Deck Sweeper Meaning in Sailing

A deck sweeper describes a specific type of mainsail with a very low bottom edge. The foot of the sail sits extremely close to the deck to block air. This design prevents wind from escaping under the sail which increases the overall aerodynamic efficiency. It creates a seal that forces the air to move across the entire sail surface. These sails are most common on high-performance racing catamarans and modern foiling boats today. One example involves a racing boat accelerating quickly because the sail touches the flat deck. The extra pressure generated by this seal allows the boat to reach incredible speeds. Using this sail requires the crew to be very careful when moving around the mast. The low height of the boom can be dangerous for people standing in the wrong spot. This technology represents the latest advancements in the physics of high-speed competitive sailing maneuvers.