View Full Version : Beaufort Scale

2nd July 2011, 07:23 AM
It was mentioned in another thread that the Beaufort Scale is outdated.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?

2nd July 2011, 09:40 PM
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".

3rd July 2011, 06:07 PM
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..

4th July 2011, 03:51 AM

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.

4th July 2011, 07:40 PM
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....

4th July 2011, 11:30 PM

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)

5th July 2011, 03:20 AM
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 !

5th July 2011, 03:44 AM
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.

5th July 2011, 04:08 AM
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.

5th July 2011, 06:00 AM
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!!!

5th July 2011, 12:19 PM
It makes sense to consult the weather people prior to a long drive to the beach.
Other than that, you all seem to have truck loads of kit so as Davide says, go to beach, look and rig up.
I cant inmagine anybody rigging up based on what Bob Gates is telling them on the interweb.

5th July 2011, 04:36 PM
Never hear of anyone using this scale where i sail in oz, mostly knots is used. We look at water state and how much sand is being moved. A rough guide is when there is light water mist its 45kts and when its easy to see its 50-60kt. And yes we see this about every 4 yrs and its FUN with a 5.0

5th July 2011, 08:19 PM

Is it just the UK and US that are left and still stuck with a measuring system from the ancient world?

Full immersion for a few months and it's done. The US has been slooooooooooooly moving in the metric direction for what - 30 years? It's politics, no one want to be the "bad guy" that made us go all the way. Why not get with the rest of the world and go metric (except for knots on the water)?

5th July 2011, 11:46 PM
Ken, you may be surprised but km/h or m/s don't make sense here in France. Between windsurfers we rather talk knots and sometimes Beaufort. This scale is interesting because its captures wind variations to some extend. Now it may not match the conditions of the day. When the wind is very gusty average/max speed in knots is more representative. From the beach I always try to figure wind speed in knots and pick my sail accordingly. Then how do you measure knots without a rope or anemometer? I guess it comes with practice (and many errors).

6th July 2011, 12:00 AM

My comment was regarding the metric system in general, not just windsurfing. I use knots and MPH interchangeably for windsurfing, and I think we all use whatever is most common where we live. Nothing is right or wrong, just what works for you.

Experience teaches us how to read the water for wind speed, and it's pretty easy if you only sail in a few locations. It's all about fetch, wavelets, white caps and waves that helps us know what to rig. The hard part is anticipating what the wind will do an hour later. About 80% of the time, I make the right call regarding sail and board, but not always. I hate to re-rig, but it's better than slogging or getting blown away.

6th July 2011, 12:41 AM
Another reason why I want to know more precisely the wind force is the fact that I have rather (perhaps too) many sail sizes.
I mean, probably I would not be using an anemometer if I had only 3 sails, say 5.5, 7.0 and 8.5, which probably would also cover most of the wind range. In this case the scale of Beaufort would probably also be sufficient: F4,5,6. Never a dillemma, no worries. :)

But my sail range is: 5.0,5.7,6.7,7.8,8.8,11.0 and I want to have the ideal setup for a given wind force.

When I arrive at my favourite spot, the first thing I do is a wind speed measurement. I've got a windmaster 2 and I'm really happy with it. It indicates the current, average and max wind speed. I'm only interested in the average wind speed of course. Then I do some other things that keep me busy with everthing BUT rigging up the sail, because I want to postpone this as long as possible. E.g. I take out the board of the trailer, screw the fin, take out the boom, mast, sailbag, go to the toilets, etc..
The reason of this, is that I want to confirm my measurement, let's say 15 minutes later. If I get confirmation of approximately the same measurement as before (always average wind speed), I will rig up my sail accordingly. If there is too much difference, probably I will put on my neoprene first and do still a 3rd measurement afterwards. If this is again completely different, I get nuts :)
Then probably I will go to others to see and ask what they rig, I really hate to do this because then everything gets so subjective ...
Luckily, most of the times, I get after three measurements a really good indication.
I guess that all of this sounds a little bit freaky, but I know that I'm not the only one. :)

Oh yes, and there is also the psychological aspect of picking the sail size.
Only recently, when I was about to rig my sail, I saw an old windsurf buddy on the beach with all brand new slalom stuff.
I changed my sail for 1 size up. Why ? I just knew he was going to show off and do some fun drag racing with me. Too much testosteron, I know. Stupid, because afterwards I was too overpowered.
Another example is when I feel a little tired, I sometimes tend to rig 1 sail size smaller which I afterwards regret.

