Please select your home edition
Edition
Naiad/Oracle Supplier

Sailrocket 2 on the way to an outright world speed sailing record?

by Paul Larsen on 4 May 2011
SailRocket 2 sea trials Day 1 Vestas Sailrocket - copyright http://www.sailrocket.com
In 2008, Paul Larson and his Vestas Sailrocket was on the way to an outright speed sailing record when his craft crashed in a spectacular fashion, damaging it badly. It has been a long road back, but Vestas Sailrocket 2 has arrived in Namibia for their next challenge. The aim of the team is to beat the outright world sailing speed record.

The team currently holds the B-class (150-235 square feet of sail)speed sailing record with a speed over a 500m distance of 47.36 knots (87.71 km/h), but in 2008, before crashing, Sailrocket had reached a reported unofficial speed of 52.22 knots. (See the video the end of this article and relive the exultation with their speed achievement, watch the crash and then sympathise with Larson's devastation at his dream's destruction.)

Sailrocket 2's construction:
The revised craft was launched March 8 at an empty weight of only 275 kg/605 lb. Fabricated with materials from SP-High Modulus, the main structure is an autoclave-cured sandwich construction, comprising carbon fiber/epoxy prepreg skins over an aramid honeycomb core.

Prepregs included Gurit’s Ampreg 22, SE84LV and SE70 and some dry reinforcements. Its wing-like sail is built around a CompoTech carbon tube that acts as a spar. The wingskins are a polyester heat shrink film. According to Larsen, the entire boat, including rigging, has the equivalent aerodynamic drag of a 74 cm/30-inch diameter sphere, and its revised design enables the pilot to maneuver the craft in much rougher water than the first version could handle.

Here's the latest from Paul Larsen on progress, and see the end of the story for videos of their current testing and the spectacular crash of 2008:


Yesterday evening we had our third session of tow testing of the bare platform. It was a beautiful evening as we towed the wing-less platform up and down speed spot with the whole team taking turns in the boat and in the RIB in order to observe all aspects first hand.

We saw on our second session the day before that the addition of the first trial 'step' on the front float made a big difference to it's ability to release from the water and step up into planing mode.

The new second 'step' on the rear underside of the hull quickly ventilated from behind at speeds as low as three-four knots. This enabled the up forces on the front of the float to win the battle and start lifting the hull upwards as speed increased. This in turn allows the first original step to 'get access' to the air and also ventilate. Voila... the hull keeps lifting and we are planing.

We wanted to see this work first hand before we went and added them to all the three floats. The back float was hence still suffering and struggling to break free from the water. We tried a few other trials with foils up and down and the beam swung fore and aft before deciding to head back in.

Yesterday, we went back out with steps on all three hulls. The leeward hull is so lightly loaded without the wing on that the step really isn't necessary. I was hoping for a bigger change on the rear float. Whilst the step was an improvement, it seems that we still have a low speed where the aft float gets caught in the wave pattern generated from the front float. There is every chance that this might just be a phenomenon caused by tow testing and that the addition of the side force of the wing could break the whole 'loop' so we shouldn't get too concerned until we conduct some sailing trials.



It was interesting yesterday to watch the foil behaviour. We were typically towing at speeds around 15-17 knots. The fact is that the foil was virtually doing nothing and you could hear it rattling around in its locking mechanism rather than being forced against either the upward or downward limiters. When the foil is fully submerged when the boat is stationary, there is as much lifting area as there is downward pulling area. The effect is that when it has an angle of attack created by any side force i.e. a sail or a tow-line, the overall force is neither up or down.

You have to remember that the foils on our boats are actually pulling the boat down into the water. On most hydrofoilers the foils are there to lift the boat up and out of the water. On the Sailrocket designs, the angled/inclined wing does all the lifting and it is the foil that keeps us down. So... when we start off and the full foil is submerged, there is no 'net' down force from the foil but the wing is pulling up. As we accelerate and the wing powers up, it gradually begins to lift the boat up with it. This means that the foil rises and the top section comes out of the water only leaving the angled lower part in the water and this is the bit that does all the 'down' work. When the boat is hauling along at full steam, the back of the boat will naturally ride at the height where the up and down forces balance. If it gets 'bumped' too high then the balance will try and pull it down and visa versa.

This means we can only do so much towing the boat around without the addition of the actual sailing loads.

It sure was a beautiful evening. It was a perfect opportunity to let every other team member go for a ride. I really enjoyed seein Ben in the cockpit. It always surprised me to see boat builders spend so much time building boats only to see them go out the shed and the next set of plans come in. Surely the joy has to be in actually seeing what you have spent so long building in its element. This way you can truly appreciate what it is you are creating. It has to make the whole experience richer.

Helena was all concentration. She knows that she will have the option to pilot this machine for a record attempt at some stage... and she knows that that day may well be approaching. It's not talk anymore. What she does and how hard she pushes it is soley up to her. There will be no restrictions and if she wants to go for an outright attempt... then that will be her call. Yesterday she also got to drive it for the first time..



The only one missing was Hiskia... but he'll probably get his turn today.

The warm East wind was blowing lightly this morning which would indicate a nice but relatively windless day ahead. We will do one more session of tow testing where we will actually measure some of these loads... and then we will roll straight into the wing trials. We might be able to do both of these today if this wind settles a little so as not to corrupt the numbers.

