Chapter 10 Notes

Some of the terms used in BeeBee’s Status Report may require explanation.

VMG is Velocity Made Good, the boat’s speed directly towards the destination.
Speed Over Ground (SOG) is the speed of the boat over the surface of the earth, as measured, usually by a GPS. On BeeBee back in 1813, Starfix.
Boat Speed is the speed of the water past the hull. All of these variants of speed are needed to deal with current’s drift (speed) and set (heading), leeward sag (the distance the boat is blown off course by wind) and the point of sail that the boat is on, versus the wind’s true direction.

Please see see the Glossary for more on any term.

Impérieuse’s Course. Josh tells Thomas, “If you would please steer the same course you were this morning, my Lord, in Impérieuse: Two hundred and twenty degrees, nineteen and a half points, southeast.” He would know this from Bit-by-Bit’s radar which can track a vessel’s course accurately, but also from Impérieuse’s log entry for the noonday sighting.