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Image courtesy of Reichel-Pugh. Winning sled Pegasus cuts a fine line through Californian waters prior to the start of the 41st Los Angeles to Honolulu Transpac. This sled and two of her sisters - the trio designed by San Diego firm Reichel-Pugh - dominated Division One. Close competition! A trio of similar sleds dominate Transpac 2001 July, 2001 You could be forgiven that Transpac 2001 was a sponsored promotion for San Diego yacht designers Reichel-Pugh. Effectively the high was split in two and in the case of trade winds, two smaller systems are not better than one. Light air start Winds were almost non-existent at the start on July 1. By dawn the next day the trio were wallowing in the North Pacific, any dreams of breaking the course record evaporating with the rising sun. Hitting the ridge As Stan Honey explains in his routing notes, the first hurdle after leaving Catalina Island to port is judging where to cross the ridge of high pressure. According to winning navigator Mark Rudiger, aboard Pegasus, that ridge was 'softer' than normal and compounded the leader's problems by moving away to the east just as the rest of the fleet arrived. The leaders spent longer in the light airs while those behind weren't in them for very long at all as trades filled in. As Rudiger explains, high pressure systems rotate - elongating and compressing depending on the influence of low pressure north and south. As the leading sleds in Division One approached the ridge it was at its weakest cycle. Then, as those in front sailed out of it, the ridge accelerated and moved rapidly east, rolling over the tops of those boats behind. "Normally those in front come out of the ridge and squirt ahead," Rudiger recalls. "This time everybody remained closer together." Rudiger's next call was to sail on port pole and get south as the high moved south-east, with the aim of staying in the region of greatest pressure - or gradient wind. Keep in mind here that winds were east-south-east, so Pegasus' boom would have been out to starboard, or to the right, and her spinnaker pole would then point to port, or to the left- thus the term 'port pole'. As it turned out, winds in the north remained fine as the isobars on the high's southern quadrant compressed against low pressure north of the equator. Pegasus' dig to the south was a mistake, notes Honey, who remained on a lay-line for Honolulu from the time Pyewacket exited the ridge. While Rudiger and Pegasus jibed and sailed north to take advantage of winds shifting to the right, Pyewacket held her lay line. Together with Chance, the third Reichel-Pugh sled, the dominating trio of Division One came together and a drag race for the finish ensued. Playing the squalls Honey notes that winds ahead of squall clouds tend to converge as they are sucked up into updrafts preceding these mini-weather systems. Wind gusts, on the other hand, diverge in direction as the wind hits the sea surface and spreads out. Average winds in squalls veer about 15 degrees to the right of the prevailing surface wind while behind these clouds winds can be dreadfully light - especially near dawn. Honey recommends grabbing any squall within reach when sailing aboard fast sleds. He says jibe back and forth in front of the squall - and yes each jibe back towards the squall will be at a terrible angle because of the way the wind converges, or 'toes-in' in front of the updraft. Finally, Honey notes that exiting the squall on port poll will make your escape smoother. As squalls tend to move to the right of prevailing surface winds, jibing away from one of these blustery beasts on port pole will help to avoid getting caught behind and in light airs. Image courtesy of Reichel-Pugh. Basic and lightweight: The interior of winning sled Pegasus shows off a Spartan beauty that is the hallmark of modern race yachts. Playing a game of chance It seems Pegasus, Pyewacket and Chance together played these squalls with various outcomes. Mark Rudiger, aboard Pegasus, notes that squalls remain unpredictable even to experienced eyes. "Sometimes they're forming, sometimes they're diminishing," he says. "Sometimes they move predictably, but then as they climb and their tops touch upper level winds they change direction and that's a hard one to call. "It really comes down to who wins the most squalls. If you're in the lead you don't want any - you want nice and steady conditions, but if you're behind you're looking for squalls all the time." Rudiger recalls that as the three Reichel-Pugh sleds played games of cat-and-mouse, each one suffered at the hands of these beautiful, bouyant clouds. At one point Chance took the lead and fell into a squall. Pegasus and Pyewacket jibed out and the leader failed to cover. Come morning Chance was behind, looking at the transoms of her sister sleds. The next day Pyewacket went to windward of a squall while Pegasus took the leeward angle to her eventual benefit. At the same time, Honey notes that as Pyewacket was on her lay-line for Honolulu, she was unable to play the squalls as effectively. "Pegasus had a better line through squalls than us
as they were 15 miles to leeward," recalls Honey. "All we could do was
go straight for the finish." "I love to grind, and drive and whatever. That's part of the fun," he says with obvious enthusiasm. "I think in the end we tired the others out. We ground them down." Honey, meanwhile, reckons the newer Pegasus had a six to seven mile per day advantage over Pyewacket. "We sailed a faster course," he notes. We were sailing our downwind angles, but as we were on our lay line we were unable to jibe to effectively use the squalls. In the end, the brand-new Pegasus grabbed the Barn Door trophy one hour and three minutes ahead of Pyewacket - about 16 miles behind. Bob McNulty's Chance finished third, 90 minutes behind Pyewacket. Whatever the outcome, it was a remarkably close finish after eight days and 2225 nautical miles of competitive sailing. More of it, we say! © Jamie Brown/weather-wise.com 2001 A look at the weather North East Pacific winds derived
