Autohelm ST50 Wind calibration

FulmarJeddo

FulmarJeddo

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I have a ST50 Wind instrument that after repairing a damaged cable where it exits the mast has worked fine. The last couple of times out this year I found the wind vane had gone out of callibration and was reading about 10 degrees out. This can be adjusted and works fine for the rest of the trip, but is out again after being switched off for a week or two. The mast head unit is secure and doesn't seem to be the cause. Is there an internal battery that retains the calibration and is it replaceable?
 
Are you sure that you save the settings after calibration. I know with the ST60 the settings are not retained unless saved before switching off.
 
theoldsalt said:
Are you sure that you save the settings after calibration. I know with the ST60 the settings are not retained unless saved before switching off.
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That's a good point. I can't remember reading anything in the instruction book about saving the settings, I will have to check when I'm next at the boat, unless I can find the handbook on line. Thanks.

Edit: I have just been to the Raymarine site and found the manual and I think I must have saved the settings as you have to hold the CAL button to both enter and leave the windvane calibration mode which stores the change.
 
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theoldsalt said:
Available here... http://www.raymarine.co.uk/view/?id=1964&collectionid=13&col=3458
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Thanks, I had found it and edited my previous post before I saw this. I'm pretty sure I came out of the callibration mode correctly and stored the changes. I suspect the age of the unit is starting to show, I have already changed the depth and log for ST60 units as the lighting LEDs had gone weak and were unreadable at night. Unfortunately the masthead unit is not compatible with a ST60 or later display, so I think I may have to start saving for a complete replacement.
 
FulmarJeddo said:
Unfortunately the masthead unit is not compatible with a ST60 or later display...
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Why do you say that? I'm 100% sure they are the same.

More info:

Plevier said:
From Raymarine website - "The ST60 masthead unit is the same as the ST50 one."

Bearings thread http://www.ybw.com/forums/showthread.php?t=282431, from RS, bearingboys, simplybearings ....
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Found the source: "The ST60 masthead unit is the same as the ST50 one..."
http://www.raymarine.com/knowledgebase/index.cfm?view=4315
 
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I recently spoke to raymarine about this. The ST 60 masthead unit will overstate the wind speed by about 15-20% as it can't be calibrated correctly to the ST 50 instrument.They were trying to get me to replace my St 50 with an ST 60 unit as they no longer have the parts for the ST 50 ( I needed a new 5 pin plug- subsequently bought on ebay). Also I have exactly the same problem as the OP with the wind direction on my St50 needing to be re calibrated each time it is switched on which is a bit of a pain but I can put up with it given the price of a replacement unit!
 
Rigger said:
I recently spoke to raymarine about this. The ST 60 masthead unit will overstate the wind speed by about 15-20% as it can't be calibrated correctly to the ST 50 instrument...
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The early ST60 MHU is exactly the same as on the ST50. It may be the later egg-shaped ones that cause the issue.

For the direction vane, I wonder if adjustment on the vane itself would cure the problem.
 
nigelmercier said:
The early ST60 MHU is exactly the same as on the ST50. It may be the later egg-shaped ones that cause the issue.

For the direction vane, I wonder if adjustment on the vane itself would cure the problem.
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Having previously replaced the vane I think adjusting the position on the spindle would be nigh on impossible.

From what has been said it looks as though replacing the display with an ST60 may be an option if one comes up on ebay for a sensible price. Having seen the price that even ST50 displays are going for on ebay I decided to remove my instrument panel for the winter for security so I have it at home. I will try taking the display apart and see if there is any sign of a backup battery.

On a slight drift, I was told by Raymarine that the transducers for the echo sounder and log were compatible between the ST50 & ST60. The echo sounder was when I replaced it last year, however I couldn't get a ST60 log display at what I considered a sensible price on ebay so have now bought a new one from Cactus at only a little more than they were going for on ebay. They were also doing it with a transducer for just a little more than without, so I bought it with the transducer as a "spare." When I connected the ST60 to the old transducer it didn't register the paddle wheel spinning. The wire colours were the same, with the exception of one has a black wire and the other a brown. Rather than mess around trying to work out what the difference was I have started fitting the new transducer which is becoming a bit of a nightmare to route the cable from the fore cabin to the panel above the main hatch.
 
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nigelmercier said:
The early ST60 MHU is exactly the same as on the ST50. It may be the later egg-shaped ones that cause the issue.
.
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That is the case as I understand it. The newer MHUs with the round cups spin faster than the ST50 type. The difference is about 30%. This cannot be calibrated out on the ST50 display. The instruction manual for the ST60 specifies a calibration factor of 0.7
 
earlybird said:
That is the case as I understand it. The newer MHUs with the round cups spin faster than the ST50 type. The difference is about 30%. This cannot be calibrated out on the ST50 display. The instruction manual for the ST60 specifies a calibration factor of 0.7
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It wouldn't be impossible to make a box to change the frequency of the signal, assuming that it is frequency that is measured, and not voltage as often quoted on the RM forums.
 
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