sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
Sail-World.com : America's Cup: Predictwind - Better conditions for two races on Day 6
America's Cup: Predictwind - Better conditions for two races on Day 6


'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 more moderate winds winds will prevail for Sunday, Races 9 and 10 of the 2013 America's Cup. The first race starts at 1.15pm on Sunday, local time with the second race scheduled for 1415hrs.

Today we again 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 variations.

Officially the breeze is being forecast at 20-21kts. Today is the second 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 - maybe 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 20kts, 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 five 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 under the limit of 23 kts with the feeds showing 21kts.

Today there was no fog over San Francisco. Skies are clear and blue, meaning the air out to sea will not be as cold and likely to be sucked in to the same extent by the hotter inland systems, increasing the strength of the breeze. Peak breeze today is forecast to be 21kts - another indicator that winds during race time will not build further than forecast.

Wind map for September 15, 2013 San Francisco at 1315hrs - Start of Race 9 -  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 lowered intensity of the breeze in the actual race area, from yesterday - 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 15, 2013 San Francisco at 1315hrs - 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. 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. Winds are expected to start building at 1000hrs to a peak of 21kts four hours later.

Wind map for September 15, 2013 San Francisco at 1415hrs - Start of Race 10 -  PredictWind.com   Click Here to view large photo

The top image shows the wind speed and direction at 1400hrs with breezes expected to remain at 21ktskts at the start of Race 10 - these are only average speeds and gusts will be higher, maybe 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 10 - 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 Sunday and Monday. Typically the forecast for Monday 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 15, 2013 San Francisco for Sunday and Monday -  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 9 and the red dotted line shows the course recommended for Race 10. 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, however as the boats move to the top of Leg 3 the shoreside is more favoured, meaning that the lead boat will be encouraged to sail very strategically against the trailing boat as well as covering from a tactical perspective. The reason for the favour given to the shoreside is not clear, but is most likely to be a back eddy effect of the tide - which goes against the flow in the main channel. This effect is more pronounced in the second race of the day, sailed an hour later.

Downwind course projection September 15, 2013 - faint purple line is for Race 9, Red dotted line is for Race 10 -  PredictWind.com  


Upwind course projection September 15, 2013 - faint purple line is for Race 9, Red dotted line is for Race 10 -  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=114521

2:59 PM Sun 15 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

Artemis Racing took their development AC45 out on San Francisco Bay, yesterday. Videographer, John Navas was there to catch all the action on high resolution video. ... [more]  

2015 RC44 Championship Tour - With less than a month to go, eleven teams are eagerly anticipating the season-opener set to take place in Malta's renowned capital of Valletta, the historic 'City of Knights', from 25-29 March. ... [more]  

The 2015 US Grand Slam Series will take place within the month of August, beginning a couple weeks earlier and in a different order than previous editions. The Manhasset Bay Yacht Club, Bayview Yacht Club, Chicago Match Race Center, and Oakcliff Sailing organizers are pleased to announce that Requests for Invitation are being accepted now and all venues anticipate high demand. ... [more]  

A beautiful sunny Miami welcomed Star sailors to the first day of the 88th Bacardi Cup. One race is scheduled for each day of the 6-day event as part of the Bacardi Miami Sailing Week (BMSW) presented by EFG Bank. With winds around 10 knots from the East, the racing area was set about 1 ¾ miles south of Dinner Key Channel. The course is set at 95 degrees with two-mile legs, which will test sailors ... [more]  

It’s been a month since the International Paralympic Committee publicized its decision to drop sailing from the slate of sports at the Tokyo 2020 Paralympic Games. Since then ISAF has stepped up to lead the appeal for reinstatement. At US Sailing, we believe ISAF leadership is critical to our chances of overturning this decision, and we are pleased to see President Carlo Croce take this on himself ... [more]  

Top international photographer, Chris Cameron is working out of the Volvo Ocean Race Village in Auckland. ... [more]  

The first WWA Pro Card Qualifier presented by Malibu boats is set for March 22, 2015, hosted once again by Freedom Wake Park in Orlando, Florida. The WWA Pro Card events have been created to separate the top riders in the world and recognize them as elite. ... [more]  

NZ Rigging Supplied the Mast and Rigging package for Adrian Walters new Shaw 11 mtr 'Little Nico'. The mast is a High Modulus mast with internal locks on all halyards, internal mast jack, one piece Nomex cored box section boom, and composite rigging.cored box section boom, and composite rigging. ... [more]  

Barcelona World Race - As Cheminées Poujoulat climbed north out of the latitudes of the Roaring 40s and into a regime change on the east side of the South Atlantic high pressure system, leaders Bernard Stamm and Jean Le Cam are into relatively stable, quick downwind conditions which will allow them to make good miles north, ultimately to connect with the trade winds. ... [more]  

