What do you know about wind?

[Wild Wassa]

Once upon a time, far far away, or insert long long ago, when the night was dark and stormy but still, I asked a question about wind and Barb B. said, "They are called cat's paws."

That's when I realized that I knew absolutely nothing about wind. Absolutely nothing.

I've been studying wind, since then. I think wind and pressure variations are most interesting.

Please tell me what you have found about wind and how your prevailing winds make you the sailor that you are.

Where I sail the prevailing wind looks like this ... I call them darkies when they are on the water and visible, they are ghosts when they're above the water. Photo of Lake Barely Sailable's Central Basin and the Racecourse.


http://i225.photobucket.com/albums/dd301/WildWassa/LakebarelySailable.png


I've studied winds on lakes that I race on, and I/we have lost the plot at sea where winds are kid's play. I can pick lifts and knock and the phases and frequencies, they're no drama, but I still just don't get it like Super Sailors do. It isn't about sail trim or tuning or boat prep, we have that sussed right out, ... it is about wind and pressure that I'm looking for. Something is missing.

Please tell me what you know about wind ... one hint that's all, that's all I'm looking for to take the game to a different level.

Warren.

[paladin]

It's cheap until you try to catch it......

[Tom Hunter]

I don't know much, but here it is for what it's worth.

Locally the wind changes based on where the sun is in relation to the clouds. For example it will move from one side of a race course to another. I have not gotten very good at predicting it, but sometimes I score. A couple of years ago we were in last place in the NOODs, third race of the day and I had the pattern down. Sent the skipper off to where the wind was going to be in 10 minutes and we caught half the fleet that way. If only we had been in the middle instead of last!

I can't make that kind of call with any consistency, but it shows how much ground you can gain when you know where the wind will be and no one else does.

My sloop's mast is very faw forward and she has a lot of weather helm. She also has a full keel and responds slowly. If I am in good form I can counter steer before the puff and get the forces of the rudder and the main in balance when the puff hits. That gets us some speed without rounding half way up and then coming back down. Which makes the point it is not just the wind, it's the wind and the boat.

Interesting topic, I hope others with more experience will chime in.

[Noah]

Wassa,

It seems a point you are making is it's all about understanding the local conditions and forces.

My theory on sailing is that it's all about the eliminating the number of variables that you need to think about at any given moment. The more you learn your boat, etc the fewer variables you actively need to think about.

The same goes for weather - I would imagine that over time you have instinctively learned how to make quick deductions about what is happening - IE you instinctively know what forces are happening.

Now you are going to a new place with a "sea breeze" and suddenly there are lots of variables, and you don't have enough knowledge to know what they all mean. I'm sure real waves, tides, etc have huge effects that the local sailors have instinctively figured out.

For us on Lake Champlain there are either fronts which produce winds with gusts, etc that need to be understood, or there are convection winds. The two types of winds both have very different sets of influences. As Tom mentioned, we often start by looking up - clouds have a huge effect here, as does the sun on land masses. When it's light it's all about the convection between land and water.

[Jay Greer]

I do know that, when sailing a schooner, the wind is always on the nose;
no matter what direction you are traveling!
Jay

[johngsandusky]

Study and practice bring intuition.

[gavinpascoe]

this is what I've heard, and open to variables of course, but generally,

Northern Hemisphere: Starboard tack is favoured
Southern Hemisphere: Port tack is favoured

I understand wind veers more often than it backs. Is this true?

Another tip - if you're not helming - watch its angle and the expression of the face of the person holding it: You can create a whole scientific scale based on the redness of face or blueness of language!

[boylesboats]

what do I know about winds?

They blows, right?

[gavinpascoe]

Yes - sometimes it blows 7 bastards, sometimes 40. 7 was used to describe Wellington, and 40 in Auckland. It's either a backward sliding scale, or Aucklanders are prone to talking themselves up. I suspect the latter ;-)

[Chip-skiff]

I studied wind while I was fighting wildland fires— when there are flames involved, it stimulates your awareness.

