from the National Maritime Museum
It was well that he did, for with the rising of the moon the wind increased, blowing straight into her round, foolish face and across the growing swell. By the time he came on deck Mowett had already takin in the lower studdingsail, and as the night wore on more and more canvas came off until she was under little more than close-reefed fore and main topsails, reefed courses and trysails, yet each time the reefer of the watch cast the log he reported with mounting glee, “six and a half knots, if you please, sir. — Seven knots two fathoms. –Almost eight knots. –Eight knots and three fathoms. –Nine knots. –Ten knots! Oh sir, she’d doing ten knots.”
The Reverse of the Medal, Patrick O’Brian.
Navigation was the critical function required of a ship’s captain and master during the Age of Sail. It made little difference how fast your crew could make sail or serve the great guns if you didn’t know where you were going.
We’ll cover calculating northing and easting in the future. In the last story we looked a how casting the lead allowed a ship to be sure it was in water of a safe depth. In this story we’ll answer the question “How fast am I going?”