Rondal played a pivotal role throughout the design and engineering loops of the Nilaya project as well as building the deckhouse, cockpit, keel trunk, rig, sailing systems and more

Who do you call when you have a groundbreaking new concept for a superyacht that requires a performance rig, integrated sailing system and a wide range of carbon components? For the 47-metre (154ft) Reichel/Pugh-Nauta sloop Nilaya, the choice of a partner with the required expertise in design, engineering and fabrication of hitech sailing systems and marine carbon composites was obvious. It was a job for Rondal.

Constructed at the Royal Huisman shipyard in The Netherlands – the first yacht produced with their innovative new Featherlight methodology – and due for delivery to her owners around the time this issue of Seahorse went to press, the new Nilaya is by a clear margin the lightest-displacement aluminium sailing superyacht ever built. Her polars suggest that she’ll be quite capable of challenging carbon composite superyachts in bucket regattas, even though she is primarily conceived as a longdistance cruiser.

Selected to produce the carbon fibre components of Nilaya’s hybrid hull, as well as supplying her highmodulus carbon mast, furling boom, fully integrated sailing systems and more, Rondal was involved in the project from an early stage onwards. Engineers from Rondal played the key role of sailing system integrator in Royal Huisman’s finite element analysis (FEA)-driven Featherlight approach, ensuring the optimisation of all the carbon composite components in the hull and deck, as well as the entire rig, and supporting the process throughout.

Many of the aluminium-hulled superyachts built in recent years have some carbon components but Nilaya takes it to a whole new level. Her keel trunk, for example, is a complex structure with laminations that are more than 65mm thick, manufactured with extreme precision – tolerances of 0.3mm – to ensure that the yacht’s ultra-high aspect lifting keel can operate smoothly, even when sailing upwind when it is subjected to very high loads.

The carbon mould for the keel trunk was precision-milled across complex contours and the final component required multiple cures, due to the unusual depth of laminations that was needed to create a structure strong enough to withstand the colossal forces that could potentially act upon it if the yacht were to run hard aground. Even so, the end result is a remarkably slim and ultra-lightweight keel trunk that contributes a significant weight saving to Nilaya’s displacement while also having a minimal impact on the yacht’s internal layout and interior design.

Above: Rondal’s new captive reel winches weigh only half as much as their equivalent predecessors

Rondal also produced the deckhouse and main cockpit, with its integrated seating, as a single piece of prepreg composite superstructure measuring 17.5m by 7m, which when bonded to the hull contributes a significant amount of additional stiffness.

Another large composite structure built by Rondal is designed to serve several purposes on the foredeck. A secure, recessed stowage bay for Nilaya’s main guest tender when she is on passage in cruising mode, it converts into a spacious lounge area when the yacht is anchored, with a broad expanse of daybed cushions and seating around three sides of a table. With the tender and cushions removed and lids fitted, it becomes a part of the flush foredeck.

Among the other deck components that Rondal produced for Nilaya are the custom housing of the twin-steering pedestals, the lazarette, the crew companionway and the removable hardtop bimini that shelters and shades the passenger cockpit. Ten hydraulic deck winches – two on each side of the sailing cockpit, two on the aft deck and four clustered around the base of the mast – were also supplied, along with eight flush, custom skylight hatches in the foredeck and various pieces of titanium hardware.

Under the deck, Nilaya’s sail-handling hardware includes Rondal’s new design of lightweight, hydraulically operated captive reel winches, which combine an aluminium chassis with a filamentwound carbon fibre drum. Exceptionally powerful and proven to withstand very high loads, these winches weigh only half as much as the previous generation of captive reel winches. They are also available as electric-powered variants with innovative peak shaving technology that feeds power back into the yacht’s batteries. However, for a long-distance ocean cruising yacht like Nilaya that is expected to spend long periods of time in remote parts of the world, the relative simplicity of a more conventional hydraulicpowered winch setup has obvious advantages. Rondal’s line feeders work in step with the captive winches, providing continuous line tension to ensure a perfect tight coil around the drum.

