Autohelm ST60 Wind issues

Tim Good

Tim Good

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On a passage the other day... a rather windy passage from Canary Islands to the Azores, my wind reading became a tad unreliable.

I have two ST60 units that show me wind strength and direction. One is an ST60 Wind angle instrument and the other is a ST60 Multi. The wind direction appears to be ok but the speed began being erratic. This was shortly after it was reading 45kts... Anyway it slowly became unreliable, giving me readings of 5kts when it was clearly 15+. It now reads 0 but the wind direction does appear to be ok. Can I assume that the ST the60 units mselves are unlikely to be the issue. I know they are daisy chained and so one can cause issues to others... I did go up the mast and the Raymarine windex / anemometer appear in visual working order. Is there a way to test this perhaps with a multimeter?

Thanks!
 
Mmm, I saw a thread on cruisersforum where a guy did the Raymarine tests, they failed so he took the masthead unit off and had a "fixed price" repair. No fault found, but still charged. It turned out to be a fault with the cable.

I have an interest in this as our masthead unit did much the same - intermittent windspeed then failed. I haven't sorted it yet as I'm reluctant to climb the mast. Also using a 'scope I can see there is a very weak signal on the line and I'm currently thinking of some electronics for a budget solution to the problem.
 
Nevertheless it's worth checking cable continuity to the masthead while you're up there, before filling Raymarine's coffers. Obviously needs someone at the other end to assist
 
Just some more info whilst I’m here on this... during the particularly bad weather when the wind data became dodgy, I was getting an electric shock from my wheel and backstays!

I was in a particularly bad gale and waves we crashing over the cockpit. As I tried to deploy a drogue I was getting a fairly back electric shock when I touched the backstay. Now that obviously leads to the masthead. I was also getting a shock from the steering wheel! Everything was soaked in salt water and I’ve yet to determine where the problem originated from since it dried-off it was fine.

I could test at the time as once the drogue was out I was getting pooped by some fairly big waves into the cockpit so I was hiding down below.

I wonder if some stray live was putting a current through the rigging which then made the masthead instrument faulty.
 
northcave said:
Can you give me an idea of how to do that please?
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Take a short piece of wire with bared ends to the top of the mast. Identify the screen on the masthead cable connector. Then use your piece of wire to connect the screen to each of the other pins sequentially. Meanwhile your assistant at the mast base terminal block or back of the instrument (whichever is more convenient) uses a meter to check continuity between the screen and each pin in turn in time with you up the mast. Walkie talkies or very loud voices needed here. If every pin interconnects your cable's OK. The exact pin-out is unimportant but it will be something like this:-

Please note the connectors on each end of the cable are wired differently, but I'm sure you'll manage

masthead conns.jpg
 
RichardS said:
You can test all the voltages at the bottom the mast and quickly determine whether the wind direction and wind speed circuits are working properly.

Full details are on the Raymarine website or a number of threads on here.

Raymarine Masthead Wind Transducer Test

Richard
Click to expand...
Richard,

So I tested a giant the values that document and mine are:

- Red to shield should read 8V DC steady
Mine = 7.7

- Blue to Shield should read anywhere between 2V and 5.8V DC.
Mine = 7.5v

- Green to Shield should read anywhere between 2V and 5.8V DC.
Mine = 7.5v

- Yellow to shield should read between 0V and 5V DC
Mine = 6.5v

Would this suggest the live is escaping through to all the other wires somewhere?
 
Are those values with the instrument disconnected? If measured when connected to the instrument your wind direction could not be working.
 
northcave said:
These were measured with the instruments connected. Both speed and direction now don’t seem to be working.
Click to expand...
These were my voltages after I replaced the circuit board in my MHU: Raymarine ST60 wind transducer refurb. problem, with photo

As you can see, the two sines waves from blue/shield and green/shield are 90 degrees out of phase so, apart from a crossover voltage around the mid-point of 3V, if one voltage is high then the other is low. Yours are both too high so something is definitely not right and perhaps it could be some kind of shorting.

The only thing I can suggest is that you do what I did and take the MHU down and bench test it. If it tests OK on the bench then the problem is with the cabling rather than the MHU. The advantage with bench testing is that you can test the unit at 90 degree orientations and plot the graph whereas when its mounted it's much harder to plot the different directions.

Richard
 
I wouldn't hold out much hope with a bench test. With your other comments about electrical shocks it sounds like your masthead unit has been fried by lightning or at least very high static voltages. Would your insurance cover a replacement if the damage is accepted as accidental?
 
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Actually I'm grateful for your original post. I have never (yet) encountered the severe met conditions you've described and it's very interesting to hear your report on what happened and how you've dealt with it. Thanks!
 
northcave said:
Just some more info whilst I’m here on this... during the particularly bad weather when the wind data became dodgy, I was getting an electric shock from my wheel and backstays!

I was in a particularly bad gale and waves we crashing over the cockpit. As I tried to deploy a drogue I was getting a fairly back electric shock when I touched the backstay. Now that obviously leads to the masthead. I was also getting a shock from the steering wheel! Everything was soaked in salt water and I’ve yet to determine where the problem originated from since it dried-off it was fine.

I could test at the time as once the drogue was out I was getting pooped by some fairly big waves into the cockpit so I was hiding down below.

I wonder if some stray live was putting a current through the rigging which then made the masthead instrument faulty.
Click to expand...


I think that your report of electric shocks requires thorough investigation before you fit any new expensive gear. I'm not sure that a lightening strike would manifest itself in this way, certainly from what I've read and experienced in the past. But I don't know for sure. I've never had a strike on a boat but had 2 in my house, it came it went, leaving a trail of damaged equipment throughout the house in both cases.
The fact that all the mast and rigging was soaked through and your electrics were on may indicate damaged cabling or shorts to earth in the mast or associated areas when wet.
Once dry it may correct itself. Again I don't think a 12 volt dc supply would give you a bad shock as you put it, but with wet salty hands you could certainly feel it. Put a 9 volt battery on your tongue and see what you feel. :)
Sounds like the damage is done and you may have to replace masthead unit if your checks point that way but you don't want the same thing again next time you're out in bad weather.
 
greeny said:
Sounds like the damage is done and you may have to replace masthead unit if your checks point that way but you don't want the same thing again next time you're out in bad weather.
Click to expand...

Indeed. I’m just in the Azores at the moment and want to set off back to the UK the next 2 weeks. Would have been nice to have a wind instrument for that at least. Anyway it’s certainly no totally necessary as these gadgets are relatively new to the world of off shore sailing so I’m sure I’ll cope without if I can’t fix it.

But I agree I do need to figure out where the problem originated from.
 
GHA said:
Ah, getting mixed up. Still a worry though, some underwater metal fizzing away.....
Did you have an inverter running? Seems unlikely for 12v to be felt physically.
Click to expand...

Well that’s What I thought but not didn’t have the inverter running. It was really bad conditions at the time so had no need to be using the inverter. It was strong enough to be giving me a shock through the wet leather on the wheel. Also the backstays. I’ve checked the masthead and nothing untoward. No damaged connections or loose wires to lights etc.
 
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