Performance Redefined

Following a 15-month re-engineering project at Vitters, the 67m carbon ketch Hetairos made an impressive debut performance at the 2015 Rolex Maxi Yacht Cup. Four years after the yacht was first featured, TSR was invited to sail on board in Palma de Mallorca to experience the product of this overhaul and speak to the key personnel involved. Bryony McCabe reports.

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Initiated by a visionary owner who sought the fastest world-cruising superyacht at panamax size, the design process for Hetairos began back in 2003. Launched in 2011, Hetairos sailed thousands of nautical miles, including a transatlantic race in 2011 and a pacific cruise in 2013. Throughout this time the yacht’s performance potential was obvious, but was frustratingly beset with technical issues. Arriving at Vitters in the spring of 2014,  the project management team started the rectification project one step ahead of the game with Hetairos’ innovative and lightweight carbon structure.

The carbon ketch underwent extensive works, including the re-engineering and rebuilding of the propulsion system, the power generation and electrical systems, all hydraulics, waste-water and climate control, data networks and the control system.
The brief for project manager Patrick Yeoward of McMaster Yachts was to get the systems within this exceptionally built lightweight carbon structure running reliably to allow for her potential to be realised. “There was a very specific reason the boat was built – the owner wanted to go long-distance cruising but he also wanted to be able to race competitively,” Yeoward explains. “He has done both a lot in the past with his previous yachts; this time he wanted to do it with a boat that was really cutting edge.”
With the owner’s desire for a classic looking yacht, the performance of the boat is hidden away everywhere: from the painted faux-wood effect transom concealing carbon prepreg laminate underneath, to the yacht’s interior, which tells the story of a colonial trading ship with worldwide in influences.

No Mean Feat

“The hardest part of any yard period is that you are dealing within the confines of an existing structure, and there were certain parameters laid down during the build of the boat that we couldn’t adjust,” explains Yeoward. “it was effectively a reverse-engineering project – all within the confines of an incredibly lightweight structure.”

For Vitters, the project was a major contract outside their traditional reputation for new builds. While the majority of yard periods predominantly consist of a change of engines or generators, class measurements and a new coat of paint, the Hetairos project had some complex facets to it, which made it especially challenging for the yard team.

Report

“The propulsion technology, in combination with the hydraulic system, while keeping everything as lightweight as possible, were the unique points of interest for us,” reflects Louis hamming, managing director of Vitters. “it was an incredibly complex project and the experience and knowledge gained have been invaluable not only to the yard but to the superyacht industry as a whole.” “The propulsion technology, in combination with the hydraulic system, while keeping everything as lightweight as possible, were the unique points of interest for us.” – Louis hamming, managing director, Vitters
The boat arrived at the yard in May 2014 and this was the first opportunity the yard had to inspect it thoroughly. the team had visited it a few times to start the engineering process, but the complexity of the installation wasn’t evident until Hetairos arrived in holland and the team was able to take out all the floors and paneling in order to inspect the gear and see what had to be done.
With sailing performance key to the project, the team was under a great deal of pressure
to keep weight to an absolute minimum. “A shipyard is purely interested in building something that is 100% reliable and that can lead to over-engineering, so we had to persuade the team to a different way of thinking,” says Yeoward.

“As soon as you move one thing, you may be adding 10 kilos of weight through additional piping, couplings, brackets, mountings, cables or fluids and it all starts to add up. As it transpired, the yard rose to the challenge, grasped the owner’s philosophy with both hands and left no option out until they had found the optimal solution.”

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Power Generation and Electrical Systems

In its original format, the power plant on board consisted of four VW diesel car engines producing hydraulic power for propulsion, electrical power and hydraulic supply to the deck and sail handling equipment. All three consumers were supplied simultaneously from each engine but the control systems were allegedly not capable of keeping a faultless supply to one or all of them and frequent blackouts and breakdowns were reported.

In order to ensure reliable, safe, economical and long-term engine operations, two scania 405 engines and two separate generators for electric power were installed to break up all the power demands. With scania engines proven to be highly reliable, type approved and able to provide rated power with excellent torque characteristics and low fuel consumption, while also being able to operate under the required inclination angles of a sail boat, they were well-suited for Hetairos.

However, the Scania engines did not come without their compromises. “Because they are lightweight, if you suddenly get an extreme demand for power, you can actually stall them,” explains Yeoward. “We pushed the parameters in holland to understand the capabilities – you have to be nice to them – and that was part of the learning curve and configuration process.”

