ST50 Wind masthead unit question

Robin

Robin

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Anyone know the makeup of the ST50 Windspeed/direction masthead unit please? Ours stopped spinning and a friend who went up the mast for me last night found what looked like a 'O' ring from the main part between the direction vane and the windspeed cups had fallen out of a groove and dropped down, jamming the cups. He replaced the 'O' ring and taped it over to keep it in place temprarily, but what IS this? Is it a seal between two parts of the casing or what and what is inside the case, anything that really needs to stay dry or is this a non-powered piece of electronics?
 
Both the wind vane on the upper side and the spinning cups on the lower side are mounted on shafts through plastic holders that are push fitted into the hollow aluminium vertical tube. Each of the plastic units contains the sensing electronics and are held in place by two "O" rings. These "O" rings both hold them in place and provide waterproofing. Inside the plastic unit and on the shaft of the wind vane is a magnet, the position of which is sensed by the electronics inside. On the shaft of the spinning cups are four small magnets which rotate over a sensor and give a pulse from which the speed can be calculated. So the answer to your question is "yes" there are electronics inside and they do need to be kept dry.

If I were you I would remove the masthead unit---quite simple as it's only a twist to lock plug on the end of the shaft that goes into the masthead mount. Once you have brought it down from the mast remove the cups from the lower shaft---again easy as all you need is a small allen key to release the grubscrew that holds the cups onto the shaft. You will then be able to prise out the plastic part that contains the electronics (don't pull it out too far as it remains connected by wires to the actual masthead unit. You will then clearly see the two grooves in the plastic where the "O" rings fit. Two new "O" rings, some silicone grease, reassembly and it should be fine.
 
Many thanks for that very useful information. I haven't seen it as someone else did the mast climb for me and couldn't see why the O ring had come loose, maybe UV perhaps as it was definitely stretched he said.

Anyway I'm looking for a spare masthead unit on the wanted forum so we can then do a recon and swap operation and have a ready spare if ever needed because I think these are no longer available.
 
You will be very lucky to find a decent second-hand one as they are as rare as an honest politician. I've seen second hand units go for well over a £100.00 on Ebay and you still have no idea what condition they are in or even if they are working. You can buy a complete digital replacement unit on Ebay--search for ST50 wind----but make sure that you are sitting down before you do it, they cost an unbelievable £404.95 delivered
 
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Does the ST60 unit work with ST50 or is this the £400 plus one?


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The ST60 transducer will connect with the ST50 display, but the speed reading wil be wrong. This answer can be found if you search Raymarine Q&A under ST50 instruments using the search term:- transducer compatibility. It is Q. no.45
Sorry, can't seem to paste the link.
The ST60 display has a speed calibration function. Mine is set to 0.7 to work with an ST50 transducer.
 
Panic over!

Thanks guys, Richards links got me really worried so I contacted my local friendly expert at Greenham Marine in Poole and I have no need to worry. Apparently the version of masthhead transducer we have has an external red O ring that was a cosmetic addition not fitted on later ones and the birds like to pick at them, hence our problem. The good news is that all that is needed is to dump the old O ring which has been stretched by the little busteds, the waterproofing rings are inside the body and not affected.

I also discovered that the ST60 transducers WILL fit the ST50 instrument system and work BUT the windspeed reading will be wrong by about 20% high - not what you want if you a nervy crew!
 
Can I hijack the question to ask how to test if the wind direction vane is working?
the wind speed is easy as the pulses can be read on a meter but how does one check the direction indicator? I ask on behalf of a friend who has a problem with the wind direction readout fluctuating all the time. From memory I think there are 12 cables at the masthead and don't know which are associated with the direction readout. and how to test!!
 
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Can I hijack the question to ask how to test if the wind direction vane is working?
the wind speed is easy as the pulses can be read on a meter but how does one check the direction indicator? I ask on behalf of a friend who has a problem with the wind direction readout fluctuating all the time. From memory I think there are 12 cables at the masthead and don't know which are associated with the direction readout. and how to test!!

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According to Raymarine, the blue and green wires carry port and stbd wind direction signals respectively, each varying between 2 - 6 volts wrt the screen.
If yours is a Raymarine transducer, there's a total of 5 wires including the screen.
Red is power; 8v. Yellow is windspeed; 0 - 5v. approx. AFAIK, it shouldn't pulse.
 
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