“Build me a beast. Don’t build me a sheep in wolf’s clothing”. Nothing to say, the owner of the 58m/190ft high-performance sloop Royal Huisman Ngoni was clear about his intentions.
The reverse sheer
“The owner wanted me to take a fresh look at large yacht design“, declares the designer Ed Dubois. “He wanted me to go back to my roots in the late 1970s and ‘80s when we were designing race boats, but he also knew we had designed a number of high performance yachts that were nevertheless seaworthy and comfortable cruisers. So I had to reset my internal computer, if you like, and look hard at how we could save weight and add strength. That’s how the reverse sheer came about“.
Designed by Dubois Naval Architects and featuring an innovative interior by Rick Baker Ltd, Ngoni is luxurious as well as ‘fast and furious’
The reverse sheer that visually defines Ngoni began as an exercise in creative expression but it soon became apparent that it also held the vital key to the hull’s structural stiffness, delivering 12% more strength and load resistance than conventional sheer using the same materials.
The importance of this factor to the entire project cannot be over-stated, given the challenge of constructing a strong, slender hull with numerous openings, yet rigid enough to take the heavy loads of a huge sloop rig (for example, up to 60 tonnes on the forestay alone).
“Think of a sloop as a bow and arrow: the bow is the hull, the arrow is the mast and the string is the forestay and backstay“, continues Dubois. “You can imagine that tension creates an awful lot of bending moment, which is fine if you can compensate with a strong, deep beam in the structural sense, but the Beast has a relatively low freeboard and shallow beam with no structural superstructure.“
“Then you make the situation worse by making holes in the deck for tender bays, sail lockers and hatches – metal that would usually resist the compression in the deck. You can overcome that by adding a substantial sheer strake and Ngoni has a top plate of solid 35mm aluminium that acts like a ring beam around the hull, but it’s still a struggle to come up with the required stiffness.“
“So then I started thinking about a reverse sheer, which is much like the structure of a bridge where the road is convex to resist the compression created by the weight of the traffic. We ran it through our structural analysis program and suddenly we had a 12 per cent increase in stiffness for the same weight. It’s something you sometimes see on high performance boats like Samurai, but this is the first time I’ve designed a sailing yacht with a reverse sheer.“
The teak foredeck shelters giant flush hatches with continuous, uninterrupted planking to conceal a large tender, a crane, spa pool, sail locker and cooled waste locker. Just forward of the forestay, the guardrails plunge to deck level, obviating the clutter of a pulpit.
Aft of the foredeck, the towering carbon mast is one of the world’s three largest one-piece spars ever built, all three having been manufactured by Rondal. Ngoni’s full air-draft is 75m / 247ft and therefore disregarding the so called ‘Panamax’ level.
The outer shell of the performance boom is custom-styled in harmony with the overall aesthetics of the hull while, operationally, the mechanics of the system provide fully flexible mainsail foot and leach tensioning at both full hoist and in all reefed positions.
Sail management is provided by Harken winches and deck hardware, complemented by Rondal reel winches with electrically-driven variable speed feeders. These feeders have been developed for high speed operation, contributing to overall safety and reliability.
All deck hardware is bead-blasted to a uniform titanium look, one of many examples of ‘attention to detail, in every detail’ aboard Ngoni.
“The owner wanted a yacht that was fast and punchy without losing the concept of a world cruising boat, which allowed me to think outside the box and defy convention“, declared Ed Dubois. “I remember when he initially came to the office I sketched out a design and he said, ‘It’s OK, but a bit ordinary. What are you going to do now?’ I went away and came up with the reverse sheer, but was worried he might not like it. The next time we met in London I showed him the design and he loved it – in fact he gave me a big bear hug! Actually, Ngoni has a convex sheer at the maximum bending moment amidships that transforms into a concave sheer aft, which looks more attractive and provides better visibility from the cockpit“.
The 853m2/9,182ft2 square-top mainsail is notable not just for its load-reducing halyard lock but for the innovation allowing the square-top and its supporting diagonal batten to detach automatically and furl neatly into the styled performance boom with minimal intervention from the crew.
To further reduce weight and drag, the team opted for continuous carbon shrouds from deck to masthead and internal D-Tang connections where diagonal stays meet the mast tube – thus also removing the visual clutter of turnbuckles.
The development of the rig was a major project in its own right and its success is a tribute to the highly productive collaboration between spar builder Rondal (Royal Huisman’s sister company), sailmaker North Sails and Carbo-Link, together with Dubois Naval Architects and the shipyard team.
Rondal’s 24 m / 79 ft style-to-order performance furling boom with automatic detaching and attaching top of square-head mainsail and gaff batten.
The interior design
The owner’s core brief to the Rick Baker design team was simple in the extreme, yet offered a clear direction of travel, with plenty of room for creative interpretation: “Don’t design a traditional yacht interior”.
“The yacht is a total one off, with a unique design by Ed Dubois“, said Rick Baker, “and the interiors had to reflect the same state of the art design. So we have consciously avoided giving the yacht a theme, but rather chose to make the different areas very individual. It was important to us to not let the craft feel like a hotel, and to avoid repetition in the cabins etc.“
A few steps descend from deck level to the guest cockpit, an intimate and sheltered outdoor space for reading and relaxation. The deck house overhang, together with electrically-powered retractable windbreakers, ensures a comfortable environment in all conditions.
To starboard there is a bar and dining area while, to port, there is informal seating with coffee tables and, when required, a pop-up television. Going forward, doors give access to the nav station and stairs leading below to the crew area and machinery spaces. The head of the retractable keel housing is located between these stairways yet, thanks to meticulous design, its presence goes un-noticed.
Owners’ and guest accommodation is accessed via a curving staircase from the deck house to the guest lobby area. There is a twin guest cabin with spacious bathroom to port and a double guest cabin featuring a Japanese bath to starboard. Both feature high quality exotic veneers, marbles and resin finishes.
The owners’ suite, aft, comprises a full-beam stateroom with bespoke built-in furniture, twin doors to an enormous bathroom, a spacious study with its own bathroom and a large gym with an opening hull port in the topsides.
The sophisticated audio-visual system of Ngoni was thoroughly tested a full year prior to delivery. The owner was very specific about the configuration, asking iPad users to interface with the custom setup supplied by Tijssen Elektro based on Royal Huisman engineering. With 48 terabyte storage by Kaleidescape and a vault for 320 disks, there is access to a wealth of music and movies.