VESTAS Sailrocket 2 sets its sights on world speed sailing record
By Darren Quick
November 21, 2011
If floating along in a boat propelled only by the gentle push of an ocean breeze is your idea of relaxing, then you might want to steer clear of the aptly named VESTAS Sailrocket 2. Designed and built from the ground up with a focus on speed, the boat and the VSR2 team have headed to Walvis Bay in Namibia with the aim of breaking the outright world speed sailing record for the short distance 500 meters (1,640 ft) of 55.65 knots (64 mph/103 km/h) set in October 2010 by American kite-surfer, Rob Douglas.
In 2008, the original VESTAS Sailrocket 1 boat hit speeds of over 52 knots in Walvis Bay, Namibia, and still holds the "B" class record but failed to clinch the outright record before flipping as it approached record-breaking speeds. The team aims to rectify this with the second generation Sailrocket that was designed to be significantly faster than its predecessor.
"We learnt a lot with the first boat. The recent performance of the kite surfers vindicated our decision to build a new boat. I'm confident that Sailrocket 2 has the potential to take the record to new levels," says project leader, Paul Larsen.
Since the VSR2 team set its sights on the outright speed record nine years ago, the record has increased by nine knots but the VSR2 team thinks they now have the boat to set a new record.
The boat itself doesn't look like anything you're likely to see at your local marina. Its main fuselage and beam are angled at 20 degrees to the direction of travel so that the boat points directly into the direction of the "apparent" wind to reduce drag and increase stability at high speed. The team claims that the entire 12.2 m (40 ft) long and 12.2 m wide boat - including the rigging - has the equivalent aerodynamic drag of a 74 cm (29 in) diameter sphere.
The boat's wing has an overall area of 22 m2 and sports a number of new features to make it more efficient and stable. It is thinner than the wing used on the VSR1, weighs around 65-70 kg (143 - 154 lb) and is inclined at 30 degrees to match the inclination of the opposing foil on the other side of the boat. Since the boat only needs to sail in one direction, the wing is asymmetrical and set up for a starboard tack to suit the Walvis Bay location where the record-breaking attempt is being made.
To counteract the side-force of the wind and stop the boat slipping sideways, sail-powered boats such as VSR2 rely on fins or "foils." However, at speeds of around 60 knots, traditional teardrop profile foils experience a phenomenon called "cavitation," which occurs when a liquid is subjected to rapid changes in pressure resulting in the formation of cavities where the pressure is relatively low that can cause a lot of drag and loss of stability.
To overcome this problem, VSR2 can employ special ventilated foils shaped more like sharp wedges where only one surface is used at a greater angle that allows the craft to exceed the limits imposed by cavitation. The team says many high speed power boats use propellers with this kind of profile but it has never been done effectively on a sailing boat. The team hopes VSR2 will confirm the performance of ventilated foils and mark a significant step in the evolution of speed sailing.
VSR2 was launched in April this year in East Cowes, Isle of Wight, UK, before being shipped to Namibia for initial trials and system checks that saw the boat sailing at speeds of up to 40 knots (46 mph/74 km/h). In her first 500 m run on October 19 the boat reached a speed of 54 knots (62 mph/100 km/h) in winds of around 30 knots (35 mph/56 km/h).
With the months of September through December providing the best winds off the coast of Namibia, the VSR2 team has just commenced 28 days of attempts to break the world record under the watchful eyes of a World Sailing Speed Record Council (WSSRC) official. Their progress can be tracked on the VESTAS Sailrocket site.
Here's a video of VSR2 on a trial run in October.
Images courtesy VESTAS Sailrocket