If you're going on a self-propelled river journey, is it really self-propelled if someone drives you back to the start when you're done? Perhaps not – and that's part of the reason British entrepreneur Ben Kilner created a convertible paddle-board/bike-and-trailer combo known as the Duckleberry Finn.
We last heard from Ben just this June, when he was in the process of pedal-paddling from the navigable source of the River Thames to its outlet into the North Sea. He was doing so in a homebuilt canoe-like watercraft called the Jamima Paddleduck, which incorporates an ingenious bicycle-derived pedaled drivetrain that he invented.
The aptly named Pedal Paddle system's primary pedals are on one partial bike frame, mounted in front of the boat's seat. A chain drive runs from that frame's crankset to the crankset of another partial frame in the rear. It has a couple of paddles mounted on its own set of pedals. Therefore, as Ben pedals in front, the paddles alternately move up and down through the water, in the back.
An additional handheld paddle is used for steering.
The sit-on-top Duckleberry Finn utilizes the same basic drivetrain, which is mounted on a wooden frame that is in turn strapped to the deck of a 12-foot (3.7-m) inflatable paddle board. And while a partial bicycle frame is still used in front, a full upside-down bike frame is used to turn the paddles in the rear.
As long as the craft is traveling on the water, it stays in the described configuration. Once it reaches the takeout, though, the rear bike frame is removed from the wooden frame, gets its paddles taken off and its wheels put back on, and thus becomes a complete and functional bicycle.
The rest of the drivetrain is then taken apart, although the wooden frame subsequently gets reassembled into a small trailer – the wheels for both that trailer and the bike are carried onboard while the Duckleberry Finn is in "river mode." Once the paddle board has been deflated and rolled up, it's put into the trailer along with various other parts of the system. The bike is then used to tow that trailer back to the user's car, home, or wherever else they want to go.
Kilner put the Duckleberry Finn to the test this summer, when he used it to pedal-paddle approximately 100 miles (161 km) from the navigable source of the River Wye at the Welsh village of Glasbury, to the last exit on the river's tidal section at the town of Chepstow. He then converted the craft to its bike-towing-a-trailer "road mode" configuration, and rode it about 50 miles (80 km) back to the starting point.
"It was an absolutely magical trip," he told us. "Probably my favorite adventure so far. Scorching hot with very shallow water after a long drought left lots of shingle exposed and created rapids where it would normally be pretty smooth. The shallow water definitely provided a good testing ground for the niche abilities of the Pedal Paddle system."
He did add that some improvements still need to be made. The angle at which the paddles enter the water has to be tweaked, for example, plus the trailer's frame needs to be more rigid. The whole setup also has to be made lighter, as he estimates that it currently tips the scales at around 110 lb (50 kg).
"To build it up into a boat took about 1.5 hours," he said. "With additional product development this could be reduced to about 30 to 45 minutes, I think. It took about 2.5 hours to convert it from river mode to road mode, and then about another 30 minutes to make it more rigid. With more product development, this could be reduced to about 45 minutes."
Keeping such improvements in mind, Kilner has partnered up with some "engineering buddies" to produce a manufacturable design and ultimately a commercial product. He informs us that they plan on offering DIY plans, a Pedal Paddle frameset that could be adapted for use on third-party paddle boards or canoes (river mode only), and a Pedal Paddle Amphibious frameset that could be converted into a bicycle-towed trailer.
You can follow his progress and register for updates via the Pedal Paddle website – he's also looking for investors, should you be interested. His adventure on the River Wye is documented in this video.
"It's just such a nice feeling to be able to think of something, make it, then go exploring with it," he said. "It's genuine satisfaction."
Project website: Pedal Paddle