Plane sailing

Plane Sailing and Passage Planning Traverse Tables Courses

For centuries, navigators thumbed through traverse tables using their course and distance sailed to find their latitude and longitude. They called this their 'daily work' (see Figure 18.1). This is 'plane' or 'raverse' sailing, and is based on the angles of a plane, right-angled triangle.

Back in the 14th century someone, knowing that trigonometry is not a seaman's strongest suit, worked out all the possible answers to all possible courses and distances and then published the answers as the world's first traverse tables. Nowadays you may find a copy in a forgotten corner of a nautical bookshop, but a cheap scientific calculator with trig functions lets you find the answers for yourself. It looks daunting when laid out on paper complete with explanations, but it is easier than jumping between columns in a book of traverse tables.

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