In any event, I think of wind at three scales: regional (e.g. trades, or prevailing westerlies); temperature or pressure gradient (high/low, offshore/onshore or updraft/downdraft); and local terrain (turbulent swirls off rocky headlands, dead spots under cliffs, up- or down-drafts at the mouth of stream or river inlets).

Generally, the regional flow establishes the pattern and the other two modify it. Every place has different combinations of this, and while sailing one develops a mental map.

One characteristic pattern here (US central Rockies) is the intense vertical circulation crowned by billowing clouds (thunderhead).

Typically, as a thunderhead passes, there is first a strong gust-front (7+ bastards) in the direction it's travelling, followed by lesser gusts that compass in a clockwise direction as the cell passes. (I think clockwise, anyhow.)

When I sailed in New Zealand, the offshore-onshore patterns were the focus, with temperature-circulation cells (squalls) a complicating factor. (Plenty of bastards in Lyttelton Harbour, but I was too busy to count.)

Once you get the basic physical stuff, the local patterns are a lot more comprehensible. And they tend to repeat themselves.

Of course the fine-tuning is to watch the water surface for shifts and puffs. No substitute for that. And feeling the boat respond to the changes in the wind is an immediate feedback.

Endlessly fascinating—

Chip

[Wild Wassa]

Thankyou Skippers.

I might add a few things that I have found and do.

There is an excellent book called 'Wind Strategy' by Paul Houghton and Fiona Campbell, published by Wiley Nautical. This appears to be the state of the art thinking ... if such a thing is possible.

PredictWind.com was founded by John Bilger and setup for the Americas Cup held in NewZild. John Bilger was in charge of the weather team, during Alinghi's campaigns. PredictWind is the only marine wind forecast website using a 1km weather resolution model, which gives 1km centres for wind arrows. This is a higher resolution than similar sites afford.

Here in Oz the BOM, provides historic wind data which is proving most valuable. The data which I'm particularly interested in is for, Port Phillip Bay and Port Melbourne. The data available is recorded at Melbourne Airport and Point Beacon, both sets of data collate (well).

One of the reason that I asked the question is that, where the Royal Victorian Yacht Club who are hosting the coming Nationals and World Championships for the International Flying Fifteen, to date they have not ever held a race for a Flying Fifteen where the course will be for the Championships, which I find to be extraordinary. So no one I've talked to knows much at all about what to really expect from the boat in the middle of the Bay. For those who know Port Phillip Bay, the course will be a 1/3rd of the way between Gellibrand Shoals and Point Cook Reef.

We have sailed in the exact area twice now, for a passage race between Melbourne and Geelong and a cruisy look around to get a feel, but not in the Fifteen. The wind pattern was extremely difficult for me to understand on Port Phillip Bay, in that area and in the short time I spent there.

Guys who race will know, that after the start if you can hold your lane for the first 2 minutes, you will be in the top 1/3rd of the fleet while other are getting spat out the back but if you can pick the first shift, you will immediately be in the top 10% of the fleet. It is so important because the fleet will be very big. These coming races will not be like our normal 50-70 boat races, the fleet will be big.

I though that there may have been rules of thumb that I had not learnt.

I pretty well understand how things work about thermal mixing and how cold air and warm air moves to the left and right and which way the wind is rotated coming off land or differently over water well away from land, and which way fast and slow moving air rotates, and that the gusts on Port Phillip bay predominantly move left.

Getting wind right appears to be all about making sure your attention span, is at the right span, at the right time and the tic-tac is on the boat. After the 20 or so races that we will do in Melbourne, I'm sure we will get the conditions sorted by then. I just want them sorted well before we go there.

Please keep all thought coming ... I'm taking it all in.

Warren.

[Wild Wassa]

Chip Skiff, it was on the fireground that gave me a real appreciation for wind and survival. During the really bad fires or when ever possible, we all took turns doing it, there were teams dedicated to calling the weather, who were standing off the fire, up high somewhere or even within line of site, calling the gusts and shifts and air temperatures and doing all that stuff. Swinging things.

I felt a hell of a lot safer when I knew a weather team was on the fire ground. There are no weather patterns like those created by big fires, as you well know. The temperatures of some of the gusts ... just adds fuel to fire.

Warren.