Why anemometers

jwing

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Jun 5, 2014
503
ODay Mariner Guntersville
A thread regarding a non-working anemometer inspired this question: What is the purpose of knowing the wind speed at the masthead?

I've sailed the Caribbean from the Florida Keys to Grenada, but none of the boats had wind speed devices and it never occurred to me to want to know wind knots. However, I have decided to concentrate on improving my sailing skills - how might an anemometer help me?
 
Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
True wind speed and direction, VMG, etc... More info never hurts.
The Polynesians managed to cross oceans without even a sextant but I'm not that good.
 

jwing

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Jun 5, 2014
503
ODay Mariner Guntersville
How does a masthead anemometer determine true windspeed and direction and what good is that knowledge to me at the helm?
 
Nov 6, 2006
9,885
Hunter 34 Mandeville Louisiana
Most of the folks who use them are using them to make decisions about which sails to use.. and when to reef etc.. performance decisions.. folks who don't race tend to not use them. Very useful for night sailing too when you can't see the normal sensory input.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
it will let you know when its time to reef and also help keep you out of the Irons...but there are other ways to do this ......
 
Oct 9, 2008
1,739
Bristol 29.9 Dana Point
Wind direction is useful to know at a glance if it has changed, confirming any suspicion should I hear or feel the sails change. And without moving my butt.
Have a windex too but requires peering around the bimini.
Wind apparent speed helps in the total analysis of sail trim, boat speed, etc. it's a consistent reference point to compare with the others, even if the consistent reading is not true wind or direction. -although you can math it out to discover true, I see no need in local day sailing. I used to have to guess at wind speed, and it's nice to know the data.
Previous boats didn't have wind speed, and I seemed to sail fine without it.
 
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Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
How does a masthead anemometer determine true windspeed and direction and what good is that knowledge to me at the helm?
Apparent wind changes with heading and boat speed.
Assuming an anemometer interconnected with knot meter, it compensates for speed and direction to give real data useful in making course management decisions useful in both racing and cruising.
Having cruised the same areas you mentioned, my recollection is that most boats had one; some two.
 
Feb 14, 2014
7,400
Hunter 430 Waveland, MS
With todays modern electronics and displays, I can get a display wind vector (arrow length proportional to speed) and direction by vane. Thus a better forecast of my navigation, tacking, shallow water avoidance and plot my course. This is a racing advantage, safety, and perhaps more fun than value.

The Polynesians managed to cross oceans without even a sextant but I'm not that good.
I wonder what percent of them DIDN'T make it.

Mine is on the blink, so I bought a handheld cheapy. I used it 3 times during Memorial Day week end. :rolleyes:

By the wind speed and direction I could do a ETA on my target. ETA was 4 hours, Admirals says, tide will be wrong and sunsets in 3. Hmmmmm so I added an engine boost and got home in 1.5 hours. Admiral was happy.

So add Bliss to the list of benefits.
Jim...
 

druid

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Apr 22, 2009
837
Ontario 32 Pender Harbour
I've never had a windspeed indication. I have a windvane at the masthead that's VERY useful, especially when trying to get to that upwind anchorage (as long as a fat-assed eagle doesn't park his fat ass on it and break it!). If you don't know when to reef based on how much heel and how hard it is to steer, you should learn. ;)

About all the windspeed indicator is good for is bragging rights: "I was out in 35-40 last weekend", "I can carry full sails in 15 knots...", and so on.

druid
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
I've never had a windspeed indication. I have a windvane at the masthead that's VERY useful, especially when trying to get to that upwind anchorage (as long as a fat-assed eagle doesn't park his fat ass on it and break it!). If you don't know when to reef based on how much heel and how hard it is to steer, you should learn. ;)

About all the windspeed indicator is good for is bragging rights: "I was out in 35-40 last weekend", "I can carry full sails in 15 knots...", and so on.
druid
LOL ! "Bragging rights". I was going to say the same thing. BTW, I was out in 20kts last weekend. My Hunter has an anemometer ;)
When it's white capping, it's time to reduce sail.
 
