The earliest knowledge of ships comes from Egyptian rock drawings dating from 6000 BC. Wood was the most popular material for shipbuilding. However, some early civilizations had no quantities of wood. In Mesopotamia, the first boats were built out of inflated and stretched animal skins and clay pots. The Egyptians used reeds. Early wood boats included: rafts, canoes, and dugouts.
Floating buoys have existed before the 13th century.
Robert Foulis invented the steam fog-horn. Foulis' horn was the first to hoot automatically in foggy weather in 1825.
The gyroscope was used as a tool to study the earth's rotation.
Martha Coston invented a system of maritime signal flares based on color and pattern.
The protractor is an instrument used to construct and measure plane angles. The simple protractor looks like a semicircular disk marked with degrees, from 0º to180º. The simple protractor is an ancient device. The first complex protractor was created for plotting the position of a boat on navigational charts. Called a three arm protractor or station pointer, it was invented in 1801 by Joseph Huddart, a U.S. naval captain. The centre arm is fixed, while the outer two are rotatable, capable of being set at any angle relative to the centre one.