Awesome Propellers

Ships of all sizes need propellers to move through the water. Process X takes us on a tour of Japan’s Mikawa Propeller Co., Ltd., a factory that makes precision marine propellers by casting bronze in sand. After the melting and casting process, workers remove excess sand, painstakingly grind away excess metal, and polish propellers to a smooth finish.

Paddling a kayak can take a lot of strength and isn’t very fast. In the interest of decreasing effort and increasing speed, inventor Colin Furze made a custom kayak paddle with a powerful motor and propellers to give things an extra boost. But is Colin’s idea a breakthrough or a bust?