sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
Sail-World.com : America's Cup: Predictwind - Marginal conditions for Day 5
America's Cup: Predictwind - Marginal conditions for Day 5


'The America’s Cup Race Course, framed by the Golden Gate Bridge - today the wind blows from right to left, and the ebbing tide flows from left to right against the windflow. The blue sea that can be seen behind the City to the right, is not ocean but the greater expanse of the San Francisco Bay - which exits through the relatively narrow channel under the Bridge.'    © Richard Gladwell    Click Here to view large photo

Predictwind indicates that fresh winds winds will again prevail for Saturday, Races 8 and 9 of the 2013 America's Cup. The first race starts at 1.15pm on Saturday, local time with the second race scheduled for 1415hrs. Racing has concluded in the 18fter International.

Today we show a new feature of Predictwind - course routing optimised for wind and tide on the AC race course. See bottom of story for the course vatiations.

Officially the breeze is being forecast at 19-23kts. Today is the first race day which will be held in an ebbing (outgoing tide) which will see a wind against tide condition in the main channel of the course - building standing waves which will require a more seamanlike approach to mark rounding at Mark 1 and Mark 3 in particular. At the bottom of the course there is minimal tidal effect on the sea condition.

With the racing at its regular start time of 1315hrs the two feeds produced by Predictwind indicate that winds will be averaging around 22kts, with the breeze having been up all night at around 15kts. The key point is that on the graph image the two weather feeds produced by Predictwind are very close together for the ten hours leading into the race start suggesting the the certainty of the prognosis is high. There is only a small amount of breeze build before the start, although for Race 2, winds are predicted to be over the limit of 23 kts with the feeds showing 23-24kts.

Today there was a heavy fog over San Francisco, which lifted as the morning progressed. However the City remains overcast - which may restrict the inland heating which drives the Frisco 'Doctor'. When there is fog, the cold air on the sea gets angrily sucked in by the hotter inland systems, increasing the strength of the breeze. Unfortunately the fog is not easy to predict or measure and so it is a random factor in the forecast.

Wind map for September 14, 2013 San Francisco at 1315hrs - Start of Race 8 - wind strengths are indicated in the colour bar in the top right hand corner of the image -  PredictWind.com   Click Here to view large photo

The above image shows the wind speed and direction at 1300hrs with breezes expected to be 22kts at the start of Race 8 - these are only average speeds and gusts will be higher, but not enough to exceed the wind limit. There is a little variation in the forecast indicating a higher degree of certainty as to the outcome.

The key feature of the forecast is close agreement between the two feeds as to the rate of build of the breeze, and around race start they are consistent in their projection.

A feature of the wind image map for both 1300 and 1400hrs (above and below) is the intensity of the breeze in the actual race area - driven by the surrounding topography, which is factored into the detailed 1km forecast option used to compile these predictions. Surrounding the race area, winds are significantly lighter in strength at both times. The wind source, to the west of Golden Gate Bridge is also less strong than the strength to the east of the landmark - again a function of the wind being sucked between the two high headlands on which the Bridge is constructed, before fanning out into San Francisco Bay and losing intensity.

A similar but reverse effect happens with the tide flowing from east to west, against the wind, and with the massive body of water which forms San Francisco Bay trying to exit under the Golden Gate Bridge - a little like a bath draining down a plughole - with the plughole being the entrance to the Bay under the Golden Gate Bridge.

Wind graph for September 14, 2013 San Francisco at 1315hrs - Start of Race 8 - indicated by the vertical yellow line. Read the actual data above the graph section -  PredictWind.com   Click Here to view large photo

The second image (above) shows a graphic representation of the wind build - confirming the numbers for the prognosis. If the breeze builds later than predicted, then the light winds soon one the left of the graph will extend through to the race start time.

Wind map for September 14, 2013 San Francisco at 1415hrs - Start of Race 9 - wind strengths are indicated in the colour bar in the top right hand corner of the image -  PredictWind.com   Click Here to view large photo

The top image shows the wind speed and direction at 1400hrs with breezes expected to rise to 23-24kts at the start of Race 9 - these are only average speeds and gusts will be higher, probably exceeding the wind limit of 23kts.

The key feature of the forecast is agreement between the two feeds as to the rate of build of the breeze, and again around race start they are consistent in their projection.

