Calibration of wind speed.

Sneaky Pete

Sneaky Pete

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I have calibrated the wind direction on my Raymarine ST60 wind speed instrument. Is it possible to calibrate the wind speed if so how is this done? I have read through the instructions that accompany the instrument from Raymarine but do not see anything about calibration of wind speed.
 
macd said:
What would you propose to calibrate it against (incidentally noting that whatever it is will also need to be at the top of the mast)?
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Yes, quite. I hadn't thought of that - Well done. So rather impractical.

It would be interesting to know how accurate Raymarine attempt to make them/ claim them to be, and whether they are tested in the factory. However with a constantly rolling and pitching vessel (greatly exaggerated at the masthead) we should not expect too much.
 
Sneaky Pete said:
I have calibrated the wind direction on my Raymarine ST60 wind speed instrument. Is it possible to calibrate the wind speed if so how is this done? I have read through the instructions that accompany the instrument from Raymarine but do not see anything about calibration of wind speed.
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Calibrate against GPS SOG. If you do it on a windy day then do a run into the wind followed by another with the wind with the advantage that you can get to higher apparent wind speeds. You can calibrate the log the same way going into and then with a tide.
 
Even if you managed to fully calibrate the wind speed instrument what would you do with the information. I for one don't use this info to indicate when to reef for example.
I check wind speed at times purely out of curiosity.
 
theoldsalt said:
Even if you managed to fully calibrate the wind speed instrument what would you do with the information. I for one don't use this info to indicate when to reef for example.
I check wind speed at times purely out of curiosity.
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Wind speed is a useful tool to have, what you seem to be saying is forget a wind speed instrument guess it instead, brilliant. I use wind speed for that reason to let me know when to start thinking of reefing, especially before leaving a berth.
 
you also need to take into account any 'averaging. IIRC the ST60 stuff averages the windspeed to even out momentary gusts, the averaging period used to be adjustable on ST50 instruments so probably is on ST60s as well. our current garmin stuff is calibratable but I haven't changed the factory setting, so it probably reads in Taiwanese!
 
Sneaky Pete said:
Wind speed is a useful tool to have, what you seem to be saying is forget a wind speed instrument guess it instead, brilliant. I use wind speed for that reason to let me know when to start thinking of reefing, especially before leaving a berth.
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To me the effect of wind on the boat is more important than an accurate value on an instrument. I have often found that wind speed and direction on my berth bears no relation to what is happening in open water. It could be much higher or lower and in a completely different direction. Sometimes "windguru" is more realistic than my own wind indicator.
 
As I get older and more cautious, I find the longer you stay in harbour/ on mooring debating matters the less likely you are to go sailing. So my advice if you are considering reeling put in the reef and get out of there. I have recently installed a meteoman wind instrument which tells me a the wind speed and b that it is varying quite a bit as I ponder my options. I usually end up switching it off and just going for it.
 
theoldsalt said:
Yes, quite. I hadn't thought of that - Well done. So rather impractical.

It would be interesting to know how accurate Raymarine attempt to make them. However with a constantly rolling and pitching vessel (greatly exaggerated at the masthead) we should not expect too much.
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Any company producing such a product will calibrate very accurately and the good news is they will all be the done similarly. As for pitching and rolling forget it instruments compensate for small fluctuations in readings.

theoldsalt said:
To me the effect of wind on the boat is more important than an accurate value on an instrument.
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Well said. That is why for a given wind speed you will know what the effect on the boat is. It will always be like that. That is why accurate instrumentation is so important. I take it from your comments you would not use a speedo in a car, just stick your neck out of the window to gauge the apparent wind speed.
I take it from the various comments it appears either to be too late in the evening for sensible answers or there is no way of calibrating a wind speed instrument.
 
I think most people would use wind speed on a sail boat as a relative thing. ie not so concerned that actual knots are precise. Rather you knopw that last time it hit 30 knots you were glad to have a reef in and so now the dial shows 28 it is time to reef again. Or that 20 knots witha reef in might from previous experience looking at this anenometer that you would be OK without reef. etc So to the OP don't worry about calibrating your wind speed just start logging what it says compared to actual conditions. good luck olewill
 
reeac said:
Calibrate against GPS SOG. If you do it on a windy day then do a run into the wind followed by another with the wind with the advantage that you can get to higher apparent wind speeds. You can calibrate the log the same way going into and then with a tide.
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Really don't think this would work - far too much short-term variation in windspeed, unlike tides where I do a two-way run to calibrate my log over about 2 minutes each way.

Anyway - why bother - I regard the windspeed dial to be pretty irrelevant really, as is the wind direction one. The boat happened to have it fitted when I bought it but I'm not sure I'd bother fitting one if I was kitting out a new boat. What matters is what the wind does to the seas and the sails.
 
jwilson said:
Really don't think this would work - far too much short-term variation in windspeed, unlike tides where I do a two-way run to calibrate my log over about 2 minutes each way.

Anyway - why bother - I regard the windspeed dial to be pretty irrelevant really, as is the wind direction one. The boat happened to have it fitted when I bought it but I'm not sure I'd bother fitting one if I was kitting out a new boat. What matters is what the wind does to the seas and the sails.
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Depends on how much experience you have in reading instruments. That's how SWMBO and I calibrated our wind instrument but we're both [retired] scientists and have no problem doing mental averaging of readings whilst comparing with SOG readings. Better than taking a weather forecast value as a standard.
 
Sneaky Pete said:
I use wind speed for that reason to let me know when to start thinking of reefing, especially before leaving a berth.
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I think that's what most people use wind speed for. So the actual wind speed doesn't matter - it's knowing how your boat behaves when the number on the dial reaches a certain figure.

If you know that you need to take the first reef when the ST shows 18 knots, it doesn't matter much if it's really blowing 15 or 20

Wind speed is useful for bragging, though.
 
Most useful cal may be to motor into wind at 5knots and check the indication goes up by 5, then motor downwind and check it reduces true wind by 5.
As others have said, the sails tell you how windy it is, but I find a windspeed reading valuable when sailing downwind, to tell me what I'm going to see when I head up onto a beat.
Apparent wind can be very deceptive on deck when running.

Wind speed can vary with height by different amounts on different days, so cal'ing to another anemometer can send you around in circles.
 
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