This video documents the extensive testing and performance optimization of a custom-built 14-foot electric catamaran. The primary goal is to enhance the boat's efficiency through systematic propeller testing and the integration of a hydrofoil.
Initial tests focus on finding the most efficient propeller. After a flawed first attempt, a more scientific method using a PixHawk autopilot to maintain constant speed reveals that different propeller sizes are optimal for different speeds; a larger stainless steel prop is chosen for higher-speed efficiency.
The main experiment involves adding hydrofoils to lift the hulls and reduce drag. A large, high-aspect foil proved problematic, making the boat less efficient and dangerously tail-heavy at speed. A smaller, repositioned wake foil offered more stability. Data analysis conclusively shows the foil only improves efficiency at the boat's absolute top speed (over 11 mph), where the displacement hulls become inherently inefficient. At all lower speeds, the foil simply adds drag. However, the hydrofoil provides a significant benefit in ride smoothness, allowing the boat to glide over choppy water. The video concludes with a top speed run of 17.4 mph on a 48V system without the foil, demonstrating the hull's impressive capability.
Boosting an Electric Catamaran: Propeller and Hydrofoil Performance Tests
0:00:02 Project Recap: The video follows up on the creation of a custom 14ft electric catamaran, built from 3D-printed foam cores and carbon fiber, with a design focused on efficiency.
0:02:48 Understanding Hull Speed: The boat's long, narrow displacement hulls are highly efficient, allowing it to easily exceed its theoretical 5.7 mph "hull speed" and reach 11 mph on a 24V system.
0:09:42 Scientific Propeller Testing: To find the optimal propeller, a PixHawk autopilot is used to maintain precise speeds for accurate efficiency measurements. The results show a smaller propeller is most efficient at low speeds (1.5 m/s), while a larger stainless steel propeller performs best at higher cruising speeds (3 m/s).
0:15:16 Hydrofoil Introduction: A large hydrofoil is bolted to the catamaran to test if lifting the hulls out of the water can reduce drag and further improve efficiency.
0:17:30 First Foil Test - Mixed Results: At low speeds, the foil increases drag and makes the boat less efficient. At higher speeds, it successfully lifts the bow but makes the boat unstable and dangerously tail-heavy, leading to a crash.
0:22:02 Foil vs. Hull Efficiency: Data analysis reveals a key finding: the hydrofoil is less efficient than the catamaran's specialized displacement hulls at most speeds. The foil only becomes beneficial at very high speeds where the hull's own drag curve rises sharply.
0:25:36 High-Speed Foiling & Ride Comfort: Combining 48V batteries with a smaller, more stable foil allows the boat to glide smoothly over choppy water. This demonstrates the foil's primary advantage is providing a much more comfortable ride at speed, not necessarily increasing efficiency.
0:27:37 Final Top Speed: With the foil removed, the catamaran on 48V power achieves a final top speed of 17.4 mph (28 km/h), an impressive three times its theoretical hull speed.
0:28:09 Key Takeaway: For this efficient hull design, adding a hydrofoil only improves efficiency at the very top end of its speed range. Its main benefit is significantly improving ride quality in rough conditions.