Ship shape

It may be a throwback to the clippers of the 1930s, but the Maltese Falcon is the design of boats to come, with an automatic rigging system complete with sensors to help improve performance.

When it enters the water for the first time early next year the Maltese Falcon will become just about the most advanced privately owned yacht in existence. The 87.5m vessel, which is in the final stages of construction at the Istanbul shipyard of Italian superyacht specialist Perini Navi, will also be one the largest and fastest personal sailing boats in the world.

The boat is a clipper, the kind of vessel that ruled the sea in the golden age of sail. Renowned for their speed — Maltese Falcon is expected to be capable of 18–25 knots — clippers use a slender hull and a square rig, where the main horizontal spars (or yardarms) are perpendicular to the keel. By contrast, other big sailing vessels, such as schooners or sloops, typically use fore and aft rigs which consist of sails that are set along the line of the keel.

Gerry Dijsktra, the acclaimed Dutch naval architect who has been responsible for the overall design of the yacht, explained the decision to go for a clipper.

‘The brief was for a fast boat — and if you want that then of course you go for a square rig and not a fore and aft rig because a square rig goes harder on the ocean.’ This is an important consideration, as the boat’s billionaire owner, Silicon Valley pioneer, venture capitalist and longtime sailing enthusiast Tom Perkins, has reportedly set his sights on some of the speed records set by earlier racing clippers.

But while notable for being one of a very small handful of clippers to be built since the 1930s, the yacht’s real claim to fame lies in its automatic rigging system.

Known as Dynarig, the concept for the system was first hit upon in the 1960 by German hydraulics engineer Wilhelm Prolss. His vision was for the use of hydraulic motors to ensure that the mast, yards and sail surfaces would be automatically aligned with the wind.

Prolss envisaged vessels with over six masts and sail areas of 12,000m2 that could be operated by a crew no larger than those on diesel-powered vessels. He believed that his technology could be applied to tankers, bulk carriers and even cruise ships to create big, fast, automated sailing vessels capable of speeds of up to 18kt. Sadly for Prolss, despite numerous attempts to interest shipbuilding companies around the world, no one was prepared to build his system — until now.

The rigging system for the Maltese Falcon — designed and developed by UK carbon fibre specialist Insensys — is a little smaller than that envisaged by Prolss. But it is no less innovative, still pretty huge and, most importantly, it has been built.

Damon Roberts, director of the Southampton company, explained that while traditional mast designs call for the use of stays — the lines that keep the mast upright — high-strength T800 carbon fibre has enabled the team to design and build three 57m freestanding rotating masts. Each of these 13-ton masts is supported by a giant nine-ton bearing and has attached to it six fixed carbon-fibre yards which, unlike those used on a conventional square-rigger, have a built-in camber of 12 per cent — in other words they are curved.

Each mast also has five sails, which are set between the yards in such a way that when deployed there are no gaps in the sail plan — effectively enabling the whole set of sails to work as one.

The sail is trimmed to the wind direction by rotating the mast — but, explained Roberts, the fact that there is no restriction on rotation, combined with the curved yards, and the lack of gaps in the sail plan, lends the rig improved aerodynamic efficiency compared to a square-rigger.

According to Gerry Dijkstra, the Dynarig is around twice as efficient as a conventional square rig.

Roberts explained that a number of major structural issues had to be dealt with during the design of the freestanding rigs. This isn’t surprising considering that they will be subjected to bending loads of around 18,000,000NM — ‘three times that experienced by the biggest wind turbine that’s ever been built’, according to Roberts.

One of the biggest complicating factors in the design was the fact that the sails, when not in use, furl into a cavity in the body of the mast. ‘This cavity and the entrance of the cavity, by the nature of the design, are down the compression side of the rig. So not only do we have to deal with the big bending moment but we now have these slots between every yard to allow the sail to come in, right down the face of the rig that is working hardest,’ explained Roberts.

Indeed, the challenges thrown up by this cavity have been one of the biggest stumbling blocks to the development of Dynarig systems in the past. Before the advent of high-strength composite materials engineers would have constructed the mast from metal, but the addition of this cavity would have made it extremely difficult to build a metal mast with sufficient stiffness.

‘The rig really became feasible after recent developments in composite materials,’ agreed Dijkstra, ‘and the ability to build carbon-fibre spars. You really need carbon laminates to make the whole thing work because of the combination of stiffness, strength and weight,’ he said.

