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Old 09-12-2009, 19:56   #46
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So what your saying is there is unwritten two Beaufort scales... one cold air and one warm.
Cold air also adds the disadvantage of being cold. Wet and cold can meet at hypothermia. Comfort is the better scale to measure by. I like to say what would you do on purpose? You sure can bet you'll get stuff you didn't plan on. At some point you have to bet on the forecast and lose even if you will win a few times too.

In sailing higher altitude is bad - always.
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Old 09-12-2009, 20:01   #47
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The forecast Force 7 was well within the capabilities of the boat but looking straight up the barrel of the gun with the wind funneling straight down Harwich Harbour and the Orwell river is the point at which I decided to turn back.
It's about what you would do on purpose if given a choice. Sometimes the do nothing choice really is easier than others.
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Old 09-12-2009, 20:08   #48
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How many time have we argued over how big the waves actually were or were not in certain rescue situations around here..regardless of what the wind was doing....
Precisely why Mr Beaufort developed his scale, the first revision of which didn't even mention wind speed but was relative to the amount of sail a man of war could carry.

The modern Beaufort scale we have today is a measure of sea state. Each increment of that scale does correlate to a range of windspeeds where those sea states may be encountered most often, but predominantly it is a measure of sea state.
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Old 09-12-2009, 20:18   #49
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Originally Posted by galleyslave View Post
Better stick to thinking in Beaufort rather than knots of wind. 35 knots with an ambient temperature of +5 degrees C is a very different animal from a summer blow with an ambient temperature of around 25 - 30 degrees C. The Beaufort scale tells you the effect the wind has and is a better guide.
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This confuses me...Other then obviously wind chill... what does temperature have to do with the Beaufort scale and it interpolations on sea state?
Just asking out of ignorance here..
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Sorry, I didn't express myself too well. I had just got up and was still in need of the first cup of coffee.

What is of concern in a sailing vessel is the amount of energy in the wind, some of which is, of course, captured to make the boat move. Wind energy has two components, mass which is dependent on temperature (the colder the air the greater the mass) and velocity. When you reduce sail, you reduce the volume of air, and by extension, the total amount of energy captured which is WHY you reef.
Can't really ring in on the discussion too much, but I can tell you that the temperature of the air makes a big difference in the take off distances and the efficiency of flight (aerofoil) in airplanes. Attached is a take off distance chart as it relates to temperature and elevation for a Cessna 172. Weight (and elevation) aside this is due the Density of the air caused (in part) by temperature which I suspect is what galleyslave meant when he said "mass"?
And so with colder air, I can see it having more (perhaps much more) influence on the water at the same wind speed.

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Old 09-12-2009, 20:20   #50
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Precisely why Mr Beaufort developed his scale, the first revision of which didn't even mention wind speed but was relative to the amount of sail a man of war could carry.

The modern Beaufort scale we have today is a measure of sea state. Each increment of that scale does correlate to a range of windspeeds where those sea states may be encountered most often, but predominantly it is a measure of sea state.
That makes the most sense so far...

OK then...Here in Puget sound then I like force 1 sea state and force 7 and 8 winds the best... for a good time out on the water sailing.....

Seems the system works best giving one for each entity..


An example..."We were getting blasted with force 9 winds in force 7 seas"
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Old 09-12-2009, 20:28   #51
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The modern Beaufort scale we have today is a measure of sea state. Each increment of that scale does correlate to a range of windspeeds where those sea states may be encountered most often, but predominantly it is a measure of sea state.
That is not conveyed very well in any of the charts that explain the scale as they usually list a wind speed first. I can understand using a standard terminology to describe the sea state. That makes sense because it is hard to describe. My objection come from having a separate terminology to describe wind speed which can be quantified and conveyed to the listener easier by the number of knots then a Force number that describes a range.

I still don't know what to do if the wind if force 5 and the sea state is force 6 or 7. How does the scale help you in that case? Wouldn't me telling you I was in 25 knots of wind and 4 foot seas be more descriptive and convey all the information you need to get a good mental picture. If I was to say 50 knot winds and 4 foot seas it couldn't be described by the scale and yet you can picture what I was experiencing pretty easy without it.

I don't want to belabor it because it is certainly of little importance but I hate to see professions (including my own) develop languages, codes, words, scales, etc that are only understood by those with training in the specialty and carry no benefit except to obscure the information from those not in the club.

