Ali Wood finds out more about visionary proa boat designer, Rob Denney

New Zealand designer Rob Denney is a proa boat enthusiast.

He built his first catamaran aged 14 and, after skipping his accountancy exams to do the Sydney-Hobart race, never looked back.

He’s spent his career racing, delivering and designing yachts, among them a catamaran he capsized in a ‘gung-ho’ two-handed round-Britain attempt (the boat, considered a shipping hazard, was destroyed by the Irish Navy) and a 30ft Iroquois catamaran propelled by a three-bladed windmill.

“That taught me a lot about engineering,” says Rob. “We sailed at 6 knots into 20 knots of wind, which I considered a success. It was fun!”

A catamaran being powered by. windmill

Denney’s early windmill design powered an Iroquois catamaran. Credit: Rob Denney

Rob returned to Australia and launched a business selling cedar-strip kit boats, before building his first proa boat in 1995 using stitch and glue ply, an alloy mast and a ‘bewildering variety’ of steering combinations.

At 16ft (5m), his proa was competitive with Lasers and slow beach cats, and taught him a lot about sailing proas.

He continued to experiment with different ideas, changing rigs, beam arrangements, steering and hull size.

“Proas range in size from small boats ballasted by baby coconuts to ocean crossing vessels capable of carrying a dozen people and supplies for many weeks,” he says.

“They were probably the first improvement made to a floating log by early sailors. A second, smaller log was lashed to a cross beam to stop the main log capsizing. Rigs were added later when technology allowed.”

Racing proas

The first racing proa to gain celebrity was 40ft (12m) Cheers, which came third in the 1968 Singlehanded Transatlantic Race (OSTAR).

The rig, rudders and accommodation were all in the windward hull but she was notoriously difficult to shunt.

Her success triggered a spate of French-built single-handed proas, but after numerous capsizes and non-finishes they were banned from short-handed races in Europe.

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In 1975, 60ft (18m) Crossbow broke the 30 knot barrier with a speed of 31.1 knots in Weymouth, but she could only be sailed in one direction and towed back.

Her owner, Sir Timothy Colman of the mustard dynasty, held the World Speed Sailing Record for many years with his Crossbow proa designs.

Remarkably, the current record now stands at 65.45 knots, set by Paul Larsen in Namibia in 2012, aboard the proa Vestas Sailrocket 2.

Rob has also designed a racing foiling proa for the Volvo Round the World Race in-port series.

What makes proas unique?

The difference between proas and ‘regular’ multihulls is that the rig is mounted in or on a hull.

The steering (ie. rudder, paddle, oars or crew movement) and leeway prevention (ie leeboard, daggerboard, oversize rudder) are also on one hull; often the same as the rig.

They ‘shunt’ instead of tacking or gybing, so the windward hull is always to windward.

“There are many variations with proa designs, suggesting the ultimate proa is still to be built,” says Rob.

 Denney’s Orbiter 80 can be set up in a number of configurations, including as a medical services vessel. Credit: Rob Denney

Denney’s Orbiter 80 can be set up in a number of configurations, including as a medical services vessel. Credit: Rob Denney

Notwithstanding, he’s had a pretty good crack at it himself.

His prototype Harry was a 39ft (12m) proa, which he could shunt single-handed in 8 seconds.

He followed this with Harrigami, a folding trailerable proa, and then, together with designer Mark Stevens, drew plans for Visionarry, a 15m (49ft) version of Harry built for the Dutch market to take blind people sailing.

“These boats were all strip planked timber and had very curvaceous shapes,” he says. “They required a huge amount of filling, sanding and fairing.”

Modern methods

In 2005, Denney co-hosted a workshop with Derek Kelsall, something he recalls as a ‘real eye-opener’ about the use of foam infused on a flat table.

“I built a couple of hulls using this method and further developed it to use cheap flat panel moulds which cut the work required and the weight of secondary laminating for joins and fit-out.”

One of his first clients was Norwegian artist Steinar Alvestad, who now redraws all the boats using the new methods.

It’s a partnership Rob says works well.

“I send my designs to him in Norway, he draws the plans and makes them look pretty. I have trouble finishing things, but he’s a perfectionist. He fills in all the holes.”

Rob has nine current designs on his website ranging from the E25 made for trailering (with optional cockpit) to the EX40 weekender (with scope for longer cruises) and the Orbiter 80 cargo ferry.

 E25 is designed to be quick, clean, easy and cheap to build. Credit: Rob Denney

E25 is designed to be quick, clean, easy and cheap to build. Credit: Rob Denney

All are designed to be lightweight, low-cost and easy to sail.

“The Harryproas are designed to be the most possible boat for the least money, the easiest to sail and the safest,” says Rob.

“Capsizing my boat in the round-Britain focused my attention on safety. I spent 11 hours in a liferaft, so I’ve done everything to make them safe. They are very low-stress to sail, no foredeck work (no foredeck!). The masts are unstayed with self vanging wishbone booms, so the whole rig is an aerofoil without requiring any sheet tension to tighten the leech.”

He explains that cats and tris carry around a lot of extra boat solely so that, on the other tack, they will work.

They see loads from both directions so have to be built to withstand these.

Eliminating all the ‘extra bits of boat’ results in substantial weight loss and means the proa can have a far smaller rig for a given power to weight ratio, further reducing the loads.

Marshall Islands trial

Two years ago Rob took his proa design skills to the Marshall Islands in the Pacific, where he taught locals to build plywood cargo proas.

Sailing skills were dying out so his intention was to reintroduce sailing as a means of catching fish and carrying cargo.

“The islanders had outboards at the time but no-one had shown them how to look after them,” he said.

“There were no spares and petrol was expensive. They ran them till they died then couldn’t do anything.”

A proa boat being sailed offshore

Plywood cargo proa boat built in the Marshall Islands. Credit: Rob Denney

When he returned he upscaled his design and spent 18 months creating an 80ft cargo proa.

It cost him $50,000 AUS (£26,740), weighs just 3 tonnes and carries 10 tonnes of cargo.

The success of the cargo ferry concept has led to some interesting spin-offs, which Rob calls ‘Orbiters’ and describes as, “a fast, comfortable sail boat, rather than an over rigged, overweight source of income for repair people at every port of call.”

His website reveals some clever designs such as the Orbital University with student sleep-pods, and a Medical Services boat (complete with operating table) for doctors and dentists who want to support remote villages and islands, as well as providing a rapid-response boat for areas hit by natural disaster.

“Apart from the beams and the masts, the rest of the space is available to your imagination,” says Rob.

“Instead of mandating a payload and a layout that dictates what you can put on board and the size of the rig required, we are going in the other direction.”

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