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How much wind is this?


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PSCRaces-316.jpg

PSCRaces-323.jpg

More pics here https://www.amorisenyfineart.com/Sailing/PSC-Races-August-15-and-16-2020/n-4HWZxt/i-W9ZRFsL

A fabulous day of racing with the wind from the perfect direction, the South.The reason for that is the wind has the large expanse of water to build up good waves, I would guess today they are about 2 feet high today.It was tons of fun surfing them downwind. 

Anyway, can anybody guess how much wind that is in the pics?

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Is there a prize? Just kidding. Looking at the beginnings of small whitecaps and the lack of serious hiking, my GUESS is 10 - 12 kts. Please post the answer soon so I can stop wondering.

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19 minutes ago, xonk1 said:

Is there a prize? Just kidding. Looking at the beginnings of small whitecaps and the lack of serious hiking, my GUESS is 10 - 12 kts. Please post the answer soon so I can stop wondering.

12.1 kts.....  :P

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12 minutes ago, Eddie_E said:

14~16 good white caps start

18~20 the tops blow off the white caps.

When my lake (and my Force 5) look like the pic, my wind app and my weather app say 8-10mph. Boat speed then is 7-8kts on fastest points of sail.

I've always been curious about what it would be if I actually measured it (...but not curious enough to go buy an anemometer...).

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On salt water, at about 15 kt spindrift... long straight lines of foam aligned with the wind... begins to form, by 18kt it's quite noticeable. I think it's a bit higher than than for fresh water.

Boats not heeling or making a lot of dramatic reaction, looks like 10~12 to me.

FB- Doug

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Only 12 knots! Wow! I really thought it would be more than that! I suppose I know now what that wind speed feels like.

If this helps, I am 125 lbs, I was sailing the Sunfish and in the strongest gusts I had to let the front of the sail luff to keep the boat flat.

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Pictures are rarely a good represention of reality when it comes to wind or its affect on the waves. They do not capture the movement of the waves and the sparkle of spray vanishes. 

But the boats tell more. None of the crew are hiking fully, none of the sails are feathered or flapping, not even at the top. They are coping quite well without a big effort. So my assessment is its no more than about 12kts.

Its a long fetch from that bridge in pic 1 so plenty of room for waves to build. If it was windier than 12 the waves would be much bigger and better defined.

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 Tillerfort Wind Scale

  1. Crouch in the cockpit
  2. Sit on the side deck
  3. Butt over the side.
  4. Straight leg hiking
  5. Tighten all the controls and hike as hard as I can
  6. OMG I think I'm going to lose it
  7. Lost it

 

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Fresh water will start white capping around 12 knots of breeze.  Frequent white caps you're seeing 15ish.  White caps everywhere, like water boiling 20+.  The longer the fetch the breeze has across the water the better the swells will be.  I've heard the theories regarding altitude and breeze having more or less punch due to air density differences in altitudes.  Not sure I believe those....

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25 minutes ago, RobbieB said:

Fresh water will start white capping around 12 knots of breeze.  Frequent white caps you're seeing 15ish.  White caps everywhere, like water boiling 20+.  The longer the fetch the breeze has across the water the better the swells will be.  I've heard the theories regarding altitude and breeze having more or less punch due to air density differences in altitudes.  Not sure I believe those....

Altitude definitely affects the power of the breeze, some of the big dams around Johannesburg are above 3000ft above sea level, at always looks like there is 5 to 8 knots more breeze than it actually feels like when you are sailing, so big chop in relatively light  feeling breeze, whereas at the coast similar looking conditions mean plenty of hiking and dowering.

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23 minutes ago, Major Tom said:
53 minutes ago, RobbieB said:

Fresh water will start white capping around 12 knots of breeze.  Frequent white caps you're seeing 15ish.  White caps everywhere, like water boiling 20+.  The longer the fetch the breeze has across the water the better the swells will be.  I've heard the theories regarding altitude and breeze having more or less punch due to air density differences in altitudes.  Not sure I believe those....

Altitude definitely affects the power of the breeze, some of the big dams around Johannesburg are above 3000ft above sea level, at always looks like there is 5 to 8 knots more breeze than it actually feels like when you are sailing, so big chop in relatively light  feeling breeze, whereas at the coast similar looking conditions mean plenty of hiking and dowering.

Air temperature certainly makes a difference, why wouldn't density due to altitude? Not sure what the multiplier would be, but for sure, a cold gusty day has a lot more punch in the wind's force, than the same velocity wind on a warm day.

FB- Doug

 

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