Wind graph for September 14, 2013 San Francisco at 1415hrs - Start of Race 9 - indicated by the vertical yellow line. Read the actual data above the graph section -  PredictWind.com   Click Here to view large photo

The second image (above) shows a graphic representation of the wind build - confirming the numbers for the prognosis.

The third chart (below) shows the wind expectations for Saturday and Sunday. Typically the forecast for Sunday is revised upwards closer to the time of the race start. Note that sea conditions described in this chart are based on open water and are not descriptive of an enclosed harbour

Wind predictions for September 14 - 15, 2013 San Francisco -  PredictWind.com   Click Here to view large photo


The courses optimised by Predictwind for an AC72 show that the optimum course only has a small variation between the two races. The faint purple line shows the recommended course for Race 8 and the red dotted line shows the course recommended for Race 9. The mark positions used in this projection are only very approximate - and will vary on the course set for the day.

Downwind course projection September 14, 2013 - faint purple line is for Race 8, Red dotted line is for Race 9 -  PredictWind.com  


Upwind course projection September 14, 2013 - faint purple line is for Race 8, Red dotted line is for Race 9 -  PredictWind.com  


Two weather feeds are used by Predictwind, the key to the accuracy of the forecast lies with the graphs, as when the two lines for the two feeds are quite close together and following each other in the trend, then the likelihood of the forecast is high. If there is separation to any marked degree, then there still some issues to be resolved but usually 24 hours from the race they are well aligned.

The strength of the ebbing tide and standing waves can be seen in this buoy just to seaward of the Golden Gate Bridge. -  © Richard Gladwell   Click Here to view large photo

The Predictwind model takes various weather feeds and then polishes these, part of this process is factoring in the effect of local topography on the breeze - well demonstrated by the image with the funneling of the breeze.

Developed by former Olympian, Jon Bilger (470, 1992), PredictWind application was used by the Swiss team Alinghi to win the 2003 and 2007 America's Cups, and has become the leading wind system used by racing and recreational sailors around the world. It is available on a subscription basis and also with a free forecast option.

A mobile app for Android and iPhone is available and PredictWind is probably the most used app on the Sail-World iPhone.

Real time local wind observations have been added as further functionality.

You can check the weather anywhere in the world, and get a five day forecast, plus a variety of other features and functions of PredictWind. The app is synchronised with your PC, so that your latest set of locations are always available without resetting each time you change a device.


by Richard Gladwell


  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=114477

2:23 PM Sat 14 Sep 2013GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.

Click for further information on
2013 America's Cup

Related News Stories:

19 Jan 2014  America's Cup: CNN Mainsail Down Under on the state of the Cup
16 Jan 2014  America's Cup: Jobson goes one on one with Jimmy Spithill (Part 5)
15 Jan 2014  America's Cup: Jobson goes one on one with Jimmy Spithill (Part 4)
14 Jan 2014  America's Cup: Jobson goes one on one with Jimmy Spithill (Part 3)
12 Jan 2014  America's Cup: Jobson One on One with Spithill (Part 2)
11 Jan 2014  America's Cup:Gary Jobson goes One on One with Jimmy Spithill
06 Jan 2014  America's Cup: Rod Davis - still looking for answers after Cup defeat
01 Jan 2014  America's Cup: Russell Coutts on the 34th and 35th America's Cups
28 Dec 2013  Rolex Sydney Hobart: Southerly change expected to hit at midnight
03 Dec 2013  ISAF Sailing World Cup Melbourne: Lighter breezes for Day 2
MORE STORIES ...




News - USA and the World

Volvo Ocean Race: Chris Nicholson Interview - Part 3 - On the Atoll *Feature by Richard Gladwell/Sail-World.com/nz
Final part of a three part, 80 minute, interview with Team Vestas Wind skipper, Chris Nicholson on the wrecking of the Volvo Ocean Race yacht on an idyllic atoll in the South Indian Ocean during the night of November 29. In this part, Nicholson tell what happened once the crew stepped aboard the local coastguard boat just after dawn, and subsequent trips back to the wreck. ... [more]  

A successful medal haul for the Australian Sailing Team (AST) at the ISAF Sailing World Cup in Melbourne with five gold, five silver and three bronze in the Olympic class program, plus two gold and one bronze in the Paralympic fleet. Hear what the sailors had to say about their performance, along with some great video footage of the week's racing on Port Phillip. ... [more]  

