Superyachts: "Nilaya" - a blissful home on 47 metres

Black or silver was the first question to be answered at the start of the project. It was not about the colour of the hull, but about its material - a fundamental question for sailboats over 40 metres in length: aluminium or carbon? With a length of 47 metres, "Nilaya" is positioned at the upper limit of what carbon fibre constructions can achieve. "My 34-metre (all-carbon) Baltic was a fantastic yacht that we sailed around the world and won many regattas with," says the owner of "Nilaya". "During the twelve years with her, I realised what the next one should be like: comfortable and fast enough to win superyacht regattas."

"Nilaya" means "blissful home" in Sanskrit

The list presented by project manager Nigel Ingram from MCM Newport Nauta Design and Reichel/Pugh was long and well thought out. As comfort for the client also means low noise levels below deck in addition to increased space, he decided to have the hull built from aluminium: "We wanted her to be quiet - a crucial characteristic when it comes to the quality of life on board - also for the crew." Apart from the acoustic advantage, the impact resistance of the material and the ability to have repairs carried out easily in almost any part of the world also speak in favour of metal hulls.

More about the "Nilaya":

• Royal Huisman docks the new "Nilaya"
• "Nilaya" christening ceremony in Amsterdam
• New 47-metre slipway glides across the North Sea

Basic question: carbon or aluminium? Both!

Now shipyards that produce composite super-sailors - the longest carbon hull measures 60 metres - are showing ingenuity in minimising noise emissions. In addition, the highly rigid and strong fibres have a higher interior volume, which results from thin-walled hull shells with few stiffeners. The greatest asset of high-performance fibres is generally considered to be their low specific weight.

Mario Pedol from Italian design studio Nauta, who worked with US designers Reichel/Pugh for the second time on this project, dispels a myth: "I thought an aluminium hull would weigh 60 to 70 percent more than one made of carbon, but the weight of the hull and deck only makes up about 15 percent of the total weight of a sailing yacht."

In the end, it wasn't quite possible without the black fabric mats. And it is not surprising that the aluminium specialists from Royal Huisman were chosen. The long-established company from Vollenhove processes aluminium like no other shipyard and still welds its hulls from the alloy Alustar in its own halls. Composite components are supplied by neighbouring and sister company Rondal. "Featherlight" is what the Dutch call the hybrid construction of fibres and light metal first tested on "Nilaya". The 17.50 metre long monocoque comprising the body and cockpit is made entirely of carbon fibre.

Radically beautiful hull shape from Nauta and Reichel/Pugh

The carefully curved deckhouse shows that Nauta Design has also broken new ground in terms of design. Just look at the huge leap of the deck! The only difference is that it doesn't follow a classic arched curve, but a more linear gradient. This is no less pleasing to the eye, but takes away a further element of massiveness from the already quite flat hull.

The length-to-width ratio of 4.5 has remained the same as its predecessor, but the new model is much wider at the rear. The widest point measures a full ten metres at cockpit level. The stem is now almost vertical and the waterline is considerably longer and narrower at the same time. This dramatic drop in the lower circumference at the stern is made possible by a soft chine that rises just behind the bow and flows into the top of the stern.

Less wetted surface increases the gliding potential, the high width of the deck increases the dimensional stability. Nilaya" showed that this works during initial tests off Mallorca after delivery. Jim Pugh reports: "That was a truly astonishing performance for a superyacht. Although we only had ten knots of true wind, the speed of response was remarkable. This yacht will cause a stir wherever it goes, but especially on the Bucket." This refers to the unofficial world championship for high-tech sailing yachts over 40 metres long off St. Barths at the end of March.

11.6 knots on average on the flyover

The 47-metre yacht arrived in the Caribbean with its owner on board, who has sailed dinghies since his childhood and, after a Swan 48, several Nautor yachts. His conclusion after the Atlantic crossing: "I have to admit that the yacht is very comfortable and fast." "Nilaya" completed the 2,775 nautical miles in ten days, mostly in three to four force winds and with an average speed of 11.6 knots. The top speed was over 20 knots. The polar data from the Velocity Prediction Programme (VPP) predicts almost 18 knots at a wind angle of 90 degrees in a breeze of 15 knots.

Even in light winds, it should move quickly and the engine should rest as often as possible. The flared top of the mainsail catches the wind at a height of up to 63 metres, with Rondal producing the mast in one piece using the out-of-autoclave (OOA) method. The prepregs of the 21-metre-long furling boom, which extends aft in a streamlined manner like an aircraft tail, underwent the same curing process without pressure but at a high temperature. The shape of the spreaders also follows the principle of minimum drag - in addition, the spreaders, which are concave towards the bow, allow the J2 to have a slightly longer lower leech. Elliptical carbon shrouds from Carbolink are also a consequence of flow simulations.

