It’s often said that necessity is the mother of invention, but even a casual look at early U.S. patents makes it clear that the needs were as much inventions as the inventions themselves. Did anyone ever really need a helmet with shelves inside for potted cactus plants to supply oxygen to the wearer? Probably not, but in 1986 Waldemar Anguita was granted U.S. Patent No. 4,605,000 for it. If not need, what? The British philosopher Alfred North Whitehead came closer to the driving force behind invention: “Inventive genius requires pleasurable mental activity as a condition for its vigorous exercise.”

Clay Wright found that pleasurable mental activity in imagining ways to equip small boats with pedal propulsion. “I have a strong interest in unconventional human-powered boats and enjoy sketching offbeat propulsion systems.”


Clay’s HIYU is a Fiddlehead canoe, designed by Harry Bryan for double-bladed-paddle propulsion.

That interest led to his building of a 10′6″ Fiddlehead, a decked canoe designed by Harry Bryan. The canoe was designed to be used with a double-bladed paddle, but Clay had something else in mind for his Fiddlehead, which he christened HIYU.


The combination of pulleys in the cockpit with the gears beneath the hull give the system an 1:11 drive ratio, so pedaling at 50 rpm spins the prop at 550 rpm.

He devised a pedal drive that used a long V-belt from a large die-cast pulley on the horizontal pedal axle to a small pulley on the forward end of an outboard’s propeller shaft. On the outside of the hull was the outboard’s lower unit rotated 90 degrees with the skeg pointing forward and the driveshaft facing aft, with the propeller attached to it.


An old outboard motor gearbox was reoriented for use on HIYU. The skeg is pointing forward and the shaft that once was driven by the motor now drives the prop.

The mechanism was simple, but there was an ergonomic problem that could be easily overlooked in the design process: “Lifting one’s horizontal leg on the upstroke of a pedal-powered boat is an issue,” Clay discovered. “The first ten minutes of any cruise I take in little HIYU makes my quads burn, and I think there is no way I can keep it up.” In time Clay grew accustomed to the unusual cycling position, but HIYU’s performance was only a qualified success. HIYU, but the way, is a word in Chinook jargon, the 19th-century trade language of the Pacific Northwest. It means “plenty,” but in this case, plenty wasn’t enough for Clay.

Steve Navratil

CLATAWA is a Monk plywood skiff with a few changes Clay made to enhance the boat’s curves.

He started again from scratch and built a 9′ flat-bottomed skiff, designed in the 1940s by Edwin Monk as an easily built rowboat. Clay christened the finished skiff CLATAWA, a Chinook verb meaning “to go.”

His “vigorous exercise” of invention resumed with a new focus for the drive mechanism. “My main objective was to find an alternative to rotary input, i.e. bicycle pedals, which virtually everyone who builds these vessels employs, including me with my double-ended canoe. Reciprocating foot pedals and hand levers could provide linear inputs much like an elliptical exercise machine.” Clay recognized that reciprocal motion applied to a human-powered boat would be nothing new. Another Bryan design, the Thistle, is a slightly larger boat than the Fiddlehead and is equipped with a reciprocating-pedal drive that wags a flexible fin like a fish’s tail. And the highly successful Mirage Drive for sit-on-top kayaks uses pedals that move back and forth to power its flexible fins. But as Clay noted, “I’ve never seen reciprocal motion be converted to rotary motion to rotate a propeller.”

Clay Wright

Nearly complete but still in the works, Clay’s mechanism is wonderfully complex.

Clay made a mockup with PVC pipe for the frame that would occupy the bow of the boat and support the pedals and hand levers that would supply the power to a new drive system. The skiff’s power would come from the skipper operating the system like, as Clay put it, “a seagoing elliptical exercise machine.” He followed the mock-up with construction of working mechanical systems in metal. In the shop, everything worked as it was intended to.

Steve Navratil

The copper-pipe pedal system has pedal pads and hand grips for leg and arm power. The levers on the seat are used for steering by shifting each propeller between forward and reverse.

What Clay calls “the engine room” is even more complex. Here’s how he describes it: “The large pulleys are plagiarized from Phil Thiel; the near pulley is fixed to the copper shaft and therefore a driver. The far pulley is a freewheeling idler that returns the twisted V-belt. The little pulley is mounted to and drives a 1/2″ shaft which passes through the wooden tower. The aft small pulley receives the V-belt and turns a 3/4″ tube that encloses the 1/2″ shaft.  Therefore, we have two shafts on a common center that are rotating opposite directions.”

Steve Navratil

The black drum at lower right is wrapped with the cord that is connected to the pedal system in the bow. These drums are equipped with bearings that spin in only one direction. One of the large pulleys transmits the power to the center fore-and-aft shaft. The other large pulley is free-spinning. The shifting between forward and reverse is accomplished by the upright pins that move the yellow drive belts between the center drive shaft and the propeller shafts.

The yellow drive belts move to switch the prop rotation from forward to reverse. Again, here’s Clay’s description: “The horizontal bars on the clutches move the nylon rollers forward or backward to shift the belts. Note the pulleys on the propeller shaft that have one wall sawn off. Mounted in front of them are simple bearings. When either of the belts is shifted to its respective pulley, the propeller shaft is driven. The other belt is simultaneously shifted onto the bearing, where it freewheels helplessly and doesn’t drive the shaft. In this way, forward and reverse cannot be engaged at the same time.”

Clay Wright

Twin counter-rotating propellers provide power and eliminate the need for a rudder.

CLATAWA’s early sea trials did not live up to Clay’s hopes. After the first outing, he reported: “I am very disappointed with the boat. She just wouldn’t cooperate. One problem after another (the drive is overly complex), weeds clogging the propellers, etc., and I could hardly get the boat to go at all. I’m feeling that the boat is a failure. The boat is back in the basement. I’m going to throw a sheet over her and try to put her out of my mind.”

Steve Navratil

While Clay may have been disappointed with his prop drive, his boatbuilding yielded pleasing results with a shapely hull that sits in perfect trim with him aboard.

If the boat were the point of the exercise and designing the drive was simply a means to an end, CLATAWA might well be considered a failure. But it took only a few days for Clay to recall the project’s beginnings: “I concocted this admittedly impractical design for the challenge.” And he confirmed the connection between “pleasurable mental activity” and invention: “I had a great deal of fun puzzling out the challenge of converting linear movement into rotary motion.” The poor performance of CLATAWA was not a dead end but a path to escape the disappointment by taking up the challenge again.

One of the factors that had hampered the drive system’s performance was the nature of reciprocating motion: while a circular motion can continue without interruption, a reciprocating motion comes to a brief stop every time it changes direction. This isn’t an issue with the Mirage and Bryan fin drives—the fins also have a reciprocal motion and it’s what makes them work. But the propellers have a rotary motion, and they come to a stop and create drag rather than propulsion when the pedals change direction. Clay considered a flywheel to store energy and keep the props spinning in between pedal strokes. Unfortunately, he estimated that a flywheel for his drive system “would need to weigh about 80 lbs to be effective, and the boat weighs a ton as it is with all that mechanical nonsense. I think what would help the most is maximizing the pedal stroke length so the propellers would get in a good, prolonged spin before slamming to a halt. I’ll ponder a little more over the winter.”

CLATAWA’s drive system is not yet finished, but it is being worked on even if Clay is only thinking about it. The creation of something new is an essential human pursuit. The pondering is the point.

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