They spend much of their life submerged and out of sight — or unnoticed on the transom when not in use — but propellers are to boats as tires are to cars: You aren’t going anywhere without one (unless, of course, you’ve got a sail and some wind).
The techniques used to manufacturer these crucial propulsion parts have been around for nearly 6,000 years. This video from Yamaha Outboards shows how workers take a simple wax casting and produce a precise piece of mechanical gear for use on today’s outboards.
Despite the age-old techniques used to make them, the basic form of modern boat propellers has been around for a little less than 250 years. The British Royal Navy used a primitive one on Turtle in 1775, the first submersible used in combat.