Alongside the engines are now two generators: one of 75kW that is solely an electrical supplier and the other of 90kW, which supplies both electrics and hydraulics. “the boat can be run on the small generator when motoring and for the majority of small manoeuvres,” advises Yeoward. “on the other generator there is a hydraulic pump and there is a balance between electrical demand and hydraulic demand. there is also a power management system to decide which is the dominant demand so that one can’t knock the other out.” the end result is a simple and trouble-free method of ensuring a constant power supply when required.

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Propulsion Concept

For Hetairos, thrusters provide more than a means to manoeuvre. the new engines drive a completely new design of retractable thruster pods, which are shaft driven directly by the engines, resulting in a very efficient propulsion system. the drive-legs have the ability to turn 90 degrees, meaning they act as the boat’s stern thrusters as well.

With maximum speed under sail being one of the key design parameters, using these drive-legs as main propulsion devices mounted in an inboard-box enables the yacht to reduce drag by retaining a clean, flush underwater shape when the drives are not being used, thus allowing the yacht to reach higher speeds.

The propellers, which have been custom-designed by Dutch propulsion consultants sip Marine, are forward facing, meaning they pull as opposed to push. There can be significant differences in terms of efficiency and power in choosing a pulling versus pushing propeller with a more pro led drive leg, but such was not the case with Hetairos considering the limited amount of volume available for the leg to fold into.

The most important factor for the propulsion system was to ensure enough bollard pull. “You don’t want to get stuck on a lee shore with this boat and you want to be able to get out of a nasty situation in serious wind,” explains Yeoward. “This can’t be done at high speed without causing serious damage, so this propulsion system enables enough low-end power.”

While this retractable drive-leg concept is not new, it has only existed on a much smaller basis. Going forward, the feature is likely to be in greater demand in the industry due to its impact on performance, but the decision has to be made very early on in the planning stages as volume has to be factored into the internal layout.

Hydraulic Systems

Because the duration of sailing manoeuvres depends on the speeds of the hydraulic consumers, such as winches and cylinders, a reliable high-performance hydraulic system is crucial on a boat with sailing expectations such as those of Hetairos.

The main factor in bringing the system up to the requirements of the consumers was enlarging the hydraulic ring main that ran around the whole boat in order to enable enough oil to supply these demands – essentially replacing the whole backbone of the hydraulic system on board.

Working from a plan produced by naval architects Dykstra for all sailing manoeuvres on the boat, the yard could fully understand the functionality that was required and was able to gear the hydraulic system to fit it. With the maximum flow requirement of the hydraulic system occurring while regatta sailing during gybing and tacking manoeuvres, the calculated requirement for the oil-flow during these manoeuvres goes up to 875 litres per minute.

The new power generation system ensures Hetairos has a system design and pump arrangement that accommodates both requirements for flow and power of the hydraulic system with only two engines running. Both engines have hydraulic pumps so they can be used for just the pumps, which generates a lot of power for the hydraulic demand.

In order to supply the hydraulics during racing – when there will be the most demand on the hydraulics – the engines sit in idle mode and rev themselves up and down according to load and the power take-offs are programmed to give the crew instant power, and plenty of it. The result has been a line speed on winches of two metres per second, with the ability to hoist the spinnaker in 50 seconds and impressive tacking and gybing speeds.

For Captain Graham Newton, the adjustment to the hydraulic systems is key to being able to fulfil the appropriate demands for racing the yacht, “particularly because you can control the speed of each winch,” he elaborates. “the functionality is incredible – in Porto Cervo the trimmer on the primary winch was actually telling us to slow down because they couldn’t tail fast enough.”

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The End Result

With these changes in place, the end result of building a boat of Hetairos’ size with such sailing potential is phenomenal. One of the most pivotal moments for the team was shortly after her relaunch in June 2015, in time for the Maxi Yacht Cup, where she famously held her own upwind against the latest and greatest monohull Comanche.

On a recent crossing, Captain Newton revealed that Hetairos hit a boat speed record of 31.8 knots in surf – the fastest speed reached since he’s been on board – in around 24 knots of breeze at a 135-degree true wind angle. The furthest 24-hour distance covered was 453nm, meaning an average of 18.88 knots. “We were sailing fairly conservatively and I think that with a full race crew, the right conditions and the correct motivation it would be possible to break 500nm in 24 hours,” adds Captain Newton.

“We wanted the boat to come out in all her glory and to get her to Porto Cervo for the Maxis was really quite an achievement – I think we surprised a lot of people,” concludes Yeoward. “It takes a very special type of person who is prepared to really teeter on the edge of technology and push everything and everybody.”
The result is one of the most remarkable sailing superyachts ever built – one that the whole industry can learn from.