The other key aspect of the system’s operation is the winching mechanism used to set and furl the sails. This has been developed by Perini Navi, the largest production builder of superyachts which, working closely with Italian hydraulics specialists Cariboni Spa, is well known for developments in sail handling on large sailing vessels.

The system developed for the Maltese Falcon uses five electric winches for each sail: four electric outhaul line motors that pull the sail outwards, and one winch to drive the mandrel that furls the sail to the mast.

According to Dijkstra, this automated system, which can be operated by a portable control panel, can set a single sail in 75 seconds and the entire 2,396m2 of sail area in just six minutes.

One of the big advantages of the system, he added, is that it doesn’t require many people to operate it. Although the yacht will need a large crew for maintenance, docking and domestic services, Dijkstra claimed that it is theoretically possible for a single person to sail it.

But despite the fact that the entire system has been designed to be as tough and rigorous as possible, there are still limits to the technology. ‘As with any multi-masted yacht the design issues are such that you can’t really engineer the rigs to take anything that the weather and sea can throw at them,’ explained Roberts. This, of course, means that the crew has the potential to damage the rigs if they use the wrong sail configurations in the wrong weather conditions. So, to help them make the right choices, and to better understand the properties and the behaviour of the rig, Roberts’ team has brought its expertise in the area of fibre-optic sensing systems to bear on the project.

Insensys has equipped the rig with an embedded mesh of fibre-optic devices. These sensors — which change their light transmission characteristics in response to stress and strain — report directly to the main control panel on the bridge and give the crew a clear indication of the status of the loads on the rigs. This helps them to understand and build up a working knowledge of the rigs and also give them advance warning of potentially catastrophic strains.

While fibre-optic sensing systems are not entirely new to the world of yacht design, what is particularly innovative about the system on the Maltese Falcon is that, as well as providing information on strain, it will also be used by the crew to improve the performance of the boat.

Roberts explained how the nature of the rig’s design, coupled with the fibre-optic sensing system, will enable those sailing the boat to effectively treat it like a real-time, full-size wind tunnel model.

‘Because the rigs are freestanding they have no other attachment to the deck. So by monitoring the forces within the rig we can resolve those into driving force and drag force, and that will be displayed on the bridge as a drive force/ drag force ratio which will enable them to optimise the rig setting on any course,’ he said.

Roberts claimed that while the technology has already been used in a similar capacity for active blade pitch control in the wind turbine industry, its application to improving sailing performance is a first.

Clearly, the development of the Maltese Falcon, or possibly any privately built superyacht, is a very different proposition from most other big engineering projects. But while the owner, Tom Perkins, is obviously an exceptionally wealthy man — the cost of the boat is put at $50m–100m (£29–58m) — Roberts insisted that the boat is far from a ‘gold tap’ project.

‘Things have always got to be done in a cost-effective way — money is an issue.’

Indeed, Perkins’ patience and sound understanding of the technical issues has, said Roberts, been a key element of the project’s success so far. ‘You don’t come lightly into a project like this. We knew we were stepping into some quite big unknown areas and we wanted to minimise the risk.’

Roberts said that Perkins has given the Maltese Falcon’s design and development team the freedom to carry out any testing and development work that it considered appropriate.

This has included building a 40th-scale model of the rig, carrying out wind tunnel testing on a sixth-scale model and finally subjecting a 1:1 scale land-based prototype to tests for 18 months.

‘It’s a highly unusual project because it’s going into some very novel areas, so there’s no precedent. Too often there’s a temptation to have a fixed price, goal and schedule and try to do something very quickly which is not properly developed. The owner has been very understanding and sympathetic to the idea of risk-reduction processes.’

Depending on the weather, the boat should be going into the water for the first time just after Christmas, with sail trials in spring, and Tom Perkins taking delivery of it shortly after that.

But will the technology deployed on the Maltese Falcon find its way on to other boats? Roberts certainly thinks so. ‘I feel that large freestanding rotating carbon spars will inevitably come into other big yachts because they will greatly simplify the handling and increase the safety. If you eliminate the rigging you eliminate a major interface problem on the rig and with carbon fibre you overcome the problems sailing yachts have with fatigue and weight. We will see more big yachts going down this route.’