[Stepping off of soapbox now]

Jim
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Old 09-12-2009, 20:45   #52
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Jim your a saint..God bless ya man!.....way better put then all the staggering around the deck that I'v been doing.
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Old 09-12-2009, 21:17   #53
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I hate to see professions (including my own) develop languages, codes, words, scales, etc that are only understood by those with training in the specialty and carry no benefit except to obscure the information from those not in the club.

[Stepping off of soapbox now]

Jim

I truly believe that the Beaufort scale is doing the exact opposite. It is a great way of transfering a great deal of approximate information quickly, eg:

NE 4 / 5 OCNL 6 later

This is a huge amount of information presented in a concise manner. We could dilute it into wave heights, frequencies, water and air temperatures, wind speeds etc etc. but I don't think it would add anything to our understanding.

NE 4 / 5 OCNL 6 later tells me I'm going to have a good sail today and I'll be reefing later. I can make all the decisions I need to based on this. Having more detailed information does not add anything to my understanding, nor my decision making.
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Old 09-12-2009, 21:28   #54
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My punt is 'waves kill ships, not wind'. So focus more on waves, their shape, where they are coming from, and how that may change along your route.

My lightweight handles up to 40 kts on a close reach, reach & run, so your boat should handle up to force 8 quite comfortably if handled well. But going close hauled in 40 kts is something else entirely, a few hours is much easier than a few days, slower is easier than faster (sometimes), and at some point on the Beaufort Scale you start avoiding areas of confused seas and avoiding going beam on.

I quite enjoy surfing under a storm jib, but not so much in big, breaking waves.

At the end of the day what we choose to go out in comes down to skills (skipper & crew), comfort (skipper & crew), and susceptibillity to motion sickness (skipper & crew). So you always get a wide range of answers to this sort of question.
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Old 09-12-2009, 22:07   #55
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I truly believe that the Beaufort scale is doing the exact opposite. It is a great way of transfering a great deal of approximate information quickly, eg:

NE 4 / 5 OCNL 6 later

This is a huge amount of information presented in a concise manner. We could dilute it into wave heights, frequencies, water and air temperatures, wind speeds etc etc. but I don't think it would add anything to our understanding.

NE 4 / 5 OCNL 6 later tells me I'm going to have a good sail today and I'll be reefing later. I can make all the decisions I need to based on this. Having more detailed information does not add anything to my understanding, nor my decision making.
Yes it would appear to but for the laymen unfamiliar with a particular area it can be very misleading indeed and quite dangourous...S/V Jedi put it best.

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So that makes it the combination with the sea, which directly means that it is always that combination. An example: a force 8 on the Atlantic is fine, but a force 8 on the North Sea or even the Caribbean is a different story.
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Old 09-12-2009, 23:29   #56
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My apologies for the enforced absence - monkeys practicing slack wire dancing on the telephone lines or similar.

To repeat, Beaufort gives you a means of judging the energy gathered by your sails by observation of the state of the sea.

Wind energy has 2 components, mass and velocity. To observe the same effect, there can be a diminuition of one of the components providing there is a corresponding increase in the other.

Drop a musket ball on your bare foot from waist high and you will probably just say 'Ouch', rub your foot and carry on. If you drop a cannon ball onto your bare foot from the same hight, you will have a big problem. The speed at which both balls hit your foot will be the same, the difference will be the mass and thus the energy transfered to your foot. To get the same reaction from the cannon ball hitting your foot as the musket ball, you will have to go to less than an inch of drop and correspondingly much reduced velocity. Conversely, you would have to go very high to drop the musket ball to do a similar amount of damage. The Beaufort equivalent would be the amount of discomfort you observe, the information you are looking for is the amount of damage. There is a rough correlation between damage and pain.
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Old 09-12-2009, 23:34   #57
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Seeing that I don't have a knotmeter or a wind speed indicator on my boat, the old descriptions of the Beaufort are quite useful and I can then transfer that back into knots if i need to. Sure it's approximate, but I care much more about getting a feel for the seas than knowing a knot-accurate sea state.

look for wave, whitecap, spray, foam, streaking foam, etc.

Plus, they correspond to the various warnings. Force 5-6 meaning "small craft advisory", etc.

Here is the scale from bottom to top. I haven't memorized all of it because I rarely care about the extreme ends, but the middle of the scale from 3-8 is very useful.

