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Old 2nd July 2011, 08:23 AM   #1
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Question Beaufort Scale

It was mentioned in another thread that the Beaufort Scale is outdated. Perhaps it is to some but it still serves its purpose because not everyone has an anemometer with him when windsurfing. It indicates a range of wind speed using observable phenomena on sea and on land. Personally, I've heard "experienced" windsurfer estimating wind speed to be 30 knots when it was only 15-20 knots :-p

Units of measurements are so different in different countries! Some measure weight in stones, temperature in degree F, distance in miles, speed in miles/hour. Wind speed is measured in knots which most people are not familiar with. Yes, if only this world could agree on an international standard. { Should we all drive on the right or left side of the road? ;-). I'm glad that board volume is measured in liter and not gallon, sail size is in meter square and not square foot.

"The Beaufort Wind Scale was created by Sir Francis Beaufort so that wind speed could be measured on a standard scale, making it possible for sailors to communicate with each other more objectively about wind speeds." Beaufort Scale, has not been used by the UK met office some years ago because many people don't understand what it represents.

Should windsurfers use the same unit of measurement for board speed and wind speed?
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Old 2nd July 2011, 10:40 PM   #2
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We use what is most commonly used in our area, but I think knots is probably the most recognized wind measurement world wide.

I live in the US and there are thousands of anemometers at airports, marinas and iwindsurf.com locations for us to check before heading to the water. Most in MPH, and some in knots, but I think most US sailors can convert MPH to knots in their heads with reasonable accuracy. When most of us in the US say it's blowing 20 knots, you can be sure that that's observed or estimated based on multiple area reading.

No reason not to be as precise as possible.

I don't see Beaufort used often, so I don't have any idea about the conversion to something I know, so I would have to look it up like the majority of windsurfers (just a guess).

I think knots for wind speed and water craft speed is the standard for all things nautical, at least for most of the world (inland lakes in the US may be an exception).

I am glad that windsurfing is in the metric system, I just wish the US government would also convert. Too many politicians afraid to make waves. As they say "Just Do It".
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Old 3rd July 2011, 07:07 PM   #3
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I too was concerned with comments dismissing beaufort scale, but like normal I suspect its got lots to do with where you sail.
Having the experience to look out to sea and rig correct sail is a skill not to be undervalued. Using an anerometer is at best a guide and at worst totally misleading.There are many pitfalls relying on anerometer readings.. Wind at sea is rarely as found on beach ;probably near cliffs;hills or trees. Wind increases at top of cliffs when onshore and wind at height bares little resemblence to that at sea level.
I find wind speeds abroad (ie in warm climates) have to be at 3 or 4 mph higher than home for similar power.Cold air is denser; a modern ICE engine can not rely on a simple air flow metre, it needs air mass sensors (ie takes temperature and hence density into account) An anerometer can do no such thing.

The beaufort scale on the other hand is totally based on the wind`s effects on the sea which is much more useful than simple airspeed.Denser air will have more effect on seastate.Its the better guide.There is rarely a day with a constant wind;Beaufort has this covered.It gives a likely range of windspeeds having similar effects on sea state.Might be old be certainly far from outdated.IMO its gives much more meaning than simple windspeed; but its designed to be "subjective" and given from looking at sea state and not direct from an anerometer.Thats the whole point.Converting to Beaufort is pointless.

I can not accurately guess airspeed but I never try to. I look at sea conditions and decide on sail size from that. A flat sea;offshore wind;little chop results in a larger sail than less air speed;rough water big waves.

The beaufort is something we can all understand; it serves its purpose perfectly. I stopped trying to use anerometer years ago but its something we all have to go through. On lakes; flat water making a choice between 10 metre and 11 well fair enough but thats a decision I never have to make.
Assuming we all need or would benefit from an accurate knowledge of windspeeds and which sail to use is fundamently an error. Windspeed is only one aspect of many variables when choosing sail size. The prescriptive method mentioned on other thread would not work for me.

PS I use mixture of beaufort and knots ??? Never use metric or mph ??? Has led to confusion when abroad (Europe) where KMH is standard unit but on a scientific note the SI unit of speed is metres per second; which I would never dream of using.
Admiral Beaufort did a splendid job. If it aint broke dont mend it..

We all love F5 sailing; we all know exactly what that means whatever sail we choose for F5..

Last edited by Floyd; 4th July 2011 at 04:54 PM.
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Old 4th July 2011, 04:51 AM   #4
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Floyd,

After my post, I checked on the Beaufort scale and now I may reconsider my thinking. Since the wind is never constant, but always changing speed, it makes more sense to use a scale that expresses a range rather than a specific speed (unless the actual range is split between two Beaufort numbers).

