sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
Sail-World.com : America's Cup: Predictwind - Wind direction impacts Day 11 + Five days
America's Cup: Predictwind - Wind direction impacts Day 11 + Five days


'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

A breeze that is from a more southerly direction is expected to delay or even preclude racing on Day 11 of the 34th America's Cup, for Saturday and Races 14 and 15 of the 2013 America's Cup. The first race was due to start at 1.15pm on Saturday, local time with the second race scheduled for 1415hrs.

Towards the bottom of this story we feature Predictwind's course routing optimised for wind and tide on the AC race course, and using an AC72 performance profile. It is included to show that the effect of the tide on the race course and race strategies. See bottom of story for the course variations.

For the official line on how the current factor is determined click here

Wind graph for five days from September 21, 2013 San Francisco at 1315hrs - Sunday’s race is indicated by the yellow line. Read the actual data above the graph section. Shows that there are two days under the wind limit, before the wind exceeds the wind limit on the two following days. -  PredictWind.com   Click Here to view large photo


Officially the breeze is being forecast as being from a southerly direction, if this remains the case at race time, it will not be possible to set a course until the wind swings into the West, blowing straight down San Francisco Bay. When the wind does swing it is expected to be in the 16-19kts range. It has also been raining heavily in San Francisco.

With the racing at its regular start time of 1315hrs the wind feeds produced by Predictwind indicate that winds will be around 16-18kts. The key point is the direction of the breeze, which one feed shows as being from the West and the other from the SW, we have regarded the latter feed as being the more accurate of the two when there is a variation between the two independent feeds.

Wind map for September 21, 2013 San Francisco at 1315hrs - Start of Race 14. The left panel shows the wind blowing across the course -  PredictWind.com   Click Here to view large photo

The above image shows the wind speed and direction 1300hrs with breezes expected to be 16-18kts at the start of Race 14 - these are only average speeds and gusts will be higher, and may exceed the wind limit.

Wind graph for September 21, 2013 San Francisco at 1315hrs - Start of Race 14 - 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 significant feature is the variation between the two feeds - making for a less certain prognosis.

Wind map for September 21, 2013 San Francisco at 1415hrs - Start of Race 15. the left panel shows the wind still blowing across the course. -  PredictWind.com   Click Here to view large photo

The top image shows the wind speed and direction at 1400hrs still with the most accurate feed showing a SW wind direction making it impossible to set a course to windward breezes are also lighter in this feed, although with increased winds on the Alcatraz end of the course. On the right hand feed (PWC) the winds shown as being stronger and from the West. The feed used to develop the wind map on the left (PWG) does not show the wind swinging West until 4.00pm - over an hour after racing is permitted to start.

Wind graph for September 21, 2013 San Francisco at 1415hrs - Start of Race 15 - 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 uncertain prognosis. Reading the top line we can see the wind direction, the wind strength with winds forecast to be 15-19kts and from the SW and South.

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

Windpredictions for September 21, 2013 San Francisco for Friday and Saturday -  PredictWind.com  

The courses optimised by Predictwind for an AC72 show that the optimum course only has no real variation between races. The faint purple line shows the recommended course for Race 13 and the red dotted line shows the course recommended for Race 14. The mark positions used in this projection are only very approximate - and will vary on the course set for the day. At the bottom of the upwind leg the model shows that the boats can use the full width of the course due to the evenness of the tide.

The point here is that downwind is there is little variation in the options. And upwind in both models the fastest course is to the south, or cityside shore, aside from allowing a short leg to Alcatraz in the first race before heading for shore. The tide is expected to be in flood (incoming) for this race, and boats will need to avoid its effects upwind by taking the city shore.

