But not always. As a teenager in his native city of Hamburg, Stefan Wrage had two hobbies: flying kites and sailing. Now, he thinks he has combined those passions effectively enough to transport the world's great shipping fleets back more than a century in time to a new age of sail.
Mr Wrage's sail is actually an elaborate kite to help capture the power of the wind, using the energy to supplement convention forms of power. In trials this year on the waters of the Baltic Sea, he has performed the nautical equivalent of reinventing the wheel. By switching to wind power during favourable conditions, energy costs could be slashed, perhaps by more than half.
The breakthrough from his Hamburg-based firm Skysails could be an idea whose time has come. For centuries, the wind was harnessed to carry man across the oceans. Then came the age of steam followed by the diesel engine, which killed off the great sailing fleets of the past.
But wind power has one big advantage: it is free. And, as the world gets used to paying more and more for oil, the possibility of being able to tap into a source of limitless energy for nothing has caught the imagination.
Mr Wrage hit on his notion of a kite-powered ship at the age of 15. "The idea came after I had experienced the huge power generated by flying my kite," he says, "the next day I went on a dinghy and it was going so slowly. And that raised the question, 'why can't we use the huge power of the wind?' I never understood why this was not possible'".
The same thought has occurred to others too. Historically speaking, previous attempts have been flops. In the 1920s, wind power propelled German rotor ships which operated on a form of cylinder. They failed to catch on.
In the late 1970s, Japan equipped at least five tankers with masts so that the vessels could become wind-assisted in favourable conditions. At that point, at least, greater savings could be made by technology that reduced manpower.
Several efforts have been made to create a modern, high-tech sail that could be fitted to contemporary fleets and turn them into hybrid vessels.
One Danish firm, Knud E Hansen, believes it has produced a product that could bring big cost savings for bulk carriers which sail slowly, particularly on northern routes.
It plans to equip ships with a high tensile steel mast with fibreglass panels fore and aft. Jesper Kanstrup, a senior naval architect with the firm, says that the system "can produce three times more power per square metre than a traditional sail".
He says the application is mainly for "large ships sailing slowly, like bulk carriers or tankers, sailing at about 13 knots. From computer animation studies we know that, it is certainly the case that, in the north Atlantic, it is a good idea that can save a lot of fuel".
There are downsides too, however, because the masts also produce drag. The refitting costs can be high and equipping a ship with masts makes loading and unloading it more difficult as well as taking up valuable cargo space on container ships.
The Skysails system avoids those logistical problems. Like many good inventions, the idea is very simple. Kites of anything between 750 and 5,000 square metres launched from a ship, flying between 100m and 300m above sea level, where wind power can be twice as strong as that which propels conventional sails.
It is operated with a computer autopilot and can be retracted by a winch during poor weather.
Its founder says it can be fitted on any type of ship up to an including the very largest, although the firm will start by equipping a mega-yacht, then move to bigger craft in 2007.
Its fitting costs of between €400,000 and €2.5m (£270,000 and £1.7m) are relatively modest by shipping standards and could be recouped in anything between two and five years depending on usage. And, because of the computer-operated autopilot, there are not many additional manpower costs to consider. "We don't say to people, don't use your diesel," says Mr Wrage, "but if there are good winds, throttle back a little".
Nevertheless, the idea is a challenge to the culture and thinking of an industry used to operating on a single energy source.
Simon Stephens, curator of the ship model collection at the National Maritime Museum, says that, because of the costs of buying shipping, innovations tend to take more time to feed through in the world of navigation. Thus, while hybrid cars are already advanced, there has been less work along the same lines in shipping.
He argues: "They are making headway but design developments in shipping goes at a slower rate than in the car industry.
"It takes time for things to come into operation with ships."
There are now good reasons why wind power seems more attractive now than in the last century. In the days of the great sailing fleet, journeys were completely at the mercy of the elements. Nowadays, modern satellite weather forecasting technology is highly sophisticated, allowing crews to plan around climatic conditions. Courses can be altered daily to take account of changing wind patterns.
The economics of the industry, which was set at a time when oil was relatively cheap, have altered drastically. Fuel used to be a small component of costs, compared to manpower but, with the reduction in crew sizes because of new technology, that equation has changed. Meanwhile, environmental issues have come to the fore, with new rules from the International Maritime Organisation on marine pollution requiring ships to shift to a more expensive low-sulphur fuel.
But the idea has never been an easy one to sell to a well-established global industry that wants as much flexibility and as few potential problems as possible.
"It is difficult to convince owners," says Mr Kanstrup, "first you have to show that you would have a reasonable payback time, and then you have to prove that the system is reliable and that there are not going to be technical problems with the ships." Mr Wrage, who is now 32, admits that, at first, he was seen as something of a crank. He says: "For the first two years, 'nerd' was practically the nicest thing I was called. People thought I was talking bullshit because the idea seemed so crazy.
"But when people start to think about it and start to put positive effort into exploring it, I get positive feedback." He now thinks he can break through into the mainstream and, in terms of the potential savings, says that circumstances will determine the benefits. One factor is the price of oil which he expects to be anything between $40-100 (£20-£50) a barrel in the coming years, or at any event "above the average price in the past decade", Mr Wrage says.
Whatever the price of fuel, he says: "Savings could reach 60 per cent, but each ship is different and it will depend on the amount of usage and the kind of ship. It could be 5 per cent to 10 per cent, it could be 30 per cent. In two to five years it pays back the cost of installation, which is fast for the shipping business when you consider that the life of a ship is 25 years."
Even with that large carrot dangled in front of their noses, those in charge of big fleets remain highly cautious, and one last week described the Skysails notion as a "non-starter for ocean-going vessels".
The main complaint is the fact that it is reliant on favourable winds. Worries also include the fear that, if there were a sudden alteration of course, the wind and the engine would be pushing in the opposite direction, putting a strain on superstructure, making steering more difficult (and using more fuel) and maybe even risking the ship. The practicalities of operating the kite also raise questions, particularly about the risk of it detaching in stormy weather.
Mr Wrage rejects many of the criticisms and points out that, because of its shape, the kite can be used upwind as well as downwind (unlike parachutes which have also been experimented with). He says that the force applied by the kite on the ship is no greater than that of an anchor and, because it is attached to the vessel at the same point, there is no need to put additional strain on the superstructure.
And he believes that the control systems are good enough to harness the maximum energy from the prevailing winds and to winch the kite in during stormy weather. However, he does admit that the launch and retraction of the device has been the most technically challenging aspect of the project and that, "in the very worst scenario" it is possible that a kite could be lost. "You cannot say it will never happen," Mr Wrage says. So seriously is the idea now being taken that he has, so far, raised up to €10m in investment in the project and is being supported by companies in the sector including Germany's Oltmann Gruppe. Environmentalists believe that this is a sign of a growing trend which is part of the psychological impact of recent shocks resulting in the dramatic rise in oil price.
Tom Burke, visiting professor at Imperial and University Colleges, London, argues: "You are going to see, around the world, people thinking, 'there is going to be trouble with energy, let's get smart'. People thinking they are getting ahead of the curve have an unblocking and dynamic effect. Ideas which have been around for some time are going to be picked up.
"You will not see the impact for three or four years but there is a lot of investment and energy efficiency is going higher up the project list. Psychologically, people are thinking a lot more about energy independence."
Mr Wrage puts it another way: "Wind power has been the driving force for shipping for a few thousand years. It is only in the past couple of hundred years that we have used oil-driven engines. When oil gets more expensive it is logical to say, 'wind is cheaper', let's use it again'".Reuse content