anemometer?

[DaveC426913]

I really want to know the wind speed better. I've got a little handheld one, but I doubt it's very accurate. It's one of these little things:



I guess I could get a better quality one, but I think it will still be biased by being only 10 feet above the water on a boat.

Is there one I can put on my masthead that isn't outrageously priced? Or can I just get a handheld and spend more money on it?

[JohnCFI]

I don't know about not being outrageously priced, seems all the manufacturers think because we have boats we must be rich!!!

I have this one, it works fine....

http://www.nasamarine.com/proddetail.ph ... ipper_Wind

[dlandersson]

Here's mine, seems to work ok - not especially elegant.

http://www.amazon.com/gp/product/B005DF ... UTF8&psc=1

I really want to know the wind speed better. I've got a little handheld one, but I doubt it's very accurate. It's one of these little things:



I guess I could get a better quality one, but I think it will still be biased by being only 10 feet above the water on a boat.

Is there one I can put on my masthead that isn't outrageously priced? Or can I just get a handheld and spend more money on it?

[Russ]

I think it depends on what it's worth to be more accurate with wind speed.
Frankly, that handheld for the price would satisfy my wind speed curiosity. In fact, I have one similar.

--Russ

[Crikey]

I've used the little whirling cups type. Lots of fun when you get smacked in the face trying to read the dial.

R.

[DaveC426913]

I think it depends on what it's worth to be more accurate with wind speed.
Frankly, that handheld for the price would satisfy my wind speed curiosity. In fact, I have one similar.

--Russ

I think the issue is that I don't trust it.
It is very finicky at being aligned right. You turn it back and forth in the wind until you find the angle where it reads the highest. But that's pretty impossible to do if the wind itself is changing. I tend to spend 2-3 minutes turning it back and forth and just guessing what I think is the highest reading.

Plus, it doesn't even measure in knots! It measures mph, metres/second and Beaufort, but not knots! (I mean, it's trivial to convert mph to knots, but still...)

[DaveC426913]

Does anyone have any opinion about accuracy of wind readings in the cockpit versus at the masthead?

[Russ]

I would expect the mast to be more accurate as it has few objects interfering with the airflow.

It's still apparent wind. If you are moving 5mph into a 10mph wind, you will register 15mph. The actual speed of the wind is a curiosity to me only. I know when it's too windy. Look at the tops and size of waves. Are they white capped?

[seahouse]

As Russ points out, the masthead position is more likely to be in a clean, undisturbed airstream. The masthead position will also give a better indication of the relative wind direction, so the two instruments, often combined, are both located there conveniently at the same time.

Assuming both upper and lower windspeed measurements are taken in unimpeded and non backwinded locations, they will be equally accurate, but different, because friction with the surface causes the wind speed to be greater the higher the measurement is taken. By how much varies with how strong the winds are (and a few other things). Which is why sails must be twisted to get maximum power, as I mentioned in another recent post.

You will notice that a gust leads higher up, so it will hit the top of the sail before it hits the lower parts of the boat. It's most notable if you watch the ripples on the water, the boat will heel well before the ripples reach the hull. It's magical, almost like witchcraft.

By “accurate”, it means it is a reading very close to the actual wind speed at that particular location, so that also varies with the instrument used. The cup-type is non-directional and very sensitive in low-wind conditions. Just this evening it was dead calm (heat wave on here now ) and we could feel no perceptable wind, and yet the cups on the (ground-based) anemometer were still turning very slowly.