Using Hydrofoils to Improve Boat Performance

By Capt. Vincent Daniello.

In my early days as a captain, few boats cruised faster than 30 mph. Back then, bigger engines and the fuel they burned added too much weight, netting little more speed. Today, even modest performers top 50 mph thanks to lighter engines and boat construction, where more ponies push fewer pounds.Electric propulsion leaves boats yet again ­struggling in that extra-­pounds paradigm. ­Adding fuel—­
measured in kilowatt-­hours of lithium batteries—attenuates attempts to go faster and farther, at least until batteries become lighter. But there might be another way. I tested an electric-powered SunTracker Party Barge 22 DLX both before and after Hydrofin installed its hydrofoil system, which lifts a boat while moving through the water. This effectively overcame 800 pounds of lithium iron phosphate (LiFePO4) batteries—40 kilowatt-hours—that fueled twin Elco EP-50 electric outboards. In the end, flying on foils increased the boat’s speed by well more than a third and improved efficiency markedly. So, what are hydrofoils, and can they enhance performance aboard other boats too?

Performance Takes Flight

“We’re a long way from batteries that provide lightweight energy. Our hydrofoils create lift to overcome that additional weight,” says Jason Minor, Hydrofin’s founder. The patented system, engineered by noted catamaran and America’s Cup sailing foil-design firm ­Morrelli & Melvin of ­Newport Beach, ­California, utilizes powder-coated aluminum foils—essentially underwater wings. Mounting pads epoxied to hulls allow incremental adjustment of location and angle of attack, so Hydrofin foils lift nearly half a boat’s weight. “A typical bi-toon with a gas 150 runs around 30 mph. Adding Hydrofin foils can easily make it run 37 to 39 mph,” Minor says, adding that 30 percent better economy is common at cruising speeds. Riding higher on wings makes boats run smoother, dryer and quieter too.