Old age or weather conditions
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Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=11899
Printed Date: 09 Jul 25 at 10:55pm Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Old age or weather conditions
Posted By: Steve411
Subject: Old age or weather conditions
Date Posted: 23 Feb 15 at 8:56am
Sailing yesterday seemed really hard work. It was windy, but not excessively so - max gust of 27 knots with the average about 20 or so. The thing is it felt a lot windier with really heavy sheet loads. Now, it could be that I'm just getting weak in my old age, but someone at the club suggested it was due to the weight of moisture in the air - it was raining very heavily the whole day. It sounds reasonable that this could create heavier sheet loads but is it correct?
------------- Steve B
RS300 411
https://www.facebook.com/groups/55859303803" rel="nofollow - RS300 page
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Replies:
Posted By: turnturtle
Date Posted: 23 Feb 15 at 9:03am
Nope.... it's just mother nature telling you to buy a Solo.
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Posted By: Woodbotherer
Date Posted: 23 Feb 15 at 9:09am
They were pretty heavy gusts coming down, it's often like that ahead of a front. Got to our lake first thing, nothing, by the time the buoys were out and the five sounded it was a reasonable breeze maybe two, then as the race progressed it got puffier and puffier exactly as the forecast had predicted, ended up having me in irons up the last beat and today I can hardly walk, but it was a moral victory I managed to hold on to a 2nd place all the way around until onshore when a nasty corrected time gust sent me from 2nd to last..
------------- http://www.edgeactionsports.co.uk/collections/soundcast-portable-weatherproof" rel="nofollow - Soundcast Weatherproof Speakers
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Posted By: Steve411
Date Posted: 23 Feb 15 at 9:18am
Originally posted by Woodbotherer
They were pretty heavy gusts coming down, it's often like that ahead of a front. Got to our lake first thing, nothing, by the time the buoys were out and the five sounded it was a reasonable breeze maybe two, then as the race progressed it got puffier and puffier exactly as the forecast had predicted, ended up having me in irons up the last beat and today I can hardly walk, but it was a moral victory I managed to hold on to a 2nd place all the way around until onshore when a nasty corrected time gust sent me from 2nd to last.. |
Conditions exactly the same at our place.
------------- Steve B
RS300 411
https://www.facebook.com/groups/55859303803" rel="nofollow - RS300 page
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Posted By: Woodbotherer
Date Posted: 23 Feb 15 at 9:55am
As to your original assertion we often have this discussion on the windsurfing forum about wind density and sail sizes, given we can all hold up a bigger sail in a given windspeed in say Egypt than the cold water vapour laden air we get here when a front approaches. It's obviously more apparent to us hanging onto the boom direct, but it's exactly right what you said, it was tougher yesterday, I'm still struggling with the concept of sailing sheeted out using the kicker it's all a bit alien to me, but it certainly was the only way to survive towards the end of yesterdays race especially having a busted footstrap on one tack (the one I had to use more often naturally).
------------- http://www.edgeactionsports.co.uk/collections/soundcast-portable-weatherproof" rel="nofollow - Soundcast Weatherproof Speakers
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Posted By: Rupert
Date Posted: 23 Feb 15 at 10:41am
It does seem to be true that air in warm places has less "push" for the same speed. I think it is also that cold weather slows reaction times, that the buffeting wind is harder to handle, the rain stops us looking out as far, so we don't see the gusts as early, and yes, some of us aren't as strong as we used to be.
Really not gonna get a Solo, though. Topper, maybe...
------------- Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Posted By: boatshed
Date Posted: 23 Feb 15 at 11:10am
Air at 5 Deg C is about 3% - 4% denser than air at 20 Deg C
Which isn't that much. Equivalent to going from 10 knots to 10.4 knots.
It's probably the frequency and size of the gusts that is felt much more. I think the load on the sail generally increases by the square of the wind speed, so, going from 20 knots average to a 27 knot gust will be really be felt. Welcome to Winter sailing!
------------- Steve
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Posted By: Woodbotherer
Date Posted: 23 Feb 15 at 11:21am
Originally posted by Rupert
Really not gonna get a Solo, though. Topper, maybe...
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What about a Streaker Rupert? It keeps coming up Streaker on this lake, another one has appeared, one of the bandido bros had to use it because Pancho Villa now has a job guarding the nations shores on shiftwork, anyway he was making himself a right nuisance amongst the Lasers and just wouldn't get back down the back of the fleet where they belong...