Downwind course projection September 21, 2013 - faint purple line is for Race 14, Red dotted line is for Race 15 -  PredictWind.com  

Upwind course projection September 21 2013 - faint purple line is for Race 14, Red dotted line is for Race 15 -  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 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 images 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=114796

11:01 PM Sat 21 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:

23 Sep 2013  America's Cup: Predictwind - Winds expected to co-operate on Day 12
22 Sep 2013  Americas cup final photos by Carlo Borlenghi
22 Sep 2013  34th America’s Cup - Strong wind persists
22 Sep 2013  34th America’s Cup - Race 14 postponed to Sunday
22 Sep 2013  America's Cup: Monsta's view of the key moments of the 34th Match
22 Sep 2013  America's Cup: Emirates Team NZ Fans must wait another day for Race 14
22 Sep 2013  America's Cup: Race 14 postponed to Sunday - wind in wrong direction
22 Sep 2013  America's Cup: Calling the Oracle - Bangin' the Corners - Video
22 Sep 2013  America's Cup 2013 -Day 11 -Blown Out
22 Sep 2013  America's Cup - Day 11 shore side images from San Francisco
MORE STORIES ...




News - USA and the World

The expansion of sailing into so-called developing countries, continues at the ISAF Sailing World Cup, Miami, with Cuba joining the 64 nation line-up encompassing 600 boats. The 2015 fleet on Biscayne Bay is a record turnout, for this second event on the Sailing World Cup Circuit ... [more]  

At exactly 00:01 on the 29th January 2015, TeamVestas?' VO65 left VTE - Voltri Terminal Europa en route to Persico Marine in the foothills of the Italian Alps. The boat is now safely secured in a purpose-built facility near Bergamo, awaiting full assessment and the beginning of the repair process. ... [more]  

ISAF Sailing World Cup Miami Day 3 - There's a world of difference between skiing a long, smooth run and skiing on moguls. Today, forget the waves, it was the breeze on Biscayne Bay that was 'moguls.' Shift upon shift upon shift upon shift. ... [more]  

Ioannis Mitakis (GRE), the 2012 Finn European Champion, ruled the roost in Miami today with two emphatic race wins and moves up to third overall. Giles Scott (GBR) sailed his worst day so far, but still leads with a five point gap on Jake Lilley, and 12 points over Mitakis as the event reaches its half way stage. ... [more]  

The International DN Ice Yacht World and North American Championships are being held in Kingston, Ontario (right in front of our office). For the Kingston Yacht Club, we skated out to the middle of the lake, and put together a little highlight piece for them to remember the event by. ... [more]  

Doyle Sails had more success last weekend in the Auckland Optimist Championships, taking first and second overall in the 110 strong Open fleet. Six countries were represented in the event, and young sailors came the length of New Zealand to compete in the regatta that is a ranking event for World and International team selection. ... [more]  

EFG's Star Winter Series rules in Biscayne Bay by Connie Bischoff, Miami, FL
The third Star Winter Series presented by EFG (SWS) and hosted by Miami’s Biscayne Bay was a shining success. Not only have all five regattas had stronger participation than last year but the final one, the Mid Winters, grew 35% with 45% of the sailors international (CAN, SWE, BRA, UKR, ARG, ITA and GER). ... [more]  

2015 ISAF Sailing World Cup Miami - Day 3 photos provided by Ocean Images. ... [more]  

Day 3 of ISAF Sailing World Cup Miami, Presented by Sunbrella marked the midpoint of North America’s biggest Olympic and Paralympic classes regatta. With bright sunshine and fresh breeze in abundance, the world’s top athletes in 13 classes were treated to the conditions that exemplify why Miami is a preferred international sailing destination. ... [more]  

It was windshift upon windshift upon shift upon windshift on Day 3 of the ISAF World Sailing Cup Miami sailed on Biscayne Bay Presented by Sunbrella, the premier regatta has attracted 599 boats and 768 sailors who were adjusting all day to one thing or another. If it wasn't the wind direction that was changing, it was the wind speed. ... [more]  

Following the success of the Mount Gay Round Barbados Race Series that concluded last week, the dates of next year’s event have been confirmed for 16-24 January 2016. With overseas competitors from 11 nations represented a large part of the 47-strong fleet overall at the 2015 event ... [more]  

Ben Ainslie Racing, the British Challenger for the 35th America's Cup, have shipped two foiling Nacra 20 catamarans to Bermuda and have become the first team to commence sailing operations at the Venue for the next Cup. The team conducted an initial training camp in Bermuda, last week. ... [more]  

