History

• In the early 1800s, most steam-powered ships were propelled by paddle wheels. In 1839, the "Archimedes" became the first steam-powered vessel to be propelled by rotating propellers called screws. The "Archimedes" became a hot topic in the boating world and soon screw steamers were considered faster and more efficient than paddle steamers.
  
  

Propellers

• Unlike paddle wheels, the screws (propellers) on screw steamers were completely submerged and rotated on a fixed axle. The screw-like propellers of early screw steamers were refined over the years and resulted in the modern propellers that push most boats today.
  
  

Sails

• As screw steamers were developed and improved upon, many in the boating industry became less reliant on wind power to move ships. By the 1900s, most large-scale, steam-powered commercial vessels were screw steamers without sails.
  
  

The "SS"

• Originally, "SS" before a ship's name referred to "screw steamer" to distinguish it from a paddle steamer ("PS"). "SS" now means "steam ship."
  
  

Modern Implications

• The advent of screw-steamer technology led to many propeller-based modes of transportation in the modern era, such as airplanes and submarines.