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. Makes a great father/son project.
Instant Downloadable! Plans include the original architecture shown in Popular Mechanics plans, plus an upgraded version with 3D Solidworks Models and eDrawings models that can be viewed on an ordinary PC. Available on Instant download.
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 $3,500. A used engine can be purchased for $600 – $800. Figure another $700 for enough plywood, fiberglass, and fixtures to finish the craft. The first generation HydroRunner was 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. This new architecture is based on fiberglass over foam.
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.
The plans on instant download include an early release of a new and lighter architecture. which has been modeled in 3D CAD – Solidworks. It’s shown in the image above on the left. This results ijn a stonger and lighter hull which can accouht for the greater weight of modern engines with emssion controls. HydroRunner is still rated to US Goast Guard standards for 30 hp and two occupants. The new design features a more comfortable seating position, much like a crouched motorcycle riding position. Plans also detail the original plywood hull. The white boat in the images above used an early verion of this foam-filled architecture. Until now, it has never been offered to the public. The new design also includes a BayStar hydraulic steering system and a removable fuel tank. .