The hard part is adapting to a new scale and since no one around where I live thinks or expresses the wind in Beaufort, I would be on my own.

On the other hand, saying the wind is blowing 5 Beaufort or 16 to 21 knots doesn't seem much different., except that I would have to carry a chart with me until I learned the Beaufort scale.

The most recognized international nautical wind speed measurement is knots. I guess I will stick with it.

Checking the various local sources for wind speed only does one thing, do I go to the lake or do I stay home. There is a gray area when the wind is on the light side where I either have to rig big on my formula board, or possibly slog around for a high percentage of time on the same rig (3 Beaufort). If the wind is clearly over 3, then the day will be good, but I won't know what board or what sail until I see the water and check with the guys already on the water.

Right now and for the foreseeable feature, it's 1-3 Beaufort. Bummer.
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Old 4th July 2011, 08:40 PM   #5
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Imho I don't find so difficult to have an idea of the knots of winds blowing. Knots are related to speed and nowaday we all live with the car speed, the bike speed, the boat speed, etc.
Yes we can do wrong evaluations, so I always keep in my car a good "tower-shape" anemometer, I mean omnidirectional. And THEN I correct the results with simple observations, sometime with a small telescope, just to see if otside on the sea or lake seems to be more or less windy. And obviously asking to other riders the sail they're using AND their weight, if it's someone around windsurfing (rare in Venice Lagoon...).
Beaufort scale reminds me the (in)famous Mercalli scale used in Italy for earthquake, based like the Beafourt one on direct observations of the EFFECTS, not checking the stenght of the eartquake. The result is that italian earthquakes are higher in scale compared to the last Japan terrible ones!!! Yes we have ancient houses not exactly quakeproof...
I mean, a scale based on the effects is imho wrong because it depends on the type of building, threes, earth, sand you find.
Right last time I've (tried to) make wave-windsurfing I made the mistake paying too much attention to the flying sands, thinking at this like a sign of very strong wind; but the Sottomarina beach is very wide and full of dunes, so sand is prone to fly with far less wind strenght that, f.e. a flat hard beach like in Roemoe (DK). The result was a totally frustrating session underpowered with 4,5, when the rider with the car parked next to mine (75 kg vs mine 90 kg...) had rigged a 5,3 and enjoied the day a lot! I'd have to listen to my anemometer, showing really 20 knots on the beach at its best, yes in the sea pheraphs the average was more, steady 20-22, but absolutely not the 25 to lift up that heavy butt of mine...
Trees: what kind of trees? There are threes with leafs heavy and hard to move, and other trees with leafs moving everytime you sneeze nearby... Italian ancient roofs loosing pieces with 20 knots and modern strong roofs that can bear 50 knots with no sign....
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Old 5th July 2011, 12:30 AM   #6
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Ken

The Beaufort scale is more an indicator of "conditions" than simple wind speed. To my mind that makes it more usefull . Use of knots I think you`ll find (historically) was (is?) more likely to be used for boat speed. (its where the term derives from;knots in a measuring rope at set distances apart) Sailors wouldnt give wind speed in knots they would refer to Beaufort.???

When we are discussing wind speed we have started to talk of 5 metre (or such) weather which again is more descriptive but its a personal subjective measure. (My 5 metre weather is totally different to daughter`s but getting closer ???) But if a sailor says its 5 metre weather I know what he means !!!

In UK I`ve never heard a sailor refer to windspeed in Km/h ;m/s ;occasionnally mph or knots we nearly always use Beaufort or sail size ??? (even more confusing; 6 metre weather or F6 weather ???. The different language is all part of the sport ???)

My mates who race cars always talk in m/s ;where`s that come from ???I havent got a clue in m/s but Dutch/German lads in Canaries also use m/s ????

What about ;
no wind; a bit windy;windy; very windy; blowing a gale; dont bother ??? that works too !!!

Few years ago I went to Jamaica in November , knowing I`d be coming back in January. Asked fishermen on beach if it would be windy on my return.
" No man; no wind then." from all of them.
Came back in January (with no kit) and on beach there was a perfect F5 cross shore with nice waves every day for 3 weeks !!! Asked same fishermen what was going on ?
"This aint wind man; this is just a breeze;Christmas breeze, come back in August for wind"

August is hurricane season.!!! The Jamaicans have a different perspective after Katrina !!!