Bart’s Bash, the global sailing race that took place in 60 countries around the world, on September 21st, 2014 raised an incredible £366,391.95 for the Andrew Simpson Sailing Foundation. The race was held in memory of Andrew 'Bart' Simpson, the Olympic gold medal sailor who died in May 2013. ... [more]  

RORC Transatlantic: As with every yacht participating in the race, staff from Camper & Nicholsons Port Louis Marina greeted the French team on arrival with warm congratulations, a cold beer and a welcome basket from the Grenadian Tourism Association on behalf of the people of Grenada. The crew of five looked tired after nearly 17 days at sea, but owner, Frank Lang was full of praise for his crew. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - Perpetual Loyal is no stranger to the Rolex Sydney Hobart. Winning line honours in 2011, they have continued to be a contender, especially in heavier breezes. ... [more]  

In a lot of ways, it was kind of befitting that the best conditions of the last day of the Sailing World Cup – Melbourne, were saved for the Women’s Laser Radial Medal Race. Apart from highlighting them in glorious sunshine, like Huey’s own spotlights, it also brought into frame that were only two girls 470 crews in attendance for the regatta. ... [more]  

The website for the 2015 Finn Gold Cup in Takapuna, New Zealand, has been launched. The Finn class is eagerly anticipating a return to Takapuna Boating Club for what will be only the second Finn World Championship to be held in New Zealand. It will have been 35 years since Cam Lewis (USA) beat John Bertrand (USA) in a thrilling final race showdown in 1980, to take the Gold Cup. ... [more]  

Looking for a great Christmas present which you can buy with a few mouse clicks? Bob Fisher's books on the Round the World races, Farr 40's and the definitive America's Cup two volume set are still available, along with other titles from South Atlantic Publishing. ... [more]  

Clipper Round the World Yacht Race - In January Nqoba, from Durban, will embark on his Yachtmaster qualification and will have none other than legendary sailor Sir Robin Knox-Johnston, the first man to ever sail solo, non-stop round the world in 1968-69, as his mentor as he takes the first steps to realise his dream of circumnavigating the globe at the helm of a Clipper 70. ... [more]  

IFDS 2014 Worlds: But as you reflect back on the year, we hope you will agree that week of competition in Halifax, Nova Scotia set a new standard for disabled sailing. It was the largest world regatta yet with 18 SKUD-18 teams, 14 Sonar teams and 49 2.4mR competitors and the largest number of countries participating. There were some challenging days finding enough wind to race. ... [more]  

The 2015 McDougall + McConaghy Moth World Championship is set to be even more of a spectacle this year, with the return of the Zhik ‘Mothapolooza’ which promises a potential head-to-head with teams of America’s Cup and Olympic sailors. ... [more]  

Volvo Ocean Race: Chris Nicholson Interview - Part 2 - On the Rocks *Feature by Richard Gladwell/Sail-World.com/nz, Auckland, NZ
Part 2 of three part, 80 minute, interview with Team Vestas Wind skipper, Chris Nicholson on the wrecking of the Volvo Ocean Race yacht on an idyllic atoll in the South Indian Ocean during the night of November 29. In this part, Nicholson covers what happened from the time the Volvo65 hit the reef on the SE corner of the Cargados Carajos Shoals. ... [more]  

Last Saturday saw the third annual St. Maarten Regatta Beach Clean-Up organized by the St. Maarten Regatta as part of the Regatta Art Competition. Unfortunately, due to exams, not many children showed up. ... [more]  

US Sailing’s Olympic Sailing Committee (OSC) has released the selection procedures for the 2016 U.S. Olympic Team (Sailing) in the 10 events selected for the Rio de Janeiro 2016 Olympic Games. The Games of the XXXI Olympiad will take place from August 5-21, 2016, and the sailing events will be based at Marina de Gloria on Rio de Janeiro’s harbor front. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - When the cannon fires sending the 118 entries on their way in the Cruising Yacht Club of Australia’s 70th Sydney Hobart Yacht Race on December 26, two yachts will stand out, because they first competed back in the early days of the race. ... [more]  

Volvo Ocean Race have announced from their headquarters in Alicante, Spain that an independent report has been commissioned into the grounding of Team Vestas Wind’s boat on a reef in the Indian Ocean. The report will be released during the Auckland stopover. ... [more]  