North U kicked off its 2015 season of youth match racing clinics around the U.S. with a successful clinic hosted by the Texas Corinthian Yacht Club in Kemah, Texas on Galveston Bay near Houston. Forty high school and college sailors spent two-and-a-half days learning about match racing and training in Sonars on flat water and 6-12 knots of breeze. ... [more]  

A fantastic week of sunshine, warm weather, big breeze and competitive sailing is what sailors were treated to last week in Key West. Several Canadians left the bitter cold of the north to partake in the fun filled week and a few even brought home trophies. Here's a peek at the fun in the sun! ... [more]  

At ISAF Sailing World Cup Miami, presented by Sunbrella, if the Chamber of Commerce had stayed up all night working at it, they could not have served up a better day for racing. ... [more]  

On day 2 of ISAF Sailing World Cup Miami, Presented by Sunbrella, the rainstorms of yesterday vanished but the excellent wind conditions remained in place on Biscayne Bay. A more conventional day of racing saw US Sailing Team Sperry athletes finish the day in the top 10 in 5 Olympic classes and 2 Paralympic classes. ... [more]  

Bringing Dragon Sailors from around the world to Antigua. Harmony Hall Yacht Club, with the support of the Antigua Yacht Club Marina and the Inn at English Harbour, will host the second Annual Antigua Dragon Yacht Club Challenge with nine races scheduled to take place over five days in fantastic Caribbean conditions on identical Petticrow Dragons. ... [more]  

There are so many ways that the Dongfeng Race Team could have lost the chance to win the light-air marathon from Abu Dhabi to Sanya in China. Leading from the first 24 hours to the finish, 23 and a half days later, 5,403 nautical miles sailed and eight different gulfs, oceans and seas, is not necessarily the most advisable way to try and take the spoils. ... [more]  

Sydney photographer, Michael Chittenden was on Sydney harbour last Sunday and captured these images from Race 4 of the NSW 18ft Skiff Championships ... [more]  

New Zealand short-handed sailor, Conrad Colman is on his second two handed round the world race, this time aboard the Spirit of Hungary with Nandor Fa sailing in the Barcelona Round the World Race: I had noticed a couple of chafing zones on the mainsail so I prepared some patches and the Dr. Sails flexible epoxy glue so we could drop the main quickly ... [more]  

2015 ISAF Sailing World Cup Miami- Photos provided by Ocean Images. ... [more]  

Photographer Ingrid Abery was on the water at 2015 ISAF Sailing World Cup Miami and provided this gallery of images. ... [more]  

2015 ISAF Sailing World Cup Miami - It may have been a day late for Australia Day, but on the second day at the Sailing World Cup Miami, the Australian Finn sailors were on a charge with some sparkling performances. Giles Scott (GBR) still leads after winning the opening race of the day, while Jake Lilley (AUS) won the second and moved up to second overall. Ed Wright (GBR) is in third. ... [more]  

2015 Pineapple Cup – Montego Bay Race is set to begin Friday, February 6. The 32nd edition of the venerable Pineapple Cup – Montego Bay Race will start in Port Everglades, Florida, and send its 12-boat fleet on a challenging 811 nautical mile course to Montego Bay, Jamaica. George Sakellaris’s (Framingham, Mass.) 72-foot Shockwave will be the largest boat competing, so it should be interesting to ... [more]  

VX One momentum is growing with ever larger fleets showing the pure fun and easy performance of this true thoroughbred one design. ... [more]  

Last Friday, former Oracle Team USA team member, Matthew Mitchell issued a media release stating that he has lodged a complaint with the International Sailing Federation over the actions of a fellow crew member, Simeon Tienpont, and inaction by the International Jury for the 34th America's Cup, in San Francisco. ... [more]  

Volvo Ocean Race: A warm and colorful welcome for Team SCA into Sanya by Richard Gladwell/Sail-World.com NZL, Auckland, NZ
The all-female crew, Team SCA, arrived to a warm and colorful welcome including fireworks, Chinese dragons, orchid garlands and traditional costumes into the city of Sanya on Hainan Island in southern China early Tuesday evening (local time). 'It was a really different leg. I wouldn’t say it was hard in terms of the physical side but it just had lots of things coming at all angles ... [more]  

