Navigating At Sea

Before global positioning system (GPS), ships at sea relied on celestial navigation by the stars, sun, moon, and planets. The Quartermasters and Navigator used a sextant, chronometer, and nautical almanacs to determine the ship's latitude and longitude. Quartermasters maintained the ship's three chronometers for accurate time at sea, because knowing the exact time at the Prime Meridian in Greenwich, England, was essential for determining longitude; Greenwich Mean Time was compared with local time, with one hour of difference equivalent to 15° longitude. Once a week the ship received a time check from Washington D.C., and the Quartermasters compared it to the chronometers, checked and wound all of the ship's clocks, and kept them synchronized. Quartermasters also made weather observations, recording temperature, relative humidity, atmospheric pressure, wind, clouds, sea condition, and other phenomena, then sending the data by radio to shore-based weather stations, while on larger ships such as a battleship an Aerographer's Mate drew complete weather charts. In one recollection, while leaving Majuro through a narrow harbor entrance with a strong current under Captain Thomas, a ship needed speed to hold course as an LST patrolled outside on a collision course; the captain stopped engines to let the LST clear, then sent the message, "Are you familiar with the rules of the road?" and received the reply, "NEGATIVE." Commander Tolley used a sextant to measure the angle between the sun or a star and the visible horizon to determine the ship's location, while Chief Quartermaster Joe Ringhoffer recorded the time and sights, and another sailor held a stadimeter, a device used to estimate the range to an object of known height and to keep ships at the proper distance from each other when steaming in formation.

North Carolina · United States