America's Cup expertise was incorporated into the design

For the underwater CFD studies, Reichel/Pugh co-operated with the America's Cup specialists from Caponnetto Hueber and Giorgio Provinciali. Twelve models were run through the digital shipbuilding test centre on the way to the final hull form. Jim Pugh is convinced: "It is in no way a further development of its predecessor - our knowledge base has expanded dramatically. New CFD hydro tools provide far more accurate calculation results, both in shallow water and in waves. This design is the beginning of a new era in superyacht design."

Royal Huisman's designers, who came together in a large room for finite element analyses (FEA) - an approach based on the methodology of the European Space Agency - were also occupied with huge amounts of data. This made it possible to predict how a component or neighbouring elements or an entire yacht would react to stresses such as load, force, heat or vibration: a kind of digital prototyping - only faster and without the need for physical models. One consequence was individual spacing of the hull frame to maximise rigidity and minimise displacement.

Many weight savings in details

The FEA sessions resulted in weight budgets for individual sections and the use of carbon for tubes, the box of the lift keel (4.50 to 6.90 metres), the rudder stocks or the recessed tender bay on the foredeck; in some cases, composite elements were bonded to bulkheads and door frames. The carbon hatches are closed by titanium bolts that connect carbon rods on the inside for simultaneous unlocking. The heating, ventilation and air-conditioning system was reduced by 600 kilograms, and the masthead by 50 kilograms. Tapered on all four sides, this resulted in a supposedly small gain - but in a crucial area. Reducing the teak deck thickness from an average of 15 to nine millimetres saved 1,300 kilograms.

The fact that the backstays are held in position by locks and hydraulic cylinders - a request from the owner - saves .1200 kilograms and three to four cubic metres of volume in the lazarette compared to the typical arrangement with captive winches. Where automatic furling and hauling assistants are used, they are hybrid formats for pulling forces of up to 18 tonnes. They rely on aluminium housings and carbon drums and weigh only half as much as conventional metal models. In addition, the diameter has been reduced from 600 to 450 millimetres, resulting in a weight reduction of 890 kilograms.
The drive system has been lightened by 2,000 kilograms and focuses on flexibility instead of mass: the Scania engine, which weighs around two tonnes, is supported by an electric motor and two variable-speed generators. The battery pack enables low-noise operation and load peak capping.

Royal Huisman produced a 1 : 1 mock-up of the cockpit

The equipment diet resulted in an overall weight reduction of three per cent. The hull was eleven percent lighter than pure aluminium. For the interior, Royal Huisman used sandwich construction with foam cores and thin wood veneers. Nauta Design worked with the owners' designer, May Vervoordt, to develop the interior of "Nilaya", which means "blissful home" in Sanskrit. The result is a mixture of contrasting woods, light-coloured upholstery and muted shades of blue and terracotta for the sofas and cushions.

"Elegant and sophisticated materials blend gently with the natural light to create a truly cosy environment," says Pedol. The owner's suite is located at the very front, followed by the VIP cabin and TV lounge, followed by the main saloon, two guest cabins, the galley, crew mess, navigation and four double crew cabins. (Unfortunately, we are not allowed to show the interior fittings in this article).

Essential for the deck design by Pedol and his team was a mock-up, which was created from wood in Royal Huisman's paint shop. Proportions and arrangements were tested for ergonomics and walkways under simulated heeling angles. As a result, an impressive coaming protects the guest cockpit, and the working area behind it benefits from a wide bulwark, to the inside of which the wheels are attached. The far-out steering position guarantees the best visibility, but also dizzying positions when the boat is in a strong position due to its width. You don't have to give in to this in the cockpit: The seats unfold from the canopies and can be tilted up to 30 degrees.

"We wanted innovative technologies, but nothing experimental," summarises the "Nilaya" owner. This includes a steering system with separate cables and carbon push rods to move the 47 metres with precision and without fatigue. Rigging project gear hubs integrated into the two wheels reduce the steering forces by up to 25 per cent if required. This allows the aluminium-carbon construction to react more quickly downwind, for example to better steer waves. At the cross, you can shift back for full control. Like so many things on board, the rudder also combines the best of both worlds.

Technical data "Nilaya"

• Overall length: 47.00 m
• Length waterline: 45.00 m
• Width: 10.00 m
• Draught: 4.50-6.90 m
• Material: aluminium, carbon
• Sail area downwind: 1,269 m²
• Sail area downwind: 2,141 m²
• Sails: Doyle Sails
• Rig and sail systems: Rondal
• Mast height: 63.90 m
• Engine: Scania DI 16 090M 640 kW
• Electric motor: 180 kW
• Battery capacity: 180 kWh
• Generators: 2x Volvo D4-175 129 kW
• Fuel: 15,000 litres
• Range @ 10 kn: 2,750 nm
• Navigation: B&G, Garmin
• Construction: Reichel/Pugh
• Exterior design: Nauta Design
• Interior design: Nauta Design
• Class: Lloyd's SSC

Other interesting superyachts:

• "SEA EAGLE": The largest aluminium sailing yacht in the world
• CNB 78 "ONE": Solaris' new arrival - a masterpiece of the art of sailing
• The largest sailing yachts in the world - places 1-25

"Nilaya" in the video