The French sailor scratches his newly shaved skin. He tentatively reaches towards a plate of fried chicken pieces. Still not sure. He rubs his chin again. He hesitates. Laurent briefly runs his eye over the other plates, but finally he can no longer resist the crispy fried chicken pieces. 'This is what I’ve been waiting for,' says the cheerful Frenchman. ... [more]  

Transatlantic Race: After time correction, Apollo 7 is leading IRC Two. Nigel's team included three close friends from his home town of Plymouth, Devon: Steve Wassell, James Slater and Mark Davies. Also on board were two offshore specialists: Dan Gohl, a past Class40 world champion and Sevenstar Round Britain and Ireland Record holder as well as Rolex Fastnet Race winner Brett Aarons. ... [more]  

The 2014 OK Dinghy World Championship opens at Black Rock Yacht Club on Port Phillip Bay in Melbourne, Australia, on December 28th and so far there are around 80 entries, with perhaps a few more before registration closes. This 52nd OK Dinghy World Championship will be the third time that Black Rock YC has hosted the event, following 1982 and 1990. ... [more]  

Adelaide Sailing Club played host once again to the Melges 24 class for its 'Christmas Sprint Series', the third three day M24 regatta in five weeks held by ASC which, (in the same season the club is also hosting the M24 Australian Championship) says something about the power of persuasion, energy and organisation being put in to M24 class by its Australian Secretary Donna Evans. ... [more]  

The team, led by Jerome Clerc, will not compete on the 2015 Extreme circuit but intends instead to focus entirely on the Decision 35 Vulcain Trophy season in Switzerland. The professional sailing squad onboard Realteam capped a superb 2014 season with a third place in Sydney last weekend that put them on the third step of the overall Extreme Sailing Series Championship podium. ... [more]  

Volvo Ocean Race: Chris Nicholson on the Team Vestas Wind disaster - 1 *Feature by Richard Gladwell, Sail-World.com/nz, Auckland, NZ
Part 1 of three part interview with Team Vestas Wind skipper, Chris Nicholson on the wrecking of the Volvo Ocean Race yacht on an idyllic atoll in the South Indian Ocean during the night of November 29. In this part, Nicholson discusses the factors leading up to hitting the reef, interspersed with other research information, charts, video and images. Parts 2 and 3 will follow on consecutive days. ... [more]  

USA 4 Windsurfing campaign by USA 4 Windsurfing Campaign
Change is inevitable. No matter how hard you try to keep things the same, there comes a time when you must move on. The harder you resist, the more difficult the change. ... [more]  

2014 Rolex Sydney Hobart Yacht Race - Bob Oatley’s Rolex Sydney Hobart race record holder, Wild Oats XI, is out of the water for a final modification after a high speed and rough weather training run off Sydney. ... [more]  

This is Peter Perfect in the Turbo Terrific from the 60s cartoon series, the Wacky Races. Of course, to Australians and a plethora of motoring enthusiasts the world over, the real life Peter Perfect will always be The King of The Mountain. RIP Brocky (Peter Geoffrey Brock). ... [more]  

RORC Transatlantic Race 2014: The Spirit of Adventure crew of 15 were met dockside by representatives of the Royal Ocean Racing Club and well wishers at Camper & Nicholsons Port Louis Marina. After enjoying an ice cold beer, the first cold drink for two weeks, the crew cleared customs and headed for the Victory Bar for eggs and bacon. ... [more]  

ISAF World Sailing Rankings - 15 December 2014 - The World Cup Final was a 100-point regatta and whilst Shaw took maximum points, Tartaglini’s eighth was enough for her to hold on to World number one heading into 2015. Shaw remains at World number two with Laura Linares (ITA) at World number three and 2014 World Champion Charline Picon (FRA) at World number four. ... [more]  

Comanche; Supermaxi Showdown VIDEO by Dale Lorimer, Sydney
In what is touted to be one of the most hotly contested Rolex Sydney Hobart line honours battles in recent history, there's been plenty of on-water supermaxi activity over the last week. ... [more]  

Commodores Cup - There was barely four knots of wind for the start of race one today. Brian and I started in port tack, at the committee boat, hit the right corner, and never looked back. There were a few tricky moments on the first run, in four knots of wind, but we managed our position well. For the second lap, the breeze built to six knots and steadied out a bit which made out lives easier. ... [more]  