Also under the deck – in this case the foredeck – are a couple of Rondal’s sail drums. These are designed to enable faster, easier and safer launching and retrieval of large downwind sails by a relatively small crew, in Nilaya’s case allowing big A-sails to be used more often on ocean voyages and also to be stowed securely when not in use.

Above: the cabin top for Nilaya breaks new ground for superyacht engineering, being both light in weight and contributing substantially to the yacht’s global stiffness.
Below: the yacht’s mast is stepped by Rondal staff at Huisfit

Rondal’s participation in this project also included a key role in the design and engineering loops for the yacht’s aero package, working closely with Reichel/Pugh and Doyle Sails. ‘Bringing in the mast and sail designers early in the process has significant advantages,’ naval architect Jim Pugh explains. 'From the aero CFD side, Rondal and Doyle shared high-quality data about sail forces and sail loads that we integrated into the hydro CFD studies of the candidate hulls. This markedly improved the quality of the CFD hull testing and the resultant performance prediction. The mast and sail loads were then input into the hull and deck’s structural engineering. These studies are applicable to any design whether Featherlight or heavy. No matter the thickness of the plate or weight of the composite, such a study will yield remarkable results.’

Royal Huisman’s Featherlight construction methodology is a holistic approach that encompasses the rig as well as the hull. One of Rondal’s major contributions to the weight-saving success of this project, working with Doyle and Reichel/ Pugh, was a new arrangement of running backstays that saves an impressive 1,200kg.

Nilaya is the first yacht in the 150ft size range that is designed specifically to take full advantage of the Structured Luff sail technology pioneered by Doyle Sails. This choice allowed the entire Rondal rig – including the Panamax mast and various other components – to be built significantly lighter, saving weight in places where it has the greatest impact on the yacht’s performance and motion in a seaway. For example, tapering the top of the mast on all four sides and eliminating the need for a headboard lock in favour of a hook to capture and hold the head of the mainsail saved 150kg at the masthead, which might not sound like a lot given the very large size of this yacht, but in that position it actually has a measurable positive impact on her centre of gravity.

The most obvious innovation on Nilaya’s mast is the curved shape of her spreaders. While it does look stylish, the purpose of this new design from Rondal is purely functional. It allows a slightly larger genoa that is fuller in the leech to have a tighter sheeting angle.

Towards the end of February, Nilaya’s completed rig was delivered to Royal Huisman’s facility in Amsterdam, where Rondal engineers supervised the stepping of the mast. Back at headquarters in Vollenhove, the design office was already preparing for an even larger project – one that requires Rondal yet again to enlarge its composite mast construction and curing facility. An order has been received to build the mast for a yacht that is set to be the world’s largest sloop, once again due to be built by Royal Huisman: the 85-metre (280ft) Project 410. And it’s only a matter of time before another client turns up with even higher ambitions.

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Nilaya’s innovative Featherlight construction technique is designed to be lightweight, stiff and very competitive in regattas, without compromising the comfort and low noise levels associated with Royal Huisman yachts

The bar was set extremely high for the 47-metre (154ft) Nilaya, Royal Huisman’s most recent yacht, which has just been Christened at Het Scheepvaart museum (the National Maritime Museum) in Amsterdam. The last yacht to bear that name was a 34-metre (112ft) full carbon sloop that combined a very high level of performance with ocean cruising capability, striking good looks and a luxurious interior. A game-changer on the superyacht racing circuit, in the 13 years since her launch that boat has won almost every race she entered… and she has done a lot of racing.

While many aluminum vessels have some composite parts, Nilaya is much more a hybrid

It’s not surprising, then, that the new Nilaya has a fair amount in common with her namesake in terms of general concept, proportions and aesthetics. She is drawn by the same design team of Reichel/Pugh and Nauta, even more elegant and built on a substantially larger scale, with no compromise made in her racing ambition. However, the design brief also put a greater focus on long-distance ocean cruising, with more emphasis on considerations such as impact resistance and ease of repair in remote parts of the world. Thus, despite some similarities – profile, straight bow, wide transom, twin rudders and so on – the new Nilaya is actually a significantly different beast.