PS Just read Nakaniko`s comments.
You are right; looking a trees in winter gives a different windspeed to that in Spring(leaves,buds;water content etc) Sand on beach is correct too. Damp/dry/exposed but its a good "estimate" and I`ve found better than anerometer. Bearing was going on mine; would be blowing 35 knots but reading 25 ??? Effects on the sea however are pretty constant but not perfect. Allowance must be made for wind against or with tide which will alter effects it has.. All part of experience.. I dont use anerometer...New fangled gadgets !!! Stick my finger in air and rig a 6... You never really know til you get out ????

PS Easy conversion
knots to mph add 10% (50 knots is about 55 mph)

mph to knots Knock off 10%. (30 mph is about 27 knots)

Last edited by Floyd; 5th July 2011 at 12:42 AM.
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Old 5th July 2011, 04:20 AM   #7
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Ken,
You really dont want metric things.
Miles, pints and 45 gallon oil drums are how it should be.
Us limeys tried it and it never really caught on.
I think some wankers in europe dreamt it up and look at the state of that place.
Stick with what you know !
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Old 5th July 2011, 04:44 AM   #8
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Sorry Floyd, I have to disagree on this one.

I've used a very long time the scale of Beaufort.
Actually, when there was no windguru, windfinder or internet available, it was the only scale I knew.
On Teletext we could find in the early days only wind reports in Beaufort.
Those days, the times that I stould on the beach and on the water with the wrong sail, cursing myself, were countless.

Now it rarely happens to me, because I've learned a very important lesson: "to measure is to know"
Don't trust you eyes nor the wind reports, only your anemometer !

I agree that you cannot alway measure from the beach the exact wind force further on the water, especially off-shore or when there are obstacles, but that's another thing. I always try to find the best spot to do the measurements. This can sometimes be a completely different location than the location where I start surfing. I know, this is not always possible.

The things you see regarding the water state and wind force can be amazingly deceptive.
In general I would say, that with on-shore wind people tend to overestimate while with off-shore wind people tend to underestimate the wind force.
I've seen plenty of times a water state with no white caps, while it was F5 and on the contrary also plenty of white caps with hardly F4.
It can also depend on the weather, sun or clouds can make a lot of difference on the visibility of the water state and white caps.

Besides of this deception, for me there is quite a big difference between an average of 16 knots or an average of 21 knots, although both represent F5.
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Last edited by BelSkorpio; 5th July 2011 at 04:52 AM.
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Old 5th July 2011, 05:08 AM   #9
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Each to his own Belscorpio !!!

Found many issues with anerometers.(Take no notice of Windguru/Windfinder/coastguard current reports;generally they are worse than useless. We`ve been stood on beach in 5 knots (F1) with PC showing 15 and coastguard reporting similar on phone !!! The anerometer supplying Windguru at our loacl beach was broken for months yet Windguru continue to report current wind. (As did XC weather which used same equipment) There are issues in almost every direction.

Only really reliable way is to go out and see. Its often quicker than deliberating on beach !!!How long does it take to change down/up anyhow ??? (We often rig 2 sails straight away and leave one fastened to car)

Problem at our beach (most beaches ???) is wind is invariably better further out/south/north or somewhere. (We have a valley to south; cliffs to North and now a damned windfarm to south which has affected winds..
Anerometer gives wind on beach; we sail out to sea !!!

How often do you sail in a constant 16 knots ???? Suspect its probably by accident but Beaufort seems to cover the range within a force on a given day? Cant beat experience tho !!?? Thing isnt deciding on correct windspeed or correct Beaufort but correct sail ???
But if anerometer works for you ; fine.Mine stays in car now;with flat batteries and its iffy bearings !

Good sailing.

Last edited by Floyd; 5th July 2011 at 05:13 AM.
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Old 5th July 2011, 07:00 AM   #10
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Oh my! Am I completely off track? I have never consulted an anemometer, wind forecast, bulletin, or, as I have seen some people do while at the beach, any web-based instant-wind-speed gadget of sorts. I go to the beach, look and pick a sail and a board accordingly ... and never really go wrong. I have my reference points in terms of water conditions, wind lines (as Floyd mentions the wind here can be very different from the wind there, half a mile offshore), and overcast conditions and they work pretty well.

Back to the original question, what I think happens often is that people inflate wind-speed. You hear tales of 50 knots wind (e.g. one of the last PWA events) when overall conditions seem very far from "uprooting trees and not being able to walk". Maybe people do not realize how strong a gale is "just" 30 knots!!!

Last edited by davide; 5th July 2011 at 07:07 AM.
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