ST60 Wind instrument calibration question

[Wayne]

My wind speed gage is not accurate.  If I remember my instruction manual there is a method of calibrating or adjusting the readout.  Is there any way of getting an objective measurement of the real wind speed?  It seems to me that to adjust to an accurate reading one needs to know what reality is at the moment that one is calibrating.
Any advice appreciated!

[Ken Juul]

Not sure of how to do it, but as far as determining the wind speed I would ask dockmates on either side of you what theirs reads and take the average.

[Roc]

Wayne, is it not accurate when you are docked/anchored (not moving) or while underway?

[Wayne]

I notice the inacurracy when under way--it is usually pretty calm at the dock.

[tommyt]

I almost fell into a trap of adjusting my ST60 today. A friend was at the helm and wanted to know why the ST60 did not agree with the windvane I still like to look at or his perception of where the wind was from. We were sailing in about 20kts. and he had changed to true. I was digging around for my manual when the light went off and I changed back to apparrent. Problem solved.

Probably not your problem, but easy to fall into if others play with the settings on you.
Back at the dock I did see that there are two ways to recalibrate, but happy that I do not have  to do it.

Good Luck,

Tom

[Momentum M]

I went through the calibration of my ST-60 last w-e.  My unit when kind of crazy last fall before putting her on hard for the winter.
I spoke to the dealer over the winter and he explained that sometime "huge" magnetic field would "deregulate" the calibration.  Little did he know that last summer...just before the acting up of my windvane unit that I had gone to Toronto (Can) and that I was in the vicinity of the CN tower.  For the one that do not know about the Tower...let just say that along the side it has a substantial amount of antennas, dish's and the like...creating a big amount of static and magnetic field. 
So, to come back to my dealer, he mentioned that he experienced many complaints about the units not given the proper reading...specially in the Toronto area.  He added that in one case...he fixed the unit and the following week the same problem occurred again.  He also mentioned another area in NY that will also cause the same problem.  I tend to believe him since he did not know about my trip to Toronto.  So, if u guys do encounter this problem...maybe u should look around to see if u do (or don't) have a similar "magnetic field".

If you don't have the instructions...let me know and after next w-e, I will bring them back and will detail the procedure for calibration.



As I said, last Sunday, as I was cumming back to my marina I decided to calibrate my unit.  I got the book out and started.   I was very surprised to see how easy it was.  Just follow the instructions in the quick reference card that came with the boat.
It was a very calm day so I did my 3 circles (slow circle at less than 2 kn and ea circle should take approx 3 min).  The unit told me that it was callibrated and then followes the adjustment for the compas.  It gives u the chance to adjust both the reading on the ST with the compass so they both have the same reading.
Know everthing is newly calibrated and unless I go back in front of this tower...I should be OK.  (Unless I do go by another of these magnetic field!!)

[Wayne]

Too add a little more information . . .
My factory base unit (the readout mounted at the help) was defective, and was 'swapped out' a couple of weeks ago.  My wind direction is fine now (that is what had failed), but the wind speed has never seemed correct based on observation.  The original unit, in my purely subjective opinion, was reading about 20% too high a wind speed (yes, I know it is more windy 50' up than down at sea level).  Last weekend with the replacement unit I think it was reading about 20% too low a wind speed (again, based on subjective observation).  Part of my opinion of it reading low is that by the instrument's reading I was in average 18-19 knots of wind.  Water surface conditions (my subjective reading) said well over 20 knots.  Also, I had the furling main reefed to almost a #2 reef, was pinching, heeling like crazy, and making boat speed in the high 6's surging frequently over 7.  This performance doesn't make sense at wind less than 20 knots.
So, what I really need is a way to objectively measure wind speed at about 50' up.  Otherwise, I think I will just adjust the thing to my best subjective guess.
Thanks everyone for all the replies!

[tonywright]

Wayne

Were you reading apparent or true?

If it was "true" then do you have a GPS and a compass connected via Seatalk? If not, then it will probably be using data from your knotmeter, plus the calculated apparent wind angle to calculate true from apparent. If your knotmeter is reading high (due to current, or whatever) then your "true" readout could seem low. Also if your wind angle is not properly calibrated. (You can tell if the GPS is properly connected by checking to see if you have an SOG reading on the speed instrument.)

Tony

[Wayne]

I do have a Raymarine GPS; don't know if Seatalk is active or not.  When my wind instrument was reading low, I was sailing 'upriver' against a pretty strong current.  My knotmeter has historically seemed pretty close to right on; speed readings seemed to 'fit' with watching how fast foam was shooting by.  I assumed that the wind speed reading came straight from the anemometer (apparent wind)--I never thought of it being involved with the GPS or knotmeter (on apparent; I know that on true it needs input of boat speed and direction relative to wind).