Oi60: The futuristic trimaran design redefining luxury sailing

The Oi60 is a design study for a 63.5-metre sailing trimaran by James Carley of JC Yacht Architecture and Rob Doyle Design. The avantgarde concept builds on the positive reception of another multihull project, the smaller Domus concept with Van Geest Design that we reviewed in the very first issue of How to Build It.

Oi60 yacht concept by Rob Doyle Design & byJC

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“I‘ve been sailing much of my life and was intrigued by the whole idea of a world explorer trimaran and being able to cover a lot of ground quickly in a luxurious but sustainable way,” begins James Carley, a naval architect and chartered engineer who honed his design skills at the studios of Martin Francis and Bannenberg & Rowell. 

Carley’s bold exterior design and interior layout for the Oi60 are strikingly, but the basic principles behind the trimaran configuration remain the same. Trimarans are usually wider than catamarans, which means more interior volume and deck space; maximum heel angles of two degrees allow the windward hull to come out of the water for less drag, higher performance and more comfort under way; three hulls in the water are also more stable at anchor with vastly reduced motions compared to a monohull; and unlike a catamaran, all the systems and engineering can be centralised in the main hull, which means fewer structural stresses and deflections – all factors that might persuade owners to switch from power to sail.

Oi60 yacht concept by Rob Doyle Design & byJC

The armas or outriggers are effectively for buoyancy purposes only and while they can be used for tankage and storage, all the guest accommodation and interior living spaces are concentrated on one level on main deck with the crew quarters and services on the lower deck in the central hull. This makes for a more inclusive onboard experience and vastly improves circulation flow for both guests and crew by avoiding the inconvenience of multiple decks – evident in Carley’s innovative ‘radial’ layout. It also brings cost savings by simplifying the systems design and construction.

“Sailing yachts can cost twice as much to build per gross ton as motoryachts,” Rob Doyle points out. “We approached this project by pricing it as if it were a conventional motoryacht with two rigs, but designing outwards instead of upwards. We’ve calculated the volume at over 1200GT, which is equivalent to a 65 or 70-metre monohull, but you get the huge open and semi-open deck spaces that only a trimaran can offer for free, so to speak.” 

Oi60 yacht concept by Rob Doyle Design & byJC

It is no coincidence that the ‘Oi’ in the concept name stands for ‘Outside-inside’. Like Domus, the crossbeam connecting the three aluminium hulls is, in effect, a huge perforated box that offers excellent strength and rigidity. The perforations or cut-outs have been designed around the choice of build material, load paths, boundary conditions and other constraints to offer enormous semi-open areas as well as giant windows, especially in the forward-facing suites. The result is something that could easily double as the villain’s futuristic lair in a James Bond movie.

“On the bigger motoryachts with four or five decks, everyone tends to congregate on one particular deck anyway, so why not have it all on one multi-purpose level?” asks Carley. “We can still carve more intimate spaces out of that much bigger space to suit different needs throughout the day. And a lovely change is that we’ve been careful not to be greedy by trying to fill up every square of interior, hence the semi-open areas.”

Moonraker

Critical to the whole concept is a feature that is still under wraps. Like Domus, the masts will be Panamax but unlike the earlier concept that had a hoist-able, double-luffed mainsail to achieve some of the efficiency of a wing sail, Rob Doyle Design has devised a new self-supporting, joystick-controlled square rig called the Moonraker (named not after the Bond novel, but the topmost sail on the fastest square riggers of old). Rob Doyle Design claims the Moonraker offers superior performance at less cost and refer to as the Dynarig’s ‘Nokia moment’.

Oi60 yacht concept by Rob Doyle Design & byJC

“We’ve signed an NDA with Southern Spars who are undertaking a research program to verify performance and the Moonraker will be officially presented later this year,” says Mark Small. “We’ve been sitting on the Dynarig concept for years, but never got to version two-point-oh and without giving away too much, the critical point about the Moonraker is what the Dynarig can’t do. We hope to achieve downwind performance similar to a spinnakered ketch, which will make passagemaking much quicker. And critically, it will be cheaper to build than an equivalent Dynarig, so basically win-win.“

Maltese Falcon and Black Pearl, currently the only yachts launched with Dynarigs, have full-carbon masts and spars. This would not necessarily be the case on the Oi60 and the masts could be of aluminium, since the trimaran has so much righting moment anyway there is less need for a superlight but super expensive high-modulus rig.  

Team Trimaran

James studied naval architecture at the same time as Rob and Mark at Southampton University and the opportunity to collaborate came when he left Bannenberg & Rowell to set up his own design studio. The immediate inspiration for the Oi60 was a YouTube video he saw of a group of freewheeling friends sailing a performance catamaran from Tahiti to Hawaii. James got to thinking how to make long-distance sailing even faster and was initially keen to add foils to boost speed and comfort still further, but was dissuaded by Rob and Mark.

“At this size the structures involved would be enormous and if you have a problem with them, you have a very big problem,” says Rob. “We figured it was also unnecessary, because we have loads of performance already at hand and the idea is to make the Oi60 as cost-effective to build as possible. Why would you open the door for that kind of added complexity and cost?”

Oi60 yacht concept by Rob Doyle Design & byJC

Given the huge surfaces area the trimaran configuration offers, it makes sense to cover it with solar panels to generate renewable energy. Rob Doyle Design reckons that 300 kilowatt-hour per day could be produced from some 300-square-metres of photovoltaic cells to reduce generator loads for hotel use. Moreover, when sailing the freewheeling propellers can regenerate energy to store in batteries for future use. At hull speed the extra drag makes little difference, but the prop blades can also be folded when performance under sail is a priority. 

“We’ve calculated that when sailing, the solar cells and regenerative propellers can produce all the energy that's required on board, including HVAC, which will be way in excess of what's actually needed to run the vessel,” says Mark. “It’s a pragmatic combination of renewable and regenerative for what will be a diesel-electric or hybrid diesel-electric boat.” 

Under the Influence

Although prospective clients have expressed interest in the Oi60 concept, its designers purposely avoided undue influence from owners while developing the concept.

“Most owners have preconceived ideas of other boats in their heads,” says Rob. “We wanted to nip that in the bud so we could come up with something new and fresh. James came to us over a year ago with a blank piece of paper and we took our time developing his ideas into something very unique. Sometimes you have to give these creative projects time to develop, so we didn’t rush it or try to mash three or four other boat designs together.”

As naval architects as well as designers, all three are well aware of the technical and financial constraints associated with designing superyachts. After all, if the aim is to provide owners and shipyards with solutions that are both new and viable, there is little point in coming up with ideas that are ultimately unbuildable.

Oi60 yacht concept by Rob Doyle Design & byJC

“We see a lot of concept projects that can't be built, or they can be built but would cost half a billion to manufacture,” Mark points out. “We always balance the creative with the technical, which also means taking into account factors that may affect the price. We would never have started with the Oi60 unless we thought it made sense.”

“I would really love to see it get built,” ends James. “Done right, I think it could be very special.”