Hydroplaning RC Jet Boat Steers Clear Of Convention

April 19, 2025 by Seth Mabbott 19 Comments

[CovaConcepts], who has a background in motorsports, has been busy designing an unconventional radio-controlled watercraft she calls the HydraJet.

There are two key design decisions that make the HydraJet what it is. First, she chose to propel the boat by pushing against the air via an electric ducted fan (EDF) rather than the water via a traditional water propeller. This simplified construction and made it more affordable, partly because she already had the fan on hand.

Her other design choice was to use wings underneath the boat to lift it out of the water. Not as hydrofoils, where the wings ride below the surface of the water, but for hydroplaning where the wings ride on the surface of the water. Lifting the vehicle out of the water, of course, reduces drag, improving performance as we’ve often seen with high speed watercraft (including RC models) as well as slower bicycle-powered ones. The choice to rely on hydroplaning also reduces the complexity of the design. Certain hydrofoil designs need to make adjustments in order to keep the vehicle at a steady level, whereas a hydroplaning wings can use a static angle. Hydrofoils also must overcome challenges to maintain stability.

[CovaConcepts] hopes to eventually scale the HydraJet up large enough to carry human passengers and we’re looking forward to the opportunity to take it for a spin around the lake.

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Hydroplaning Boat Skims Over Water

June 29, 2023 by Lewin Day 3 Comments

Regular hulled boats are all well and good for rowing and all, but if you wanna go fast, you’ve gotta cut your draft. [RCLifeOn] built a hydroplane design that skims on the very surface of the water, and thus travels very quickly as a result.

The build came about as [RCLifeOn] has an upcoming race which he wishes to win with speed and finesse. To that end, he 3D printed an RC hydroplane, using spray paint and spackle to waterproof the parts. It’s a trimaran design, with the large central hull connected to two pontoons via carbon fiber rods. Propulsion is via a triple-motor fan setup on the rear of the boat.

The outer motors were initially used to steer the boat via variable thrust, which comes with zero drag penalty compared to a conventional rudder. However, they proved ineffective, and a servo driven rudder was used instead. Eventually, all three motors were reconfigured for forward thrust.

The boat worked well when it was able to get up to speed and hydroplane over the surface of the water. However, it was difficult to film, as even the weight of a GoPro was enough to keep it stuck on the water’s surface. Instead [RCLifeOn] used his electric surfboard as a chase rig to film the boat — a neat trick itself. Continue reading “Hydroplaning Boat Skims Over Water” →