  • Force | At Sea | On Land
  • Force 0 "calm" | Flat |Calm. Smoke rises vertically
  • Force 1 "light air" | Ripples without crests | Wind motion visible in smoke.
  • Force 2 "light breeze" | Small wavelets. Crests of glassy appearance, not breaking | Wind felt on exposed skin. Leaves rustle.
  • Force 3 "gentle breeze"| Large wavelets. Crests begin to break; scattered whitecaps | Leaves and smaller twigs in constant motion.
  • Force 4 "moderate breeze" | Small waves with breaking crests. Fairly frequent white horses. | Dust and loose paper raised. Small branches begin to move.
  • Force 5 "fresh breeze" | Moderate waves of some length. Many white horses. Small amounts of spray. | Branches of a moderate size move. Small trees begin to sway.
  • Force 6 "strong breeze" | Long waves begin to form. White foam crests are very frequent. Some airborne spray is present | Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over.
  • Force 7 "high wind, near gale" | Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray. | Whole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors.
  • Force 8 "gale" | Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray. | Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded.
  • Force 9 "strong gale" | High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility. | Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies.
  • Force 10 "storm ,whole gale" | Very high waves with overhanging crests. Large patches of foam from wave crests give the sea a white appearance. Considerable tumbling of waves with heavy impact. Large amounts of airborne spray reduce visibility. | Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs.
  • Force 11 "violent storm" | Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility. Widespread damage to vegetation. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely.
  • Force 12 "hurricane force" | Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility. | Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about.
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Old 09-12-2009, 23:38   #58
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Yes it would appear to but for the laymen unfamiliar with a particular area it can be very misleading indeed and quite dangourous
With all due respect, it's not intended for the layman

It is intended to convey information to a competant sailor to apply to the particular stretch of water in which he/she will be sailing and the particular vessel that he/she is on.

I don't think there is a better global system than the Beaufort Scale for doing that.

I must confess though that the first thing I do when I get a forecast in Beaufort is convert it to windspeed in knots in my head and then figure out possible sail configurations from there.....
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Old 10-12-2009, 00:23   #59
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With all due respect, it's not intended for the layman

It is intended to convey information to a competant sailor to apply to the particular stretch of water in which he/she will be sailing and the particular vessel that he/she is on.

I don't think there is a better global system than the Beaufort Scale for doing that.

I must confess though that the first thing I do when I get a forecast in Beaufort is convert it to windspeed in knots in my head and then figure out possible sail configurations from there.....
Point taken
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Old 10-12-2009, 06:47   #60
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Seeing that I don't have a knotmeter or a wind speed indicator on my boat, the old descriptions of the Beaufort are quite useful and I can then transfer that back into knots if i need to. Sure it's approximate, but I care much more about getting a feel for the seas than knowing a knot-accurate sea state.

look for wave, whitecap, spray, foam, streaking foam, etc.

Plus, they correspond to the various warnings. Force 5-6 meaning "small craft advisory", etc.

Here is the scale from bottom to top. I haven't memorized all of it because I rarely care about the extreme ends, but the middle of the scale from 3-8 is very useful.
If that was how the scale was described I could agree it would be moderately useful. Unfortunately every scale I could find on the internet and the Annapolis Book of Seamanship starts with the wind speed range not the sea state. What the people in this discussion who use the scale are saying is ignore the wind speed and just use the force numbers to describe what you are seeing. That makes some sense. It does not make sense to me though in it's current written form as it tries to describe 2 things (wind speed and sea state) and bring them together when in real life they may not be related enough to do that.
One discussant mentioned that this is not for layman. Don't we all get a little ticked off reading a legal document that has to be "translated" for anyone other then a lawyer or talking to a doctor and not understanding a word they say. If you are using the Beaufort scale in a way that would "seem" non standard (ignoring wind speed measurements) and talking to a group of non-professional sailors it might have the same effect as the above mentioned cases.

Whereas the party of the second part hereby concludes that the party of the first part was not incorrect when making aforementioned statements and the party of the second part acknowledges their own inadequacy at deciphering the scale mentioned in the attachments, let it be known that the party of the second part regrets making certain statements that might have been construed to mean something to the party of the first part other then the intended meaning of the party of the second part and will hereby belay making statements similar to the above referenced statements now and in the future.

Or, I am sorry I said anything and will never do it again.

Jim
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