Sep 25, 2008
1,096
CS 30 Toronto
Wind instrument give you indication how high (close haul) can you go without loosing speed. VMG to wind help to know how efficient your sail trim is.
You don't have to use it just like people don't look at the dashboard in the car while driving even in the dark.
You can sail with nothing but I like toys.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
Without an anemometer, how will the National Hurricane service know when to "Name a Storm" and invalidate my insurance coverage.:doh:
Jim...
that storm of yesterday has pushed a lot of water into the bay here making unusual high tides even with the wind coming out of the north west totally adverse to what it should be
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
Without an anemometer, how will the National Hurricane service know when to "Name a Storm" and invalidate my insurance coverage.:doh:
Jim...
Good point. I think cancellation correlates with the wind ripping the vane from the mast
 
Jan 6, 2010
1,520
The only thing I believe is:

"The prudent navigator should NEVER rely on only one form of navigation." It's in the course for a reason.

Aside of my electronics & boat/tablet/GPS/laptop/maybe smart cell phone etc., I still keep a bearing compass, paper charts & sextants for taking sun & moon shots. I have had to use these in the past when all else failed...........

Just something to keep in mind plus, we really only fly sideways & I like to know what the wind is doing to my sails......up & down the whole way and, I outpace most boats.

CR
 

kito

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Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
For $40 you can get one of those cool looking anemometer that plug into your smart phone. Too bad I am still using a flip phone ;)
 
Oct 26, 2008
6,045
Catalina 320 Barnegat, NJ
If you have sailed for years without one, I doubt a wind speed instrument will help improve your sailing skills, particularly if you don't integrate it with a speed sensor (which you have to do in order to derive true wind direction and speed). Nevertheless, it is a useful instrument. I don't rely on it, but I much prefer to have it. It's more useful to me than a speed instrument or even GPS. You can interconnect with your autopilot and let the boat steer to your sail trim, or, as I do, let Sue steer to the sail trim. I'll tell her something like, keep that needle on 60 degrees and we'll be fine. I set the sails and we go. No muss, no fuss. Sue doesn't have to crane her neck looking at the top of the mast. Who does like looking at a wind vane at the top of the mast, anyway? You go blind looking directly into the sun and you break your neck at the same time!
 
Sep 20, 2014
1,320
Rob Legg RL24 Chain O'Lakes
I need to buy one. What it will help me judge is comparing forecast and the National Weather Service to reality. It always much more windy out on the water, so it would be nice to predict that difference before going out. Where I primarily sail, one can not see the lake from the launch ramp, so it would be nice to predict the conditions ahead of time. I don't mind sailing in 30 mph winds, but I do mind doing it alone.

BTY: Why bother with a wind vane at the top of the mast. I use telltails attached to the stays. Easy to see, and works just fine. I have found that for durability, strips from a Menard plastic bag works very well. Even withstands 80mph+ winds on the freeway.
 
Feb 2, 2006
464
Hunter Legend 35 Kingston
I do a fair bit of night sailing and racing and find the direction feature very valuable for keep a tight close hauled course or sailing safely near dead downwind (avoid an unexpected gybe) when it's dark. While a windex is invaluable, it requires you looking up regularly. With instruments mounted in front of you, it's very easy to do regular quick checks of your course relative to the wind. while still keeping you eyes forward on the horizon or sails.

When racing in very light conditions a night, where there is little to no boat "feel", the instruments can be the first clue that the 2 knot breeze has shifted 180 degrees (or whatever). Paying attention (with the help of instruments) has paid off for me many times. In drifter conditions, often a "new wind" will come in from a new direction with a touch more pressure. If you can detect that first, you can make big gains.

As other posters have noted, wind instruments are helpful for know when to change sails. Again, when racing, you want to push your spinnaker to the limit, but not much further!

If you have a full instrument set, your wind instruments will connect to your other instruments and your autopilot. This often allows your autopilot to sail to a point of sail.

Cheers
Chris