Royal Huisman’s Featherlight is an integrated, multi-disciplinary approach focusing on weight reduction through advanced construction technology as employed by the European Space Agency

One key difference is the hull. Rather than carbon, it’s mostly aluminium. But this isn’t the sort of aluminium that’s typically used in large yacht construction, it’s Alustar – a premium grade alloy with 20 per cent more tensile strength. And this is, strictly speaking, a hybrid build with a lot more carbon components and structures than one would expect to find in an aluminium cruiser-racer, even one that is focused on high performance. Royal Huisman’s sister company Rondal is of course a world leader in marine carbon fibre fabrication and the Nilaya project benefits from the inherent synergy between them. Why not build the whole yacht in carbon? ‘The owners wanted a powerful performer with easy-to-helm responsiveness, basically all the good habits of their last boat but with more comfort and less noise,’ says Nigel Ingram of MCM Newport, the owners’ representative for the build. ‘Alustar is the right material for an advanced, top quality superyacht for global cruising. It deals with noise better [than carbon] and is a better choice for cruising in comfort to remote locations. However, we also thought it was possible to build a lighter aluminum highperformance superyacht. Royal Huisman was not afraid to invest in research to explore and develop all manner of innovative weight-saving possibilities. They really chased the details.’

The variable spacing of frames in Nilaya’s hull was calculated and optimised with in-houe FEA software

The design process in detail

The Nilaya project began with a general concept developed by Nauta Design, which set the key parameters for the shipyard, the naval architects and the other key players involved. ‘We asked ourselves a very simple question,’ Nauta’s co-founder Mario Pedol explains. ‘Could we design an aluminum yacht that was much closer in terms of displacement to an equivalent carbon boat? The answer was yes, following my intuition that hull and deck are only 15 per cent of the total weight of a modern sailing yacht. This was backed by analysis of our most relevant projects from our designs.’

‘In this process we took into account the owners’ priorities including less noise, the strength of the material and the possibility of repairs around the world. We set about discovering ways to minimise the difference [between aluminium and carbon] and to look for advantages elsewhere. Royal Huisman supported this vision with enthusiasm and accepted the challenge.’ After the concept came the detailed naval architecture with Reichel/Pugh working alongside one of the world’s leading CFD consulting teams, Caponnetto Hueber. Giorgio Provinciali who brought about 20 years’ worth of America’s Cup experience to the project. Top performing designs in both aluminium and carbon were made into models for tank testing.

Beyond conventional CFD analysis, the design team also conducted a sophisticated RANS code analysis – a method more commonly used to optimise the shape of submarine hulls – to predict underwater turbulence generated by the hull, keel, rudders and propellers. They then collected extensive wave data from the owners’ favourite windy cruising grounds and developed new hull shapes to run through the RANS CFD code to improve the seakeeping and motion characteristics of the yacht under sail and power.

Meanwhile, the design loop for the aero package was also under way with Reichel/ Pugh working alongside Doyle Sails and Rondal, who designed and built the yacht’s integrated sailing systems as well as her spars. ‘Bringing in the mast and sail designers early in the process has significant advantages,’ Jim Pugh says. ‘From the aero CFD side, Rondal and the sail designers shared high-quality data about sail forces and sail loads that we integrated into the hydro CFD studies of the candidate hulls. This markedly improved the quality of the CFD hull testing and the resultant performance prediction. The mast and sail loads were then input into the hull and deck’s structural engineering.’

Nilaya’s VPP promises a level of performance that will challenge the leading yachts on the superyacht racing circuit, with boatspeed exceeding the true wind speed on a close reach in a 10-knot breeze under mainsail and jib alone.