by radar (Quickscat) Image © NOAA This composite image shows Hawaii at the bottom left and California at the top right. The red line is an approximate rhumb line between Los Angeles and Honolulu. There's plenty of wind west of San Francisco and Oregon thanks to Pacific high pressure butting up against low pressure over the US western States. The red arrows there show 30 knots in places. But look to the south and there's little wind. Blue indicates a breeze in the 10 knot range, light blue in the order of five knots. Green shows wind about 15 knots and yellow indicates a breeze in the low 20s. North of Hawaii a low pressure trough is creating havoc with the normal trade wind scenario. Surface winds are veering right around to the south- west before backing all the way east. The pressure map below also highlights how wind circulated around this trough. For a larger view of this QuickScat click on the image. Surface pressure Image © Ocean Weather The North Pacific High in this image is clearly split in two as a low pressure trough north of Hawaii influences wind at the surface. Click on the image for a larger view. North Pacific infra-red This animated infra-red image is enhanced with overlays of surface pressure and wind direction. There is a very weak ridge on the south-east corner of the high, and a major low pressure trough north of Hawaii creating light winds at the surface and disrupting trade wind flow. You can see how consistent the Los Angeles to Honolulu route can be over 48 hours, and this is when the North Pacific High is in major disruption! The real trick to winning Transpac races is understanding the subtlety of winds along the way, and playing them to your advantage. North Pacific jet streams Image © Aviation Weather Centre This image shows the location and strength of jet streams over the North Pacific. Not a lot of dominant activity! A reasonably strong jet of 100 knots curves sharply over the Bering Sea, but is too short to create a solid storm track. The jets north of Hawaii mirror a trough of low pressure at the surface. The result is a weaker-than-usual high pressure cell over the North Pacific. Hot links for the central and east North Pacific Surface pressure: Composite surface pressure and infra-red images courtesy of the University of Hawaii. Surface pressure for the eastern North Pacific thanks to Ocean Weather. Pressure data taken from the National Center of Environmental Prediction's Aviation Model. These maps are plotted every 3 hours, and are available approximately 1 hour after valid time. Satellite images: Animated satellite images of the NE Pacific: Intellicast (a division of Weather Services International) offers this infra-red image of the eastern North Pacific, showing Hawaii and the Gulf of Alaska. Cold cloud tops - indicating heavy rain or snow - are coloured dark red, warmer cloud tops - showing less precipitation - are coloured light yellow. Intellicast also offers an animated loop of the eastern Pacific. Animated loop of the Central Pacific - specifically Hawaii, thanks to Weather Services International and Yahoo. This image shows high cloud tops better than surface clouds, but is good for tracking major weather events. Surface winds: Surface winds in the North East Pacific using 'quickSCAT' satellite technology. Surface winds in the vicinity of Hawaii Wind analysis from the University of Wisconsin showing surface, upper and jet stream - or water vapor - winds. As well, there are charts showing wind shear and upper level divergence. For the arm-chair sailor, the low-mid level infra-red winds tell an awful lot about the sea state where the boats are. Colour-coded arrows report wind strengths and direction at different levels. Remember: Friction at the surface slows the wind down a bit, so it will never be as strong at wave height as it shows on the 900hPa chart. Upper level winds: The Aviation Weather Centre offers these terrific flight level charts SIGWX) which show the position of jet streams over much of the globe (mostly Northern Hemisphere). Because upper level winds, like the jet stream, steer our weather systems, knowing where these winds are and how they are behaving helps us to understand whether systems are moving east to west quickly or whether they will stalling because of a kink in the pipe-line. Comment: The National Oceanographic Data Center in Hawaii issues this great surf and wind forecast for Oahu, thanks to Pat Caldwell. Wave models: Scripps University offers this animated 72 hour forecast of significant wave heights for the entire Pacific rim. Tropical storm info: For tropical storm information around the Hawaiian Islands, the Central Pacific Hurricane Center is a good place to start. Hawaiian weather information thanks to NOAA. More great reading: Follow the Transpac through the official site. Visit the home of Reichel-Pugh - designers of the winning turbo sleds in this race, and countless others. Open 60 trimerans: Follow the Challenge Mondial Assistance through the official web site and get a preview of weather conditions on the route. Re-live the solo trans-Atlantic race of June 2000 and the Quebec to St Malo of last August. Open 60 monohulls: Catch up on all the past action of the recent Vendee Globe in our race archive. The world's biggest catamarans: Re-live the action between the world's fastest multihulls in The Race The world's toughest ocean race: Re-live the 2000 Sydney to Hobart yacht race! The world's wildest winter wonderland: Break ice in the Ross Sea! |
