Navigation tools (traverse board, knot log and hour glass)
Acquired: 21 March, 2008
Acquired from: The Netherlands
The hour glass and knot log are used in combination. The knot log's sinker is thrown in the sea at regular intervals, while the hour glass measures the time. The length of the rope at the end of the interval measures the speed of the ship. The traverse board is a tool used to record this data on.