You see, picking a sail size can be one of the hardest things about windsurfing unless you stick to objective measurements.

6th July 2011, 03:15 PM
Well I don't use an anemometer but I also try to delay rigging until my perception is confirmed. When balancing between two sails, the bigger one is most often the best choice on a lake. Different story by the sea where it depends on many factors (onshore/offshore...) and evaluating the wind speed can be quite difficult.

6th July 2011, 03:44 PM

You make a difficult sport more complicated with your wind measurements!
Looking at your sail quivers, you have it covered from 7 knots (F3) to 25 knots (F6).

Wind conditions never stay constant. Even if you got the right sail when you started, you may find it either too big or too small when you are out on the water. May I suggest you try using the outhaul pulley system? It will make a big difference in your sailing. Modern sails have quite a big wind range and a good sailor must be able to adapt to changing conditions. Ben NED57 came in 2nd in Aruba using 1 board, 1 sail and 1 fin throughout the competition :-)

7th July 2011, 02:54 AM
You must have balls the size of an elephant to admit going through all that nonsense at the beach !!
You really need to throw more money at the sport.
Get more fins and boards to start with.
Sounds like you also need a quiver of Race sails.

7th July 2011, 02:57 AM
I am in somewhat the same boat as Belskorpio with lots of sails, but where I sail, there is a 100 meter wind shadow between shore and where the wind begins. No way to take a wind reading, so I have to do it by sight and I sometimes use binoculars to see what's happening a half mile from shore.

Also, all my sails from 6.6 to 11.0 have adjustable outhauls to maximize my adjust-ability. However, they aren't much of an advantage with the 6.6, somewhat with the 7.6 and 8.4, but a big advantage with the 9.2 and 11.0.

Since the winds are highly variable where I sail, I must pay attention to the gusts and not just the average. Average winds may be 20 knots, but a few sustained gusts of 30 can wipe out the forearms pretty quickly so I frequently rig a little small to be sure I don't get wasted too soon.

Life would be simpler with one board and three sails, but not as much fun.

7th July 2011, 03:43 AM
LOL :)
I expected a lot of funny reactions on my last post.

I've seen Ben VDS lots of time on my favourite spot in Holland.
Believe me, he's always on sails 1 - 2 m2 bigger as I am.
Typically when I'm on my 6.7, he's on his 8.6.
That's why he's a pro and I'm an amateur :)

On the Isonics I only use race sails.
And I agree with Ken, it's nice to have a big choice although life could be simpler.
To make this complicated choice much easier, I use an anemometer.
Winds change.Tell me something new. That's why I postpone the sail choice as long as possible. Logical, not ?

About throwing money at the sport.
At the moment I don't have any board nor sail that I've bought new. All 2nd hand.
But it's still expensive enough.

10th July 2011, 06:28 PM

It will be great if US and UK use the metric system like the rest of the world. However, human beings are reluctant to change. We are creatures of habits. If one grew up in an environment where imperial units were used, then metric will appear strange and vice versa. The older a person, the more difficult it is to change. Just getting the windsurfers of the world to use the same unit of measurement is impossible!

The great thing about the Beaufort Scale is that it is independent of the unit of measurement because the same wind force can be converted to m/h, m/s, km/h or knots.

(It is interesting to note that not all things nautical are measured in knots. F1 powerboats are measured in km/h or m/h.)

10th July 2011, 11:19 PM
I find it interesting that those that should know, frequently assume that mankind is not capable of changing/learning through immersion. We all can adapt very quickly if there is only one option.

In the US, especially Texas where the state and public school systems are confronted with a HUGE influx of non English speaking aliens. The schools almost all choose bi-lingual education (with poor results), rather than full immersion in English. You think educators would be smarter. Actually, the teachers are smarter, but it's the state and local governments that are not.