Royal Huisman’s in-house 3D engineering and weight management is comprehensive and extends to lighting, insulation, and all mechanical systems

Throughout the year-long design process the overall plan for the yacht hardly changed, John Reichel says, except that the hull became one metre longer with the extra length distributed mostly at the ends. ‘Weight distribution is critical for assuring comfortable motion on a cruising yacht,’ he explains. ‘We gave the shipyard team a weight study early on, not just for the total but for balance and maintaining the proper centre of gravity. Royal Huisman responded with extensive Excel sheets showing the weight of every element. That’s a process typical of the highest-end racing programme construction.’

The deck plan was also developed with great attention to detail, ensuring that the layout works equally well for both cruising and racing. Royal Huisman built a 1:1 mock-up of the entire aft half of the yacht to fine-tune all the aspects of this dualpurpose functionality from sail controls and steering pedestals to the dining table, the seatback angles of the sun loungers and the steps from the sail-handling cockpit to the lounge area on the aft deck, leading to the bathing platform. Sightlines over the coachroof from the helm positions received critical attention and the fullscale mock-up was tilted to simulate typical heeling angles under sail in a range of conditions.

Nilaya is the first yacht built according to Royal Huisman’s new Featherlight method, which aims to narrow the gap in stiffness, displacement and thus performance between aluminium and carbon yachts. Described by the shipyard as a holistic process rather than a specific set of building techniques – ‘not a single process or construction material, but an integrated, multi-disciplinary approach focusing on weight reduction through advanced construction technology’ – Featherlight puts a strong emphasis on finite element analysis (FEA) and parametric modelling to achieve a wide range of gains in structural engineering. ‘Royal Huisman used FEA of Nilaya’s 3D model to fine-tune the engineering to a much higher level, adjusting plate thickness in the computer and predicting longitudinal stiffness or deflection,’ naval architect Jim Pugh explains.

Royal Huisman has made a major R&D investment in its Featherlight technology, which the shipyard regards as an important step in the evolution of its own DNA. It has developed its own in-house software tools for parametric modelling, which enables its design office to determine precisely the right thickness of any construction material for any location to achieve the design parameters. This empowers them to make smart decisions regarding, for example, the relative merits of aluminium and carbon in any structural application. It also allows them to design and optimise composite structures and components, in which carbon and aluminium are bonded together. Featherlight construction can also involve gluing aluminium components to each other rather than using fasteners.

The last time Nilaya appeared in Seahorse (February 2022 issue), halfway through her build, she was known only by the enigmatic code name Project 405 and already her ambitious weight saving targets were generating a fair amount of interest. Now completed and launched, those targets have been fully achieved and her displacement is 11 per cent lower than a yacht built to the same design by the usual methods. How was that achieved? Like a racing yacht build, continuous weight monitoring is a crucial part of the Featherlight process with a dedicated weight engineer assigned to the project from start to finish. Reichel/Pugh and Nauta Design worked with Royal Huisman on a daily basis throughout the design and build, jointly overseeing the weight study.

An overall weight target was agreed and every aspect of the build was given its own weight budget. With integrated teams exploring all the elements of the boat concurrently, everyone was aware of how each decision impacted others. Suggestions for improvements were shared and analysed in real time. For example, by a taking critical look at the high-voltage air conditioning (HVAC) system and selecting direct expansion and fan coils for each room, the total weight of the yacht’s hotel systems was reduced by 600kg. Rondal, meanwhile, managed to reduce the weight of the sailing systems significantly (see pages 82-83).

The completed yacht was transported from Royal Huisman’s HQ at Vollenhove to its Amsterdam facility for launch and seatrials

Conventional materials for reducing noise and vibration, such as foam panels lined with lead, add a lot of unwanted weight. To stay within Nilaya's interior weight budget, Royal Huisman made extensive sound attenuation studies and developed sophisticated composite panels using cork, foam, honeycomb and other materials. The owners were offered three options for the yacht’s interior cabinetry with different levels of weight, sound insulation and finish.