2015 Hobie 16 North American Championships September 20 to 25 at Pensacola Yacht Club. ... [more]  

Hobie Mid-Winter East - Ocean Springs Yacht Club April 10-12 2015. The regatta is open to all Hobie Cat classes ... [more]  

Choosing the northern route turned out to be a brilliant tactical decision. But not all decisions went so well. Because of one wrong gybe and changed weather patterns, Team Brunel lost its lead in less than a day. With only the Volvo Ocean Race tracker as a guide, it’s difficult for fans to understand how the Dutch team lost more than 80 nautical miles. Skipper Bouwe Bekking looks explains ... [more]  

RORC Caribbean 600 – Arguably the best fleet of offshore racing yachts that has ever gathered in the Caribbean, took part in the seventh edition of the event. 66 yachts started the 600 mile race around 11 Caribbean islands, with numerous world champions, America's Cup and Volvo Ocean Race sailors taking part with passionate Corinthian amateurs, many of whom are members of the Royal Ocean Racing Cl ... [more]  

This summer’s ‘must have’ tickets for The America’s Cup World Series, Portsmouth (ACWSUK) are officially available from Monday 2nd March. Fans and spectators are encouraged to book their place now to avoid disappointment with event organisers already receiving a large number of ticket and hospitality enquires. ... [more]  

SCYA's E.E. Manning Regatta 2015 – They had never sailed together until six months earlier when they stepped onto a boat that neither had ever sailed, but skipper Joseph Hou, 15, and crew Skylar Jacobsen, 14, squeezed out a remarkable victory Sunday in the Southern California Youth Yacht Racing Association's Shadden Series ... [more]  

Shawn Bennett of Tiburon, Calif. won the Long Beach Stop of the 2015 California Dreamin’ Series Sunday in this International Sailing Federation (ISAF) Grade three match racing regatta hosted by Long Beach Yacht Club and raced on the Long Beach Sailing Foundation’s fleet of Catalina 37s. ... [more]  

Sitting here in Antigua airport waiting for my flight back to London, life is good having just blasted across the Atlantic in just under nine and a half days on board the new Phaedo3 MOD 70, one of the fastest sailing boats 'in the world'... ... [more]  

In November of 1994 Yachting Magazine consultant Gary Jobson asked Peter Craig, 'how hard can it be? Just raise some flags and blow off some guns.' And so began Craig's involvement in what was then a 112 boat - single division regatta that would soon evolve into an iconic annual international keelboat event. Yachting Magazine founded Key West Race Week in 1987. ... [more]  

Serious Fun! That's what participants, sponsors and onlookers are expected to have during the 35th St. Maarten Heineken Regatta which will be held in St. Maarten during March 05 - 08, 2015. The Regatta is considered to be the biggest in the Caribbean and offers a great combination of challenging races and fantastic gatherings under the banner of 'Serious Fun'! ... [more]  

Barcelona World Race – After the limits of the southern oceans imposed by the combination of the weather systems and the safety barrier of the Antarctic Exclusion Zone, the Atlantic is opening up for the top trio. ... [more]  

Images from Auckland of the media conference on Sunday and prizegivings for Leg 4 ... [more]  

At the media conference held the morning after the finish of leg 4 of the Volvo Ocean Race, Mapfre skipper Xabi Fernandez announced that regular skipper Iker Martinez will be back on board for the next leg and most of the remainder of the race. Fernandez had taken over the role, skippering Mapfre to a 4th place on Leg 3 and a win on Leg 4. ... [more]  

Miami Sailing Week (BMSW) presented by EFG Bank will kick off with 173 boats traveling to Coconut Grove to compete in the 88th Bacardi Cup ... [more]  

Volvo Ocean Race: Leg 4 finishes at night after a tense day *Feature by Richard Gladwell, Sail-World.com NZL
The finish was more like that of a short 100nm race around the Hauraki Gulf. Instead, the first three boats to cross the finish line at the end of Leg 4 of the Volvo Ocean Race arrived mid-evening. ... [more]  

Farr 40 International Circuit - Alex Roepers doesn't like to dwell in the past. However, when prompted, the New York businessman will talk about the magical run he and the crew aboard Plenty enjoyed during the 2014 Farr 40 International Circuit. To the contrary, the thrill of victory only made Roepers and the Plenty team hungry for more. ... [more]  

Coast Guard crews continue the search Monday for Richard Byhre, the 76-year-old sailor who did not return from his sailing trip as expected. ... [more]  

The International Sonar Class is pleased to announce that Shumway Marine, with the cooperation of designer Bruce Kirby has made arrangements to have the Sonar built by Rondar Race Boats in the U.K., with plans eventually to have the boat built on both sides of the ocean. The American Rondar facility is in Peabody, MA. Rondar, expects to launch its first Sonar in April. ... [more]  

