He Built a Full-Size Boat in His Yard—and Powered It With a Custom Hybrid Car EngineMotorBiscuitRahaan MazumderThu, September 17, 2026 at 12:00 PM UTCAdd us on GoogleBuying a boat is notoriously expensive, and maintaining one is even worse. But for the guy behind the YouTube channel Nasatchannel, dropping a fortune at a marine dealership wasn't an option. Instead, he decided to just build an entire full-size boat from the ground up in his yard.And he didn't just slap some wood together and call it a day. He constructed a massive fiberglass hull from scratch and engineered an incredibly clever hybrid powertrain using an old car engine.Now, creating a full-sized boat hull without an industrial factory setup requires some serious creativity. To get the massive shape right, he started by cutting and laying out standard sheets of plywood to act as a base mold. After treating the wood with a mold release wax, he laid down large sheets of fiberglass and soaked them in epoxy resin.AdvertisementAdvertisementOnce the initial shell cured into a solid structure, he added a brilliant DIY trick to keep the hull walls from flexing under the pressure of the water. He took standard plastic PVC pipes, cut them in half lengthwise, and bonded them vertically along the interior walls using more fiberglass and epoxy. This created a rigid, ribbed skeleton that gave the walls massive structural strength without adding a ton of excess weight.After sanding the exterior smooth, he painted the bottom a dark marine red and the top a high-visibility blue, giving it a legitimate, professional look.The Mitsubishi Hybrid PowertrainThe hull is impressive, but the real magic is hiding under the deck. Instead of taking the easy route and strapping a standard outboard motor to the back, he engineered a custom inboard drive system.Sitting right in the center of the boat is an old four-cylinder Mitsubishi car engine. But he didn't stop at internal combustion. He mounted a 13-kilowatt, three-phase electric motor directly in line with the Mitsubishi engine and the marine gearbox.This setup effectively turned the backyard boat into a modern hybrid. The electric motor can spin the propeller entirely on its own, allowing for completely silent, low-speed cruising around the docks. When he needs to cover more distance or pick up speed, the gas engine fires up to take over the heavy lifting. Even better, when the combustion engine is running, it spins the electric motor, turning it into a generator to recharge the onboard battery bank.Custom MachiningHooking a car engine to a boat propeller isn't a plug-and-play operation, and Nasatchannel had to machine several critical components from scratch.AdvertisementAdvertisementUsing a metal lathe, he custom-turned the solid propeller shaft and made heavy-duty flanged couplers to handle the torque. He even machined his own seacock strainer—the metal grate that sits on the bottom of the hull to pull in cooling water for the engine while blocking weeds and debris.To keep the intense vibrations of the car engine from shaking the fiberglass hull apart, he mounted the entire powertrain on a custom iron frame isolated by heavy rubber dampeners. Finally, he routed a classic stainless steel ship's wheel to the rear rudder using a steel-reinforced cable system, hooked up a throttle lever, and hit the water.Seeing a completely homemade, car-powered hybrid boat cruising smoothly down a river is undeniably cool, and it proves exactly what is possible with enough garage tools and determination.