Nilaya’s high-modulus carbon Rondal mast was stepped in Amsterdam

Royal Huisman also developed a “tribrid” propulsion system that provides three ways of powering the variable-pitch propeller and offers emergency ‘get home’ propulsion without the need for a separate third engine and gearbox. That alone saved two tons. Every incremental reduction in the yacht’s displacement in turn reduces the amount of power required for motoring, so the engine itself can be lighter and the engine room smaller, leaving more space for accommodation inside the hull.

‘I am proud of the investment we have made in advanced engineering and of the way teams from Royal Huisman and Rondal advanced new solutions to meet the brief from very knowledgeable clients and designers,’ Royal Huisman’s chief executive Jan Timmerman says.

‘Nilaya's owners also deserve congratulations for pushing everyone to achieve just a little bit more and for encouraging innovation at every step. Nilaya will be the world’s lightest aluminum sailing superyacht for her length; she rewrites the script for highperformance superyachts.’

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From fast charging systems and photovoltaic glass to the next generation of hydrogen fuel cell technology, McConaghy Boats is pushing the boundaries of sustainable marine power solutions

On the face of it, sailboats provide a head start when it comes to going green. And yet despite the number of ways in which hydro and wind generated power has already been achieved across both racing and cruising craft of all sizes for many years, stepping things up to the next stage of emission free systems is proving to be more taxing than many had originally anticipated. McConaghy Boats are further down the line in this area than many.

All McConaghy catamarans have a huge amount of horizontal surface area where solar panels can be mounted

They see the road to success as involving a number of stages that are based around combining a range of techniques rather than holding out for a single solution. The company also has several clear advantages both in the type of boats that they are famous for and their acknowledged experience with highperformance composites. In particular, McConaghy’s range of luxury performance cruising cats has not only grown considerably over the years, but has drawn a great deal of attention thanks to their looks and performance.

So, when it comes to generating green power, cats of the type that McConaghy build start with two key strengths, performance is the first.

Speed is clearly important when considering hydro-generation and the McConaghy range is well known for its impressive performance. Building lightweight boats is key and here McConaghy’s long-held expertise in building advanced carbon structures places them well ahead.

‘Building light is the starting point because when it comes to propulsion systems it means you need less horsepower to start with, which in turn means less wastage and of course more performance,’ says McConaghy Boats’ CEO Mark Evans.

The second significant advantage of a cat is size. By their very nature, cats have plenty of surface area for installing solar panels when compared with an equivalent length monohull. So it’s little surprise that across the McConaghy range of seven sailing cats from the MC55 to the MC115 solar power generation has proved popular.

‘We buy the best solar solutions that are available and basically we cover the yacht and most of the horizontal surfaces with the solar panels,’ Evans continues. ‘When it comes to research on what’s available on the solar panel market and how it performs, we’ve done a great deal of work in this area to the point that we consider ourselves to be experts in this field. There’s a wide range of solar products out there and identifying the right panels for the job is not always that straightforward. Some of them are more efficient than others due to heat transfer and then there’s the issue of ensuring that their specific application means that they don’t overheat and so on. But, 90 per cent of the boats that we produce are now fully covered with solar panels. To include solar panels has now become the norm which is certainly a step forward.’

But for McConaghy the work doesn’t stop here when it comes to additional ways in which power can be generated. Instead, the company has taken the quest for green power further by considering and employing a range of innovative and advanced techniques as well as a major step forward that could prove to be a complete game changer.

‘Everybody's pushing us for green solutions,’ says Evans. ‘One of the ways that has been popular so far is to use Integrel systems, which are fast charging 48 volt systems that can generate up to six kilowatts per engine. This means that when you're motoring you can push 12kW back into the batteries, way more than what most boats achieve. The system is basically like a big alternator hanging off the side of the engine.