I still believe that it is politics that is driving this boat not results, same with the metric system.

I was out yesterday in Beaufort 3.5 with my formula board and 11.0 and hit a top speed of 23 knots.

17th July 2011, 01:59 AM
One reason why I prefer knots to Beaufort scale is the broad range covered by F4. At 11 knots I might be hardly planning with 7.8 mē - my biggest sail - while in consistent 15 knots plus gusts I may be happy with 6 mē and a small board. It is not the case in F5 or F6 where a single sail/board combo is more likely to cover the whole range. Of course I will pick one size that suits the average wind of the day, but F4 means virtually nothing although it is the sweetspot of many sailors.

17th July 2011, 05:48 PM
I agree with Farlo. F4 gives a general idea, but is not accurate enough for rigging.

17th July 2011, 11:54 PM
Today was typical "F4" weather. Forecast was 12 knots in the morning and 15 in the afternoon. Indeed when I arrived the wind was still moderate so I rigged my Naish GP 7.8 on the Falcon 112 and here we go. At some point the wind started to increase and I thought: well it's F4 rignt? Let's give a bit more outhaul to the sail. And just when everything was perfectly balanced... my wishbone broke!! Floating back to the shore I noticed a few guys much heavier than me with sub seven sails (admittedly they were not planing all the time). Then I rigged my Sprint 6.6 on another boom, took the ST104 and guess what: it was perfect day. Still F4 but steady 15 knots, a completely different kit and much more fun

17th July 2011, 11:56 PM
Couldn't agree more.
F4 is a very difficult and vague range, in which I could use 3 different sail sizes.

18th July 2011, 12:28 AM
10- 14 knots, with an average of 12 (F4) and gusts up to 17, and I'm probably on my 122/8.8 combo

13-15 knots, with an average of 14 (F4) and gusts up to 20 and I'm probably on my 122/7.8 or 101/7.8

13-17 knots, with an average of 15 (F4) and gusts up to 25 (which I had this morning) and I'm on my 101/6.7, a bit underpowered but always on the plane and going like crazy in the gusts

18th July 2011, 09:25 AM

Alternatively, you could simplify it into

F3-4: 122/8.8 combo

F4: 122/7.8 or 101/7.8

F5: 101/6.7, a bit underpowered but always on the plane and going like crazy in the gusts

Please note that for the poll F4 was not included. F4 conditions are a bit tricky because this is the minimum condition for heavier windsurfers to get planing but for the lighter windsurfers, they will be very nicely powered up in 6.6 - 7m

18th July 2011, 06:00 PM
I agree,

it all depends on how you define F4.

I merely want to point out once more that wind estimations, purely based on the visual, can be really deceptive. Yesterday, we had unbelievable wind variations, because of SW wind combined with a lot of showers. When I arrived at my spot, my first impression was 6Bft. Yes, there were gusts up to 25 knots, deluding the water state with magical white caps. But these were merely gusts. 80% of the time or more, the average was only 15 knots, sometimes dropping to hardly 12 knots.
I've seen a lot of guys shlogging in the lulls with too small sails 5.xm2.

18th July 2011, 10:56 PM
Hello Poster #29, again it depends on which F4 you are talking about. For sure I will be "nicely powered up in 6.6 - 7m" in steady 14-15 knots (I'm 67 Kg) but in 11-12 knots the 7.8 will not be too much. In "13-17 knots, with an average of 15 (F4) and gusts up to 25" I might be OK with 6m, but there is no single number like F4 to describe it.

18th July 2011, 11:41 PM
I tried the WindMeter iPhone app to make measurements but I quickly realized that measurements are far from the reality! I totally agree with Ken—experience teaches us how to read the water for wind speed, and it’s pretty easy if you only sail in a few locations.

When I’m on the beach and friends call to ask about the wind, I usually give them a beaufort estimation. That ends up being enough for them to decide if it’s worth the drive, or which sail to rig.

Just found an iPhone app called weendy that let me send a wind estimation out from the spot where I am sailing. That way everyone has the info, and I can finally rig my sail without all these phone calls: )