2014 /2015 International Audi Melges 20 Miami Winter Series - Event No. 1 - One final light air race concluded the 2014/15 Audi Melges 20 Miami Winter Series Act No. 1 on Sunday, hosted by Coconut Grove Sailing Club (CGSC) with championship winner Jason Michas on Midnight Blue along with tactician Mark Mendelblatt and crew Trevor Moore winning the final heat and taking the overall win. ... [more]  

2014 RORC Transatlantic Race - Aref Lahham's Swan 68, Yacana crossed the finish line of the RORC Transatlantic Race on Sunday 14th December at 03:25 UTC. The crew are all friends from Greece and the German Frers designed yacht with classic lines is beautifully maintained and balanced for a heavy displacement yacht. ... [more]  

2014 Extreme Sailing Series - Act 8 - The Wave, Muscat’s long tenure of the Extreme Sailing Series crown came to an end in Sydney today when Swiss team Alinghi won the eighth and final Act of the year to take an overall victory in the 2014 series despite a superb late challenge from Tom Slingsby on Oman Air. ... [more]  

Images of the Extreme Sailing Series, Act 8, Sydney, Australia and video about most memorable in the Series' eight-year history. The Series was won by Alinghi after an action packed three days of racing on the confines of Sydney Harbour, which was the venue for the international series for the first time. ... [more]  

Volvo Ocean Race: Dongfeng Race Team - Leg Two review
Extreme Sailing Series: Alinghi crowned 2014 and Sydney champions
Extreme Sailing Series -Sydney Land Rover recognises talent
ISAF Sailing World Cup Melbourne - Medal Race Images
Extreme Sailing Series: Alinghi dons ESS Crown, Oman Air wins award
18ft Skiffs: Rooklyn scores win in Syd. Barnett Jr. Memorial Trophy
ISAF Sailing World Cup: Fan cranks up for final Melbourne day + Videos
Miami Star Winter Series - Commodores Cup Day 1
Extreme Sailing Series: Delayed coverage - Day 4 +Audio *Feature
Volvo Ocean Race - Dongfeng score another excellent result
Audi Melges 20 Miami Winter Series - Fleet rumbles in Miami
Extreme Sailing Series - The Wave, Muscat see championship bid slip
2014 RORC Transatlantic Race - From acorns grow oaks
Volvo Ocean Race - Team Brunel (NED) wins Leg 2
2014 RORC Transatlantic Race - Oakcliff Ocean Racing Team wins
Extreme Sailing Series: Day 3 image gallery from Sydney Harbour *Feature
The Extreme Sailing Series™ - Action-packed day on Sydney Harbour
Early Christmas presents for ISAF Sailing World Cup medallists + Video
Volvo Ocean Race: Leg 2 finish - Team Brunel wins from Dongfeng *Feature
Audi Melges 20 Miami Winter Series - Day 1 overall
2014/2015 Audi Melges 20 Miami Winter Series - Images by Joy Dunigan   
Extreme Sailing Series: Live coverage - Day 3 +Audio *Feature   
St. Maarten Heineken Regatta kicks off with successful sponsor party   
Successful seventh edition of 2014 World Yacht Racing Forum   
2014 Star Sailors League Finals - Catching up with Robert Stanjek   
2014 ISAF Sailing World Cup - Melbourne - Day 6 Preview   
Extreme Sailing Series - Act 8 Photos and season highs and lows video   
Volvo Ocean Race 2014-15 Leg Two - Final fight to the finish + Video   
Extreme Sailing Series Act 8 - McMillan tops table in Sydney + Video   
Anna Tunnicliffe: Alinghi - Day 2: Extreme Sailing Series, Sydney   
ISAF SWC Melbourne - Top ten prepare for Port Phillip showdown + Video   
Extreme Sailing Series Act Eight 2014 – Photos by Andrea Francolini   
Volvo Ocean Race: Three way alley-brawl on final day of Leg 2 *Feature   
International Audi Melges 20 Miami Winter Series 2014-15: Holiday heat   
ISAF SWC Melbourne: Family affair for Papua New Guinea sailors + Video   
Australian 18 Footers League Club Championship - Stormy capsize   
RORC Transatlantic Race - Lupa spice it up for Line Honours victory   
Extreme Sailing Series: Replay coverage - Day 2 +Audio *Feature   
America's Cup: Oracle crew member's penalty for cheating is reduced *Feature   
US Tour: Four GC32s to compete at Quantum Key West Race Week + Video   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News





Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
XLXL NEW US
LocalAds   DE  ES  FR  IT