Below: An Integrel 48-volt fast charging system can put an impressive 12kW back into the batteries via a pair of alternators when the boat is motoring

‘Using the main engines like this means that you're not wasting the power but you're generating electricity and putting it back into the system. Around 50 per cent of our clients are now taking this fast charging system. It also means you can make savings when it comes to the main generator which can be smaller and cater for just the house loads. Then, when you need to ramp things up you've got two other generators with the main engines. So, even just at this level, with the presence of solar power you do have a lot of means of putting power back into the boat.’

McConaghy is also using an increasing amount of solar photovoltaic (PV) glass aboard their boats which allow the windows to act as solar panels too. ‘The glass that we buy for skylights and windows has a built-in solar membrane. You can still see through the glass, but with this technology the glass now becomes a solar panel as well. I would say around a 50 per cent of our clients are taking the solar glass option,’ he continues. ‘You can get different levels of efficiency and while this glass is a lot less efficient than solar panels, when you add this into the overall equation you can start to see a path towards a fully green yacht.’

But despite this significant progress, the company is working on a bigger project that Evans says could be a game changer. The system is currently in development and he’s reluctant to give away too many details at this stage, but when pressed he confirmed that the basis of the next generation of power supply is around hydrogen fuel cells.

Those that have followed McConaghy’s recent projects around the America’s Cup world may not be surprised to hear this given that the company was so closely involved with Emirates Team New Zealand’s hydrogen-powered foiling chase boat. From an emissions point of view the benefits of hydrogen fuel cells are well known, namely that water is the only waste product. From a technical point of view, hydrogen fuel cells are far more efficient than straightforward electrical batteries that, by comparison, have far less energy density making them a much heavier solution for the same amount of power.

‘From many points of view, especially when it comes to emissions, hydrogen fuel cells offer big benefits. But there are also a number of key issues that make this technology hard to apply when it comes to blue water cruising boats,’ he says.

‘One issue is the need to store hydrogen at high pressure, around 350-720bar which means some highly sophisticated and expensive engineering. But from our experience it’s also not that appealing to our cruising clients. Another issue is that of availability. While hydrogen is used widely in industry and available in developed parts of the world, it’s very difficult if not impossible to get it in less populated areas. But we believe there is a way of achieving an efficient hydrogen fuel cell that overcomes these issues that will really open up the possibilities.’

So how far away are we talking?
‘To get to the point of being able to prove the concept I’d say around another six months,’ he says. ‘The fact is that while this will represent a big step forward, the technology is already out there and well proven in other fields. What we are doing is showing that it can be applied on a different, smaller scale and all our work makes us believe firmly that it can be.

‘As we’ve shown with our work with integrated systems and solar panels we believe that the route forwards is via incremental change. As a result, in this case it may well be that to start with, the main propulsion system remains as a diesel, but the goal with this new technology would be to phase this out eventually. And once we’ve proved the concept, I’m pretty sure that will happen quickly because unlike the high-pressure hydrogen route, our system will allow us to store hydrogen at much lower pressures which in turn makes the entire system more manageable and scalable.

McConaghy cruising cats are renowned for their distinctive styling as well as their excellent performance under sail

‘Having said that, because of the weight of the system there will likely be some practical restrictions on just how small you can go, but for our range of boats I see few issues here. Overall, the work we’ve done shows that there is no reason why we shouldn’t be powering the entire boat with this new technology and that is really exciting.’

Meanwhile, and aside from the leadingedge developments when it comes to power generation, McConaghy’s core business still revolves around creating high-quality performance boats.

‘Whatever the final choice when it comes to power, we're still creating an advanced platform for our customers to create a custom-built boat where owners can change the layout, specify individual finishes and create the unique boat that they’re after. We work very, very closely with them on every single detail.

‘Yet among all this choice and the wide variety of layouts and styles that emerge when boats hit the water, when it comes to the future of power and the need to go green, the overwhelming majority of our clients are on the same page and moving in the same direction.’

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