Rio de Janeiro's state environmental agency says it is investigating a fish die-off that has left thousands of carcasses floating in waters where sailing events are to be held when Brazil hosts next year's Olympics. ... [more]  

This year's 35th edition of the St. Maarten Heineken Regatta is nothing less than an island-wide effort. Besides the sponsors, countless volunteers and the numerous local organizations that offer their excellent services, the Regatta Organizers would like to say special thanks to the hotels which are so generous to donate complimentary hotel rooms for the St. Maarten Heineken Regatta. ... [more]  

Volvo Ocean Race: Images ashore after Leg 4 by Richard Gladwell, Sail-World.com NZL
Sail-World's NZ Editor, Richard Gladwell, was on the water and ashore for the finish of Leg 4 of the Volvo Ocean Race, and provided this gallery of images after the first three boats had docked. ... [more]  

Volvo Ocean Race: Images from the finish of Leg 4 by Richard Gladwell, Sail-World.com NZL
Sail-World's NZ Editor, Richard Gladwell, was on the water for the finish of Leg 4 of the Volvo Ocean race, and captured these images from the final few miles of the race, and on the dock. ... [more]  

O MAPFRE conquistou de maneira emocionante a quarta etapa da Volvo Ocean Race, disputada entre a China e a Nova Zelândia. Na manhã deste sábado (28), o barco espanhol cruzou a linha de chegada em primeiro após quase 21 dias de navegação. ... [more]  

RYA Suzuki Dinghy Show - a British tradition by Rob Kothe and Jedda Murphy
Our favourite boat show in the whole world is the RYA Suzuki Dinghy Show. It is like no other, with a large percentage of eight to 15-year olds, with many young siblings often dragging their parents down the aisles. Its a dull overcast day in Lonon with rain showers, but inside the heated halls of the Alexandra Palace, the fabled 'Ally Pally' , around 5,000 visitors will gaze at touch and feel ... [more]  

Eight minutes between Podium players as Spanish win VOR leg 4
Volvo Ocean Race - Leg 4 - fleet arrives in Auckland and the winner is
Volvo Ocean Race - Leg 4 - the fleet approaches Auckland
Volvo Ocean Race - Less than 10 miles to Auckland finish
2015 RORC Caribbean 600 - Third time lucky for happy Hap
Volvo Ocean Race: Leg 4 Finish - Auckland - Live Video and Updates
Barcelona World Race - Neutrogena crosses Cape Horn with 40 knots wind
St. Maarten Heineken Regatta - Natty Rico will close the final night
Barcelona World Race - At Cape Horn memories are made. and recalled
Big winds for SCYA Manning Regatta at ABY Club
Hutchinson and Roble honored at US Sailing’s Rolex Awards ceremony
Finn World Masters Championships 2015 - Pre registration open
Registration for the 2015 Finn European Championship is live!
RORC Caribbean 600, day 4 – Classic Focus and Four Figaro II teams
Hutchinson, Roble honored in New York as Best of 2014
Barcelona World Race - Pedestrian Pacific, Atlantic highway to home
America's Cup: Artemis Racing lines up against Oracle Team USA - Video
High Performance Yacht Design conference during Volvo OR stopover
Volvo Ocean Race: Ryan Houston - How Alvimedica's chemistry works *Feature
Volvo Ocean Race: Dave Swete - Alvimedica's race so far *Feature
Volvo Ocean Race 2015 – No sleep until Auckland   
Etchells NA Midwinter East Series - Schoonmaker Cup preview   
RORC Caribbean 600 day 4 – Close competition – 43 yachts still racing   
Volvo Ocean Race: Team Alvimedica hopes to use Coastal Classic tricks *Feature   
AC45 Turbo Training - Oracle Team USA images by pressure-drop + Video   
America's Cup: Emirates Team New Zealand gears up on less money *Feature   
Volvo Ocean Race – The race tightens as New Zealand looms   
AWT Goya Pro Cabo Verde kicks off in style!   
Barcelona World Race - Two different worlds separated by Cape Horn   
America's Cup: Barker offered non-sailing role by Emirates team NZ   
2015 CYC Midwinters Race – Pictures by pressure-drop.us   
CYC Midwinters Racing – Bring On The Breeze! – Overall   
Laser World Championship – Over 2000 sailors to race in Kingston   
Volvo Ocean Race: Barkow and Lush - from the Olympics to the Volvo *Feature   
Volvo Ocean Race 2015 – Its anyone's race - Leg 4 to Auckland   
Barcelona World Race - A time for extra care and caution   
2015 RORC Caribbean 600 - Phaedo3 breaks record   
Barcelona World Race - Cheminées Poujoulat pass Cape Horn   
2015 RORC Caribbean 600 - Records predicted to tumble + Video   
2015 ISAF Women’s Match Racing World Championship - NOR released   


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