This is the story of an idea finding its time. Like all good stories it starts on a dark and stormy night. Mid-Atlantic, February 1981, the moon racing through the clouds, lighting a black and white chaos of leaping water. Again and again the classic 30m schooner Marie Pierre (now Aschanti IV) was brought to a shuddering halt by head seas. As skipper, part of me routinely balanced course to steer and sail to carry, with available muscle power. Meanwhile a question occurred. Why is it not possible to use some of the stupendous wild energy in the waves to propel the boat forward, rather than stop it in its tracks?
I don’t know why the question stuck. By the time I was home a year later, five ways to use wave energy to drive a ship had sprung to mind.
The sailor’s nightmare of a hull hinged in the middle was immediately dismissed.
Likewise the tanks with one-way valves that fill and empty to create a flow.
The sausage shaped waterwheel with a screw wrapped around its length is a pretty solution. No moving parts, just screwing its way around the world forever: but for what use?
The gimballed hold with the rolling motion converted by clutch bearings into a continuous shaft rotation to a screw propeller: might work.
Then there were the horizontal wings below the bow and stern. Imagine yourself at the bow of a ship, pointing into the waves, going nowhere. As the ship pitches there is a difference in relative motion between you and the water below. Put a small horizontal wing (foil or fin) into the water, hinged near its leading edge, and it will simply weather cock 180 degrees as the ship’s pitching takes it up and down. Add a resistance so that it has an angle of attack and it will drive forward.
Probably this was all some perpetual motion nonsense, but the last two ideas would not go away. In the end I succumbed. The back of a steel filing cabinet from the local dump got bashed into a 1m long hull shape. Four foils were fitted. A gimballed hold drove a transfer engine of toy cogs built in a Coleman’s mustard tin.
Taking care not to be seen by my neighbours, for fear of being laughed at rather than to protect the ideas, I borrowed my small son’s first fishing rod and launched my device into the estuary of the river Tamar nearby. The swinging hold was locked in place, so the first experiment was with the foils alone. Nothing happened. The foils stuck in the mud, the boat seemed passionately attracted to the shoreline reeds. After half an hour, wellies awash and in bad temper I yanked on the fishing line. It snagged and cut. The boat bobbed about, turned into the wind and waves, and set off across the estuary to nestle in the reeds a quarter of a mile away on the other side.
I can report there is a curious inward smile for such a moment.
In the pre-digitised Patent Office, a Dickensian experience not to be missed if you had a rainy afternoon to kill in London, I discovered I was not the first to wonder if and how the energy in waves could be turned to good effect. All the ideas described above were there, and some other horrors.
Most intriguingly Herman Linden of the Naples Zoological Station had built his ‘Autonaut’ in around 1895. Among his experiments was a 23 ft Autonaut fitted with flexible flaps bow and stern. This was reported to have made around four miles per hour while towing two other boats each with two people in them.
His suggested use was for small unmanned Autonauts to be sent off to spread oil upwind of ships in a storm, to calm the waves. It might have worked too, except the deck of a ship in a storm is quite dangerous enough without oil to convert it into a death trap.
I could get no interest in Britain until 1985 when the television programme Tomorrow’s World did a piece on a Norwegian, Einar Jacobsen, and his foil propeller*. His ideas and research paralleled mine. Professor Francis Farley at Reading University helped me by arranging a free day in a military wave tank. We came across further work going on at the huge Japanese ship builders Hitachi Zosen. Francis invited Hiroshi Isshiki from Japan and Einar Jacobsen from Norway to Imperial College London where we held the first international get together on wave power for ships. A lecture theatre filled with dark DTI suits.
Almost simultaneously the price of oil dropped and with it all interest. For 20 years I got on with earning a living. My sons who had helped me grew into men. With the new millennium came worries about ‘peak oil’ and climate change, and a desire to harness renewable energy. “Dad, why don’t give your wave powered boat a go?”
I couldn’t see the point. Not until another question intrigued me. All earlier endeavours had used existing hulls designed to be driven by engines for other purposes – freighter, fishing boat, frigate. What would happen if you designed the hull for wave power?
Turning naval architecture on its head, what if you maximised the pitching and rolling in order to use foils to convert the energy into forward thrust, as well as stabilising the vessel. What fun.
I built a 1.2 m hull. It went okay in open water, about one knot in all directions. But you can’t measure and tune accurately when floundering about in a rubber dinghy in constantly changing weather and tides. A university with a decrepit wave tank wanted £1,000 a day for its use. I built a 20m wave tank at the bottom of the garden for £300.
Some people fly gliders, some grow cabbages. For the next two years my hobby was trying every variation of foils size, shape and position in every height and period of wave, and with different ballast settings.
As a chronic New Scientist addict I became aware of the underwater gliders and buoys used for collecting ocean data. My little boat, if equipped with PV cells on the deck, a decent battery, GPS navigation and satellite communication could go – well anywhere and nearly forever. Still nobody was interested. Plymouth and Exeter Universities run a marine renewable energy initiative called Primare. At one of their events I bumped into an old friend who gave me a new contact. Two years later, with my hobby heading into cold storage again, Mark Scibor-Rylski put me in touch with David Maclean, MD of MOST Ltd. David had been to a MoD briefing on the future technologies the Royal Navy were seeking. He had mentioned my wave powered boat. “Oh, we could fund that 100%”.
And the rest as they say is history. In 2012 we formed a joint venture MOST (Autonomous Vessels) Ltd. We won government funding through the Defence Science and Technology Laboratory (dstl) and National Oceanography Centre (NOC). I patented the refinements and improvements I had discovered by designing a hull for the job, and new foil ideas. Importantly, as a salute to all those who had adventured with wave propulsion over the previous hundred years, I registered Herman Linden’s name “AutoNaut” as our trade mark.
Last week on sea trials our first 3m AutoNaut clipped happily along at 2.5 knots, we got well into making our first sale to the USA, we discussed a new use for AutoNauts and an agency agreement with Australia. Through sister company MOST Ltd a collaborative project with Rolls Royce is in the final contracting stage with the UK’s Technology Strategy Board under their ‘Vessel Efficiency’ programme. The right idea and the right time have finally come together.
* You can watch this BBC programme on YouTube http://www.youtube.com/watch?v=UWpxtfmpVD4. It is a good illustration of the principles.
A more general though still incomplete history of wave powered boats, with references, can be found at: http://folk.ntnu.no/eirikbo/wavepropulsion/index