Wednesday, October 7, 2015

Trans-Ocean Pedalboat

Davey du Plessis is an author, inspirational speaker and an adventurer who pushes himself far beyond the limits of us more normal people. He has ridden around the perimeter of Africa on a bicycle. He was doing a source to sea solo navigation of the Amazon River when he was ambushed and shot, then had to get himself back to civilisation. He was tested close to his limits in that adventure and still has the bullet lodged in his heart.

Davey's planned next adventure is to pedal a boat around the world. He approached me to design the boat and had his uncle, Tertius du Plessis, build it for him. The boat is now mostly complete and will soon be ready for testing.
Looks like a hi-tec starfighter but really a low-tec pedal boat.
While I designed the boat, I didn't design the propulsion system, which consists of a leg that has a conventional pedal arrangement at the top, inside the boat, and a plastic 2-blade propeller under the hull. The slow-rotating propeller has soft blades to reduce the chances of damaging marine life.
Exterior view, looking like it came from a Star Wars movie.

The styling looks very sleek and possibly intended for high speeds but high speed is not the aim. It is designed for low drag both in the water and above. A human-powered boat needs to be easily driven, to maximise the distance that can be covered for each unit of energy that goes into propelling it. That means that it must offer little resistance to the water and the air. The underbody is shaped for low drag at low speeds and to be easily steered in downwind tradewind conditions. She has a shallow barn-door type rudder, transom-hung.
Builder Tertius du Plessis with the boat during construction.

Davey is sure to find very bad weather many times on his voyaging, so his boat is also shaped for low resistance to breaking waves that strike it and it is shaped to roll back upright when (rather than if) it is capsized. Stability comes from the tankage and stowage compartments placed low down in the hull to lower the centre of gravity. The deck and cabin are shaped to float the boat high if inverted with the hatches and ports closed, to make it unstable upside-down. Davey will also be able to use his own weight inside the boat to help it roll back to upright if needed.

Construction is stitch-&-glue plywood, assembled over permanent bulkheads and partial bulkheads. The interior is divided into three compartments, separated by full bulkheads with companion hatches. Both ends are berth length, to accommodate one or two crew for a voyage.
Interior view of the cockpit. Full bulkheads separate bow and stern.

This coming weekend sees the Cape Town International Boat Show and Davey's boat will be on display.

This boat is not yet on our website but you can see our other designs at and

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