The design process in detail The variable spacing of frames in Nilaya’s hull was calculated and optimised with in-houe FEA software
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 thematerial and the possibility of repairs around the world.We set about discovering ways tominimise the difference [between aluminiumand carbon] and to look for advantages elsewhere. Royal Huisman supported this vision with enthusiasmand 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. 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
Royal Huisman’s in-house 3D engineering and weight management is comprehensive and extends to lighting, insulation, and all mechanical systems
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 dual- purpose 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 full- scale mock-up was tilted to simulate typical heeling angles under sail in a range of conditions.
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