------------- http://www.edgeactionsports.co.uk/collections/soundcast-portable-weatherproof" rel="nofollow - Soundcast Weatherproof Speakers
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Posted By: blaze720
Date Posted: 23 Feb 15 at 11:56am
Sunday am at Burghfield given forecast there was a reasonable turnout but the wind was getting progressively stronger. But very manageable really. It got a bit tougher towards the end as the front got closer with high levels of turbulent air down at the surface - so very rapid speed and direction changes. Dare I say it on this forum 'Blaze conditions' (but please do substitute for your favorate class if it likes a bit of breeze !).
Afternoon was a bit different ..... Very few starters in any class so the RO sensibly looking to save a few minutes started what remained of all classes together (well there was only one asymetric, one OK, no lasers and a handful of Blazes left). One in our midst has been doing the frostbite with his 'Fire' sail on Sunday afternoons and I'm joining in occasionally with one myself to learn more about how to get the best out of it. That was fortunate this time. Wind was by now lets say 'interesting' and 'out-to-get-you' plus much stronger in the gusts and prepared to take no prisoners if you made a slight mistake.
Fantastic fun ... Blaze-Fire reminds me of board racing in challenging conditons when you have the right gear - near constant planing both up and down wind ! Even so it was tough - A Blaze alongside even broke a lower in one severe gust. On another leg a near total dump of the kicker was required to be sure of keeping some token amount of control on a reach and get 'below' one of BSC's islands with certainty .. the other Fire ended up poking around in the bottom of the lake with his mast tip. Don't know the actual peak gust speeds but low 30's seemed realistic - but it was the speed of wind change that was the real challenge. Anyway the RO could see the way it was going and after less than 40 minutes finished the race ... with nobody complaining.
It always feels windier in winter imo - I don't think it is much to do with the relative density of the air though. The air however often seems more turbulent and winter clothing + lethagy just does make it seem toughter.
And yes ... I hobbled away afterwards on Sunday as well.
Mike L
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Posted By: transient
Date Posted: 23 Feb 15 at 12:14pm
I did some research into this, I noticed that for a given windspeed things could feel different, sometimes heavier sometimes lighter. The results were interesting:
Temperature effects air density: colder = denser (no surprises there)
Altitude: lower = denser (clearly)
Atmospheric pressure: Higher = denser (obviously)
but the surprise for me was moisture. I thought damper = denser but I was wrong, wrong, wrong.
Water at the molecular level weighs less than air by quite a margin
Moist air is lighter than dry air.
so the heaviest most powerful air is: High pressure, cold and dry.
edit......not sure what happens if there is solid water (rain drops) in the air though.
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Posted By: Woodbotherer
Date Posted: 23 Feb 15 at 12:41pm
I've read and had that described to me before, it was an argument made on the windsurfing forum, one just has to assume that as it's on the way back down then it has reverted to the level above molecular which sees water actually below air at surface level pressure or whatever physics it is that suggests moist air is lighter. Warm moist air I can see, but cold moist air, sorry that comes back down, so what is the science of that description and at what temperature was it detected?
------------- http://www.edgeactionsports.co.uk/collections/soundcast-portable-weatherproof" rel="nofollow - Soundcast Weatherproof Speakers
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Posted By: turnturtle
Date Posted: 23 Feb 15 at 1:16pm
Originally posted by transient
edit......not sure what happens if there is solid water (rain drops) in the air though. |
your rig gets wet, therefore it's heavier to handle?
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Posted By: maxibuddah
Date Posted: 23 Feb 15 at 1:44pm
That and your hands are cold and wet so don't work as well, appearing to make things feel heavier too
------------- Everything I say is my opinion, honest
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Posted By: alstorer
Date Posted: 23 Feb 15 at 2:15pm
Ignoring rain for now (because I can't answer that) lets go basic science.
Very roughly, a given quantity of gas molecules will occupy a set volume, regardless of what those molecules are- the elements and compounds in air generally behave close to an idea gas, so at a pressure of 1 atmosphere (1000mB, 29.53 inches of mercury) 1 mole* of gas occupies 24.465 litres at 25°C- or 1 litre of air contains 0.04 moles of gas- approximately 80% of this is Nitrogen, with a molecular weight of 28, and 20% is Oxygen, with a molecular weight of 32. A water molecule has a molecular weight of 18. Up to 5% of local atmosphere can be water vapour.