I must admit that I am still a little concerned about the 'hump' drag. In respect to our situation, this 'hump' is the amount of drag that builds up before the boat makes the transition into 'planing' mode. You often see it in fast powerboats where they need to use a lot of power to get started but once they are up and planing on the surface of the water, they don't need so much power. This is because they have overcome this transition from low speed displacement mode to high speed planing mode. Some shapes do it better than others. We are discovering how big our 'hump' is right now and will try and use a few tricks to bend it to our will.

To follow the progress of Sailrocket 2, go to their www.sailrocket.com!website








The following video was taken during the 2008 record achievement and shows the spectacular crash:

North Technology - Southern SparsPredictWind.comZhik AkzoNobelb 660x82

Related Articles

America's Cup - Practice Session 4, Final day - on the water video
MyislandhomeBDA who has been doing an outstanding job with video coverage from Bermuda was invited on the water MyislandhomeBDA who has been doing an outstanding job with video coverage from Bermuda was invited on the water by Artemis Racing, and filed these reports on the final day of Practice Session 4 on the Great Sound, Bermuda. These videos are shot and produced by Jason Smith, who is living on the proverbial shoestring.
Posted today at 9:24 am
America's Cup - Artemis Racing emerging as Cup favorites
Out on Bermuda's Great Sound Artemis Racing are emerging as contenders to win the America's Cup Out on Bermuda's Great Sound, on a fast catamaran named Magic Blue, Iain Percy and his mates with Artemis Racing are emerging as contenders to win the America's Cup while honoring the memory of Andrew 'Bart' Simpson, who was killed in a training accident four years ago. Artemis is keeping Simpson in mind while quickly finding the sea legs it didn't get the chance to develop in the 2013 regatta.
Posted on 29 Apr
America's Cup - Spithill says valuable lessons learned this week
Oracle Team USA finished the latest practice week on a positive note with two wins in three starts in Friday’s races. Oracle Team USA finished the latest practice week on a positive note with two wins in three starts in Friday’s races. The end of the week saw moderate 10-knot Southerly conditions similar to what many are predicting for the America’s Cup race period in June. But earlier in the week, the winds were often closer to 20 knots, from the east, making for challenging conditions.
Posted on 29 Apr
World Sailing Show - Video news - May 2017 - Volvo 65, America's Cup
May 2017 edition of World Sailing News, which this month features Volvo Ocean Race, America's Cup and more May 2017 edition of World Sailing News, which this month features: Winding the clock back on a Volvo 65 and taking a race boat that already has over 40,000 hard miles under its keel might not be your idea of a perfect start for another lap of the planet. But the newly refurbished fleet of Volvo 65s are better than new. We went to Portugal to find out how this can be so.
Posted on 29 Apr
America's Cup - All six teams race together for the first time
All six America’s Cup teams taking part for the first time on the racecourse that will be used in the 35th America’s Cup More America’s Cup Class (ACC) practice racing has been taking place on Bermuda’s Great Sound, now with all six America’s Cup teams taking part for the first time on the racecourse that will be used in the 35th America’s Cup. Emirates Team New Zealand were the last team to arrive in the home of the 35th America’s Cup and raced for the first time today with a 2-2 win/loss record.
Posted on 29 Apr
America's Cup - Emirates Team NZ score two wins in first hit-out
After less than one week since the first sail in Bermuda, Emirates Team New Zealand joined their opponents on the water After less than one week since the first sail in Bermuda, Emirates Team New Zealand joined their opponents on the water for the last day of the latest round of the America’s Cup Class (ACC) practice racing. All six America’s Cup teams, now based in Bermuda, took part in a series of match races in 8-10 knots of breeze.
Posted on 28 Apr
28th May announced as the America’s Cup Endeavour Day
The America’s Cup Endeavour Program is the America’s Cup’s ambitious youth sailing and educational program The America’s Cup Endeavour Program is the America’s Cup’s ambitious youth sailing and educational program, dedicated to inspiring everybody who engages with the initiative and to leaving a sporting legacy in Bermuda that has a strong, positive impact on the community.
Posted on 28 Apr
America's Cup Champion forced out of Practice Race session + Video
Russell Coutts' comments following the conclusion of Practice Session 4 will be illuminating Five-time America's Cup winner, Russell Coutts' comments following the conclusion of Practice Session 4 will be illuminating. After the conclusion of four days of the five days scheduled racing in Bermuda, the Oracle Team USA CEO may find some of his comments on previous sessions coming back to haunt him.
Posted on 28 Apr
America's Cup - Close call as Emirates TNZ takes a nosedive in Bermuda
Emirates Team New Zealand was caught in a gust recorded at 24.3kts and nosedived today in Bermuda. With fresh winds forecast to ease later in the day, Emirates Team New Zealand left the harbour at the Royal Dockyard to head for a training session. She was caught in a gust recorded at 24.3kts and nosedived.
Posted on 26 Apr
America's Cup - Emirates Team NZ hooks up in Bermuda with Brits +Video
Emirates Team New Zealand were training again on the Great Sound in Bermuda, in fresh winds of over 25kts from the ESE. Emirates Team New Zealand were training again on the Great Sound in Bermuda, in fresh winds of over 25kts from the ESE. MyislandhomeBDA caught the America's Cup Challenger as they had their first real hook-up with another team - lining up against Britain's Land Rover BAR.
Posted on 25 Apr