Outboard Powered Fast Fun on the Water


Build this high-performance personal watercraft and power it with an outboard engine. It was featured in Popular Mechanics magazine. Make a great father/son project.


Plans include six 17 x 22 inch drawings and a 36-page, photo-illustrated book.



At rest, HydroRunner sits low in the water like a Cheetah poised in deep grass. Squeeze off a handful of throttle and she leaps onto plane and skims across the water at 40 mph. On plane, the tunnel-hull design gives a sure-footed stability that is unmatched by PWCs with conventional V-hulls. Turns are flat like a hydroplane.  Stability comes from the super-wide beam, which is camouflaged by her patented tri-hull design.  In reality, HydroRunner’s hull is about half as wide as it is long. Instead, she turns flat, more like a hydroplane (Click for Video). For a quick turn, back off on the throttle, crank the handlebars to one side, then apply full throttle. HydroRunner will swap ends and head off in the opposite direction almost within her own length. At high speeds, wake is normally taken with a giant, airborne leap. But hit a wake at speed on the down side of a jump and she’ll go straight through it, rather than over it.

Power can come from any short-shaft outboard of 25 to 30 horsepower.  The throttle lever is a standard bicycle brake lever attached by a cable to the engine’s throttle mechanism. Releasing the throttle lever returns the engine to idle. A standard shut-off lanyard is attached to the rider’s life jacket so the engine will immediately stop in the event of an unexpected departure from cockpit.    During tests, the engine stops as the rider is leaving the cockpit and HydroRunner comes to rest only 3 or 4 meters away.  The prototype was put through the US Coast Guard safe-powering pylon tests to document that she can handle the high power.   Every new high-powered small watercraft also has to pass the same tests.

Most of the expense of building her is in the cost of the engine. New, the engine can run $3,000 or more. A used engine can be purchased for $600 – $800. Figure another $700 for enough plywood, fiberglass, and fixtures to finish the craft.  HydroRunner is made primarily of 1/2-inch and 1/4-inch plywood, which is then covered with a layup of fiberglass. Most of the fixtures are standard boat items.

The tunnel hull wetted area was designed by Ron Ehde.  If you’re a fan of tunnel hulls, you’ve probably heard his name.  Ron designed the tunnel hull boats for Eliminator Boats.  And his tunnel hulls held the National Championship in drag boat competitions for ten years.  He was invited to join the project early on, as soon as Popular Mechanics decided they wanted to go ahead with the HydroRunner concept.  Ron is undoubtedly the nation’s top tunnel hull designer.

Additional information

Weight .75 lbs
Dimensions 13 × 10 × .75 in

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