What I'm not sure is how all this applies. regardless of gas composition or temperature, 1 Pascal of pressure is 1 newton of Force on 1 square metre of area.
*not small furry mammals. 6.02x10^23 atoms/molecules/other of a substance. A useful unit when doing chemistry.
------------- -_
Al
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Posted By: transient
Date Posted: 23 Feb 15 at 2:20pm
Originally posted by turnturtle
your rig gets wet, therefore it's heavier to handle? |
the amount I capsize that's situation normal.
Molecular weight of water vapour is approx 18 g/molsMolecular weight of dry air (average of it's components) is approx 29 g/mols
edit ....see above, Al posted same time as me, didn't see it.
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Posted By: boatshed
Date Posted: 23 Feb 15 at 3:32pm
Originally posted by alstorer
6.02x10^23 atoms/molecules/other of a substance.
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As the chemistry joke goes "I don't trust atoms, they make up everything"
------------- Steve
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Posted By: Strangler
Date Posted: 23 Feb 15 at 4:15pm
The excellent Frank Singleton website will answer your question-
http://weather.mailasail.com/Franks-Weather/Weight-Of-Wind
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Posted By: Steve411
Date Posted: 23 Feb 15 at 4:15pm
Originally posted by boatshed
Originally posted by alstorer
6.02x10^23 atoms/molecules/other of a substance.
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As the chemistry joke goes "I don't trust atoms, they make up everything"
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That's quite a good joke for a chemist.
------------- Steve B
RS300 411
https://www.facebook.com/groups/55859303803" rel="nofollow - RS300 page
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Posted By: sargesail
Date Posted: 23 Feb 15 at 7:49pm
Steve,
As per my answer on the 300 site: you were cold (and old).
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Posted By: fab100
Date Posted: 23 Feb 15 at 10:49pm
Here's a different whacky theory Mr B...
Inland, some days the breeze is quite 'clean', relatively stable in strength and direction. My guess is that most of the air flow here is horizontal. Other days, the wind feels all chopped up, just all over the place; burgees spin and tell you the opposite to the tell-tales, the boat won't settle into a stable groove. My interpretation (FWIW) is that there is a significant element of mixing of the layers, with down drafts, up drafts etc.
In the latter case, it's virtually impossible to get the rig working efficiently, perfect trim in one bit of the sail is totally wrong on another. As a consequence, you work harder and the rig fights back; harmony and equilibrium just ain't gonna happen.
I reckon this is what you faced. Further, I'd wager that if you spoke to someone trying to trim an asymmetric kite in the same race, they'd say it was noticeably even more of a bitch of a job than usual.
On these days, I've been on a run in my laser and had the lower quarter of the sail blow up and back as if the wind was blowing out of the water and up at 45degrees from in front of me. , whilst the rest was happy I was indeed on a run.
In Clive's http://clubsailor.co.uk/wp/for-fun/vocabulary-of-wind/" rel="nofollow - vocabulary of wind t his is called a "what the ****".
------------- http://clubsailor.co.uk/wp/club-sailor-from-back-to-front/" rel="nofollow - Great book for Club Sailors here
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Posted By: sargesail
Date Posted: 24 Feb 15 at 12:16am
Agreed Clive. The models/thinking tend to assume this generally horizontal, or at least consistently off horizontal flow where the reality on a cold, especially gusty day, and especially somewhere like BCYC with a steep sided dam and surrounding hills, then the breeze is moving in chunks (in MAtt's Vocab of Wind (no link I'm not a published author,'it's blowing chunks' - the allusion is deliberate). Those chunks have much more vertical movement than normal breeze.
I like to classify gusts as rollers, movers, lines and splats. A variety on splat is the bouncer which doesn't do a conventional splat fan and spread, but stops and starts on it's progress down the lake (you need a long lake and a good vantage point to see this effect).
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Posted By: alstorer
Date Posted: 24 Feb 15 at 7:08am
Originally posted by boatshed
Originally posted by alstorer
6.02x10^23 atoms/molecules/other of a substance.
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As the chemistry joke goes "I don't trust atoms, they make up everything"
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Pfft! The slightly vague description is because, eg, a mole of water contains three times as many atoms as a mole of helium. A a mole of common salt would be 6.02x10^23 sodium ions plus 6.02x10^23 chloride ions- thus "other".
------------- -_
Al
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