Super sloop creators think big

By ROBIN BAILEY

She's big but perfectly formed, and on her big day out she certainly turned a lot of heads.

Capable of hoisting 2200 sq m of downwind sail from her 63m mast, super sloop Tiara made an impressive sight on her maiden sail on the Waitemata Harbour. The mast is the largest designed and manufactured by Auckland-based Southern Spars.

At 54m, Tiara, built at Henderson by Alloy Yachts, is the largest super yacht to be built in New Zealand.

The carbon-fibre mast displays design and engineering as elegant as Tiara herself, the strength and utilitarian purpose masked by the designers' flair.

Glenn Simpson, Southern Spars project manager, has lived with Tiara's mast since 2000. Not a day has passed when he has not thought about it. And for 18 months of his life he worked full-time on it.

It started the way every project does, with a design brief, a sail plan and some ideas. The only difference, says Simpson, was that it was big - very big.

Everything about this mast is impressive. With furlers and foils it weighed in at 15 tonnes as it was stepped, and that includes the seven tonnes of carbon fibre that went into its manufacture.

The mast's section is 900mm by 350mm. The furling mainsail requires a further 400mm ramp on the after-edge to accommodate the furling mainsail. The boom is 21m long and at its deepest point 1300mm. It weighs 2.5 tonnes.

The rig has to be immensely strong to cope with heavy-duty loads: stainless steel rod in the vertical standing rigging is 57mm in diameter with a breaking load of 290 tonnes; the diagonal stays are 45mm stainless rod with designed load of 195 tonnes. More than 30,000 hours of work went into its construction - design, project management, building moulds for the mast, spreaders and boom, laying up the fibre, lamination, curing, fairing and painting.

On a project of this size, designers start from scratch. Each yacht has its unique design criteria and very few off-the-shelf fittings can be used. Most are designed and made in-house at Southern Spars.

For Tiara, masthead gear including electronics had to be able to fold so that the mast could safely navigate the 62m clearance of the Bridge of the Americas on the Panama Canal.

Simpson and the team solved that one, giving Tiara an additional 2.5m of clearance when negotiating the canal. But just in case, before Tiara passes under the bridge for the first time the skipper will check the clearance.

Having a helicopter pad on the after-deck demanded devising a method of moving the backstay and boom out of the way. Southern Spars' designers and engineers have developed a system that has yet to be tried, but they are confident it will work without a hitch.

The design brief called for a crow's nest that could travel up and down the rig, to a height of 30m. When not in use, it is at deck level. It works much like an elevator, operated from the controls on the instrument bracket or by a wireless handheld instrument from the nest itself.

Safety is paramount. Southern Spars undertook a full testing programme of the locking system.

The crow's nest also meant that Simpson had to find a new way to mount the radar brackets on the mast, which are usually on the front of the mast where the track for the crow's nest is located. The innovative idea was to attach carbon- fibre arms under spreader one to support the radars.

The Southern Spars designers came up with a robust and unobtrusive crow's nest with a view that can only be bettered from the top of the mast in a bosun's chair.

North Sails provide the power that will drive this 435-tonne super yacht at speed in supreme comfort and style on the world's oceans.

* By comparison, an America's Cup yacht is 24m long, the mast is about 32m high, and the downwind sail area is about 480 sq m. They weigh about 25 tonnes.