Sailors typically used 30-minute or one-hour sand glasses to track watch duties and measure the passage of time. Combined with a chip log the sand glass allowed mariners to calculate how far they had travelled in a set time, a remarkably effective method in an era without precise timekeeping.

It usually consisted of a polished brass frame with a wooden handle, used to measure angles greater than 180 degrees. At sea it was used for finding longitude. Invented by the German astronomer Tobias Mayer in 1752, its use was more widespread in the French than in the British navy.

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Enacted because the captains and crews of merchant vessels often refused to fight off pirates. Failing to resist would result in the commander being excluded from further commands or imprisonment. Sailors were also required to fight. Failure to do so resulted in a loss of wages and imprisonment.

Although widely used from about 1460, it was eventually superseded by the more precise octant in the early 18th century, which was in turn replaced by the sextant in the middle of the same century.

It is thought that the pelorus came into use before the compass, in particular by the Polynesians. Nowadays, this tool is used on modern boats to measure the distance between one boat and another.