Raymarine ST40 wind instrument

Praxinoscope

Praxinoscope

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No matter how much I try to adjust the ST40 wind indicator on my boat, it will not give an anywhere near accurate wind direction, the speed indication is accurate, the direction reading can be anywhere from 30 degrees to 200 degrees out.
To be honest I really don’t see how a single unit at the masthead can give a sensible Reading* for both, but I assume that it is meant to work.
Any ideas on why I can’t get this to give at least a fairly close reading to what my Windex is indicating?
 
Assuming that it does have a vane as well as rotating cups, like the ST50 and ST60, then it is almost certainly one of the components in the circuitry in the mast head which has failed. My ST60 failed in a similar vein and I replaced the circuit board recently with one bought on eBay and it now works fine.

Richard
 
RichardS said:
Assuming that it does have a vane as well as rotating cups, like the ST50 and ST60, then it is almost certainly one of the components in the circuitry in the mast head which has failed. My ST60 failed in a similar vein and I replaced the circuit board recently with one bought on eBay and it now works fine.
Click to expand...

The ST40 used a "Rotavecta" transducer, just 3 rotating cups. One of the cups has an "ear" on it, so is affected more by the wind than the other two. This results in a tiny unevenness in the rotational speed, which the electronics use to decide the wind direction.
 
Praxinoscope said:
No matter how much I try to adjust the ST40 wind indicator on my boat, it will not give an anywhere near accurate wind direction, the speed indication is accurate, the direction reading can be anywhere from 30 degrees to 200 degrees out.
To be honest I really don’t see how a single unit at the masthead can give a sensible Reading* for both, but I assume that it is meant to work.
Any ideas on why I can’t get this to give at least a fairly close reading to what my Windex is indicating?
Click to expand...

Have you gone through the User Calibration procedure?
 
pvb said:
The ST40 used a "Rotavecta" transducer, just 3 rotating cups. One of the cups has an "ear" on it, so is affected more by the wind than the other two. This results in a tiny unevenness in the rotational speed, which the electronics use to decide the wind direction.
Click to expand...

Ah, I see. Assuming that the calibration has been re-done, it's probably still an electronics failure in the MHU but I've no idea whether you can replace the board in such elderly equipment?

Richard
 
Thanks for your replies, I have a feeling that the ‘rotavector’ system may be a bit of a clever idea, but I have been thinking of changing this unit, especially as I have gone through the calibration procedure a couple of times with no joy, so it looks lik3 a NASA unit to be installed this winter.
 
I have a similar unit and had a similar problem, given that you seem to be recieving relatively accurate wind speeds and it is only directional issues it suggests the masthead unit is working. I solved my problem by entering the advanced calibration proceedure and using the offset facility. Apologies if you have already tried this, i am only trying to offer a solution before you spend loads of cash. I did this at the quayside and then again at sea with excess of 12kn of wind. i found that with some tweaking of the offset, i could make mine fairly accurate. I also checked windspeed with a neighbour with Raymarine i60 instrumentation and found it to be very accurate given the difference in the height of our masts.
On a different occasion i had an issue with the wind speed being erratic, this problem was a small amount of coorosion on the wires where they were connected at a junction box inside the boat for mast stepping. The riggers had used only a choclate box connection. I cut off the corroded ends used plenty of grease and refitted a decent connection. Hey presto!.works great
 
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Besonders said:
I have a similar unit and had a similar problem, given that you seem to be recieving relatively accurate wind speeds and it is only directional issues it suggests the masthead unit is working. I solved my problem by entering the advanced calibration proceedure and using the offset facility. Apologies if you have already tried this, i am only trying to offer a solution before you spend loads of cash. I did this at the quayside and then again at sea with excess of 12kn of wind. i found that with some tweaking of the offset, i could make mine fairly accurate. I also checked windspeed with a neighbour with Raymarine i60 instrumentation and found it to be very accurate given the difference in the height of our masts.
Click to expand...

Thanks for your suggestion, I have tried the offset, but this didn.t seem to solve the problem , however as There are still 3 months before lift-out I will have another go at it, I will also try to linearise it again.
 
Cannot help - but we have had the same unit for 20 years, without issue - except a cockatoo destroyed the cups and I had need to invest in a new set of cups.

Its a clever idea that is, or was, cheap, cheerful, works and good enough - as we don't race.

Jonathan
 
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