Touch2Play had the great fortune of participating in what would be the largest yet gathering of J88’s to date. Quantum Key West Race Week would serve as a chance to see how boats lined up against one another in conditions that covered the full range. For this event we had Rob and Sandy Butler, Steve Leibel, Keven Piper, Coleen Walsh and myself, Larry Huibers. ... [more]  

As the Barcelona World Race leaders race to the Crozet Islands, once again their paths have diverged – Neutrogena around 200 miles to the south-west of first-placed Cheminées Poujoulat on the water, and gaining around 40 miles in the past 24 hours. ... [more]  

For the Tokyo 2020 Paralympic Games the International Paralympic Committee (IPC) will announce on Saturday (31 January) at 10:00 CET the final line-up of sports. ... [more]  

On a high octane first day of the ISAF Sailing World Cup Miami on Monday (26 January) Giles Scott, Alison Young and the Paralympian Sonar trio of John Robertson, Hannah Stodel and Steve Thomas saw the best possible start to their 2015 sailing seasons with double race victories. ... [more]  

On the opening day of racing at ISAF Sailing World Cup Miami, presented by Sunbrella, it was sunny and bright. It was storming and raining sideways. It was sunny and bright. ... [more]  

On the opening day of racing at ISAF Sailing World Cup Miami, presented by Sunbrella, it was sunny and bright. It was storming and raining sideways. It was sunny and bright. ... [more]  

RC44 World Championship Leg 1 - RC44 Valletta Cup preview
ISAF Sailing World Cup Miami - US Sailing Team Day 1
ISAF Sailing World Cup Miami -Finn class -testing conditions on Day 1
ISAF Olympic classes regatta Miami 2015 images by Ingrid Abery
Volvo Ocean Race: Team Alvimedica wins first podium place in Sanya
Volvo Ocean Race: Dongfeng scores historic victory for China
Volvo Ocean Race: Dongfeng release first DroneCam video from Leg 3
Volvo Ocean Race: Chinese team set historic first with home port win
Volvo Ocean Race: Team Vestas Wind arrives on time in Genoa + Video
America's Cup - Virgin considers backing Ben Ainslie, BAR
Bell's Beer Bayview Mackinac Race - Changes
Alpari World Match Racing Tour - Monsoon Cup preview
Barcelona World Race - A game of chase
Quantum Key West Race Week: Four GC32's make spectacular USA debut
Volvo Ocean Race – Frostad says Caudrelier proving them wrong *Feature
Volvo Ocean Race - Last day drag race to Sanya
Volvo Ocean Race Leg 3 - Tense onboard Abu Dhabi Ocean Racing
Volvo Ocean Race Leg 3 - Dongfeng Race Team pushing hard!
Volvo Ocean Race: Leg 3 Finish - Video - Delayed feed
2015 ISAF Sailing World Cup Miami - Countdown begins
Volvo Ocean Race: Donfeng set to create a piece of sailing history   
Barcelona World Race - First of the iconic Great Capes has been passed   
Classic 18fters racing on Sydney Harbour   
Volvo Ocean Race - Can Dongfeng still hang on for a Sanya win??   
Stephanie Roble, 2014 Rolex Yachtswoman of the Year   
Barcelona World Race - Taking advantage   
Oakcliff Awarded Joe Prosser Award at US Sailing NSPS 2015   
20 Nations head for 2015 St.Maarten Heineken Regatta   
Volvo Ocean Race - Less than 500 miles to go   
2015 Quantum Key West Race Week - Fantastic finish   
Barcelona World Race: Weather beacons launched midrace   
2015 Quantum Key West Race Week - Day 5   
Mount Gay Round Barbados Race – Gala prizegiving marks end of event   
2015 Quantum Key West Race Week - Day 5 images by Ingrid Abery   
Volvo Ocean Race Leader - Dongfeng - the right place at the right time   
ISAF Youth Match Racing World Championship - Notice Of Race online   
Volvo Ocean Race: Changes to Team Vestas Wind crew   
McDougall+McConaghy Moth Worlds: Highlight video released   
America's Cup: Oracle crew mate lodges complaint against Tienpont   
2015 Quantum Key West Race Week - Day 4 images by Ingrid Abery   


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 WAS US
LocalAds   DE  ES  FR  IT