

 

[FWB]

Thanks for posting Nigel.
Just in case an electronic fault is found then the Transducer circuit board can be easily replaced, though it's hard to see why it would fail...
http://hudsonmarine.co.uk/index.php?module_display=41&pid=142934

Note the exploded diag does not display in Safari on my iPad but it shows in icabmobile.

 

[nigelmercier]

... Relating Vane RPM to Speed on an ST60 Wind Instrument...
Rotating the shaft at 600RPM (10 per second) produces a 7V square wave at 20Hz, and on an ST60 Wind with factory defaults this displays a wind speed of 20kn...

Further to this, I have now done some tests using the actual wind vane, the newer "egg shaped" type as supplied with the ST60+ I believe. Today was very calm (less than 2 knots of wind), and blowing across the road where I tested (I did a few runs in each direction just in case). This was the setup I used, I shot a video of this as I drove:

On the left is meter showing frequency (20.42 Hz), a GPS showing 37km/hr (19.98 knots) and the ST60 Wind Instrument (20.1 knots).

As you can see, the factory defaults for this new vane type produce more or less the correct reading on an ST60 Wind Instrument. I'm a bit surprised about this, as I understood that the newer vanes had to be de-rated by a factor of 0.7 (I think).

For your amusement, here is a shot of me returning home; this is part of an image from a video captured on one of my security cameras:

 

[johnalison]

That's very impressive. I hope you are still in good form when they let you out.

 

[FWB]

The ST60 and i60 instruments come already set to 0.7, have you changed this?
I would have thought that Raymarine would have done their own calibration hence the default of 0.7 set by them.

 

[nigelmercier]

The ST60 and i60 instruments come already set to 0.7, have you changed this?
I would have thought that Raymarine would have done their own calibration hence the default of 0.7 set by them.

Ah, good point. When I set the default I assumed it would be unity.

[Later] I checked on my reset unit, you are correct; the factory default is 0.7