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-   -   ST60 Wind Transducer does not show correct true wind (https://www.sailnet.com/forums/general-discussion-sailing-related/264690-st60-wind-transducer-does-not-show-correct-true-wind.html)

TakeFive 09-13-2016 01:52 PM

ST60 Wind Transducer does not show correct true wind
 
I've registered for the Raymarine support forum, but their site admins are taking their dear old time approving my membership. In the meantime, I am hoping that one of you might have a hint or two to help me address my problem:

My configuration:

I have ST60 Wind, Speed, and Depth transducers, ST4000+ wheel pilot, and a Garmin 2010 chartplotter. These instruments came with my new (to me) boat. I did not install them.

My speed transducer's paddlewheel is sitting in the bilge. I have the blank in the through-hull, and have the speed control head set to display SOG.

My background:
I have had Raymarine ST60 instruments on a past boat, and have quite a bit of interfacing experience with SeaTalk and NMEA 0183 protocols.

What works:
My wind transducer shows apparent wind fine. It may need a little tweaking of the calibration, but it's not terrible, and I have more important things to fix first.

What's broken:
The wind transducer is not showing the correct true wind. It shows exactly the same speed for true wind that it does for apparent wind, regardless of speed or direction of the boat. True direction is also almost the same too (within a few degrees). I can be motoring 5 kts straight into a 5 kt wind, and both true and apparent wind will show up as 10 kts. I can be sailing on a broad reach, and true/apparent wind speed are the same, and direction almost exactly the same. The direction agrees with visual observation of my masthead Windex.

The first hypothesis might be that the instrument is not getting any speed data, or is getting a value of zero (since true=apparent when speed=0). But the speed control head shows SOG just fine. Although I have not opened up the NavPod to view the wiring, I assume that the chartplotter's output wires are connected to the NMEA input terminal on the Autopilot, and the Autopilot is passing that data through to the SeaTalk netowork. That's the only way I can see that the speed control head would be able to display SOG.

So this leaves the question: Why isn't the wind transducer making the appropriate vector calculations to display the correct true speed and direction?

I've looked through the manual and cannot find any settings to change speed input (for instance, from SOW to SOG). So I'm stumped.

SVAuspicious 09-13-2016 03:00 PM

Re: ST60 Wind Transducer does not show correct true wind
 
I love the easy ones.

Raymarine only uses STW (from the paddlewheel) to calculate true wind. With the paddlewheel in the bilge the algorithm gets 0 so true = apparent. Clean your paddlewheel and stick it in the hole.

oldlaxer1 09-13-2016 04:25 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Quote:

Originally Posted by SVAuspicious (Post 3658506)
I love the easy ones.

Raymarine only uses STW (from the paddlewheel) to calculate true wind. With the paddlewheel in the bilge the algorithm gets 0 so true = apparent. Clean your paddlewheel and stick it in the hole.

So if the paddlewheel is gummed up and reading low, True will indicate less on a downwind leg?

TakeFive 09-13-2016 04:31 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Quote:

Originally Posted by SVAuspicious (Post 3658506)
I love the easy ones.

Raymarine only uses STW (from the paddlewheel) to calculate true wind. With the paddlewheel in the bilge the algorithm gets 0 so true = apparent. Clean your paddlewheel and stick it in the hole.

That's what I suspected. First thing I looked for was a menu in Dealer Setup that would allow selecting SOG for this, but didn't find it in the manual. As I'm sure you know, SOG is a much more reliable and accurate basis than SOW for the required vector calculations. I guess the only logical explanation for doing it that way is that GPS speed was much less common back when the ST60 series was developed.

Unfortunately my paddlewheel is in a very inconvenient location. The air conditioner tray was installed right over top the through hull, which makes it all but impossible to reach. If I could contort my arm and wrist to get to it, I am really concerned that I might get the blank plug out, and not be able to get the angle right to get the paddlewheel (or the blank) back in. Meanwhile, the water continues to pour into the bilge.

Also, my paddlewheel is not free-wheeling. It has severe resistance, so it needs servicing. I can't figure out a way to disconnect the cable to get it to a work bench where I might be able to do some decent cleaning on it. (Any hints on how to do this?)

It is good to have an explanation for this, so I can stop wondering what's wrong. (Thanks!) I will just use apparent wind for now.

I have a few options to circumvent this problem. I have a Raymarine-NMEA converter from my old boat that could take the apparent wind from SeaTalk and feed it by Wifi to my tablet software that can convert to true wind using SOG from the GPS. I doubt that the converter will fit into my NavPod, so running the wires to a remote location will be a tedious job. That will go on my ever-growing list of winter projects. Maybe someday I will get to it.

BarryL 09-13-2016 06:31 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Hey,

Some info for you:
If the paddlewheel isn't turning freely you have two choices; Remove the paddle wheel (use a paper clip or something like that drive the wheel out. Then use emery paper to clean the pin. Or, buy a new paddle wheel. The kit comes with wheel, pin, and gaskets. Unfortunately, that won't help you to install the paddlewheel. If you do decide to install the wheel, make sure you paint it with antifouling paint. There is special paint for transducers, but they don't seem to work well. You can dive the boat to clean the wheel too.

Your garmin plotter SHOULD be able to display true and apparent wind. My 740S does and it uses SOG instead of STW. I have an 'environment' page with wind information. This assumes that your plotter is getting wind data! If not, you can convert the old seatalk to NMEA 2000 and then you are set!

Good luck,
Barry

Maine Sail 09-13-2016 06:52 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Quote:

Originally Posted by TakeFive (Post 3658442)
ST60 Wind Transducer does not show correct true wind


Snip....

My speed transducer's paddlewheel is sitting in the bilge.


Can do true without the speed log....

TakeFive 09-13-2016 08:16 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Quote:

Originally Posted by Maine Sail (Post 3659010)
Can do true without the speed log....

Haven't the newer ones been updated to accept SOG from a GPS?

senormechanico 09-17-2016 08:05 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Move the air conditioner??

albrazzi 09-17-2016 10:14 PM

Re: ST60 Wind Transducer does not show correct true wind
 
If you put it in make it easy to get to, you WILL need to clean regularly.

capta 09-17-2016 10:35 PM

Re: ST60 Wind Transducer does not show correct true wind
 
Quote:

Originally Posted by Maine Sail (Post 3659010)
Can do true without the speed log....

All righty then. I have a ST-60 speed log that always reads slow by several knots, so please explain.
Is my Garmin 3010 too old to connect to the ST-60 system????


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