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Ship Sailplan

A ship has three masts, all three square-rigged. This was the typical rig for clipper ships, Down Easters, and other sailing vessels in the deep sea trades.

The diagram is from the Nova Scotia Museum informational poster, Sailing Ship Rigs.

Brig Sailplan

A brig has two masts, both square-rigged.

The diagram is from the Nova Scotia Musuem Informational poster, Sailing Ship Rigs.

Schooner Sailplan

Schooners are fore-and-aft rigged sailing vessels, with at least two masts; the after mast is the same height or taller than the foremast. Until the middle of the nineteenth century, all schooners had only two masts.

The diagram is from the Nova Scotia Museum Informational poster, Sailing Ship Rigs.

Three-Masted Schooner Sailplan

Schooners are fore-and-aft rigged sailing vessels with at least two masts; the after mast is the same height or taller than the foremast. Three-masted schooners were also called tern schooners. The only 7 masted schooner was the Thomas W. Lawson. More commonly found in the latter half of the 19th and early 20th century coastal trade were 4 and 5 masters. A few six masters were built.

The diagram is from the Nova Scotia Museum Informational poster, Sailing Ship Rigs.

Bridge on Trawler Huntress 1979

View of the bridge aboard the 87-foot stern trawler Huntress, built at the Washburn & Doughty yard in Woolwich, Maine, in 1979. Note the radar monitor near the wheel. A modern bridge would have GPS, a fish finder, an auto pilot, and several radios. In this set up it is likely that the radio is out of view and there should be a LORAN available. This vessel has a compass with large compensators at each side, common on steel ships.

Solving Lunar Distances

This diagram illustrates how the moon appears to move through the stars. It shows that there is a difference between the measured altitude of the moon and its actual altitude, due to atmospheric refraction. Locations of the moon are shown at 3 and 6 hours, to show its actual position as given in the Nautical Almanac, and that its observed position must be interpolated between the given positions. From: Man is Not Lost; A Record of Two Hundred Years of Navigation with the Nautical Almanac, 1767-1967, p. 7.

John Harrison

John Harrison (1693-1776) was the English clockmaker who designed and built the first successful chronometers, clocks accurate enough to take to sea to measure longitude. He began his work in 1730 with the first sea trial in 1736. After 5 versions of his chronometer, he satisfied Britain's Board of Longitude government, earning some 23,000 pounds which he had recieved in increments as partial payments for various versions. The Board never did award him their full 20,000 pound prize.

Hadley's Quadrant

Though the first sextants were built by the 1790s, most navigators were still used a Hadley's Quadrant, or Octant, up into the middle of the 19th century. The quadrant's legs subtended a 45 degree angle, but with the double reflecting system enabled measurement of angles up to 90 degrees. The sextant could measure angles up to 120 degrees.

Page from 1767 Nautical Almanac

The Astronomer Royal, Nevil Maskelyne, is credited with checking and publishing calculated positions of the moon in the first British Nautical Almanac, in 1767. The Lunar Distances tables were fundamental to the finding of longitude at sea without a chronometer.

Nevil Maskelyne

Astronomer Royal Nevil Maskelyne is credited for checking and publishing calculated positions of the moon in the first British Nautical Almanac, in 1767. The Lunar Distances tables were fundamental to the finding of longitude at sea without a chronometer.

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