Raymarine st60 masthead wind speed & direction instrument

[victor crowhurst]

On my nc37 this instrument stopped turning after 12 years. It took 12 months to get it down to ground but thats another interesting after dinner talk. The lower microbearing in the lower part. the windspeed part, had rusted and siezed the other three seem ok but I’m going to replace them anyway. I have ordered 4 new bearings from SMB bearings at £1.90p ex Vat each. As the cost of replacement is near £500 for a replacement unit, if you can find one, I think mine is a reasonable cost saving. I’ll take some photos of the assembly and will make them available on request if anyone is in need of diong this job.

[39Schuss]

Thank you for the insight! Please share the photos of the project!

[39Schuss]

Thank you for sharing.

All the parts to repair the units are available from Raymarine although obviously at higher costs. There are a number of kits involved.
On eBay one seller has them. As an example the bearing kit for post 2015 units https://www.ebay.co.uk/itm/Raymarine-Late-ST60-ST60-Wind-Vane-Bearings-O-Rings-windvane/372239943684?epid=1562074264&hash=item56ab3ac804:g:6kYAAOxy0zhTLWhc
This is for a send away repair service.

For the pre-2014 inits the kit is £40 and it is implied you can DIY.

[Trevor Rose]

On eBay a new ST60 masthead transducer £285 is advertised at Ipswich.I replaced a ST50 for about this price but not from this supplier.I was informed that replacing bearings could be tricky maybe an older design
Trevor Rose Nt37

[39Schuss]

Here’s a query regarding the speed they rotate at and their calibration.

At the end of last season I found my indicator was over-reading rather considerably by anything up to 30% (on a club rally after a long beat in a strongish wind I told my fellow skippers I had seen over 40 knots at one stage. I was then laughed at with others saying they hadn’t even seen 30 knots).

On the display head you can set a factor in theory to calibrate the unit. However without a reference that is very difficult. Raymarine on their support pages don’t seem to have any advice, other ‘adjust accordingly’.

Sitting in my boat looking at half a dozen other ST60 indicators going round I was amazed to see the huge difference in speeds. Presumably that is likely to be down to the bearings?

My indicator is only a year old and seems to rotate very well and the factor is set at zero.
One has to assume that an indicator in perfect, as new, condition just needs the zero setting.

So what could make my unit over read so much?

Any views?

[39Schuss]

Just a correction to the previous posting.
The default factor for the wind speed is 0.7 not zero.

[39Schuss]

I found some Raymarine information on the YBW forum about different factors for different combinations of the displays and the ‘mast head units’, which changed around the 2012 period.
The attached image gives the text and details.

Attachments:

1. 

   Raymarine20Wind20MHU20calibration.jpg
   

[39Schuss]

Beware that measuring the speed of wind is a tricky issue in itslef.
Meteoroloist will measure it at a heigh of 10 méters and will average it over one or ten minute, averaging period being much less for gusts of course.

The wind speed varies much with height and with air mass stability and converting a measure made à 18m in an air mass after a warm or a cold front call for abacus. I had some, stored in a place I don’t remember ;-), anyway the text is in French 😉

One last point is that air mass, even on a very small scale like boat distances in a marina, are very heterogenous with lot of eddies. It is not abnormal to see two transducer of the same type revolving at different speed, the faster not being always the same. Thus the need for averaging your mesurement.

[Author]

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