Traverse board
Encyclopedia
Dead reckoning
In navigation, dead reckoning is the process of calculating one's current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course...
navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
to easily record the speeds and directions sailed during a watch. Even an illiterate crew member could use the traverse board.
The traverse board is a simple wooden board with peg-holes and attached pegs. It is dividend into two parts.
The top part is for recording direction sail
Sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...
ed. It has a representation of the compass rose
Compass rose
A compass rose, sometimes called a windrose, is a figure on a compass, map, nautical chart or monument used to display the orientation of the cardinal directions — North, East, South and West - and their intermediate points. It is also the term for the graduated markings found on the traditional...
with its 32 compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...
points, just as it would have been shown on the face of the ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
's compass. Eight concentric rings are inscribed on the compass rose, each with one peg hole at each point of the compass. Eight pegs are attached to the center of the compass rose with strings.
The bottom part is for recording speed. It has 4 rows of holes. Each column represents a certain speed, measured in knots. Eight pegs are attached to this part of the board.
Each half-hour during the watch, a crew member would insert a peg in the top portion of the board to represent the heading
Heading
Heading can refer to:*Heading , a process which incorporates the extruding and upsetting processes*Headline, text at the top of a newspaper article*The direction a person or vehicle is facing, usually similar to its course...
sail
Sail
A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...
ed during that half-hour, just as it is shown on the ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
's compass
Compass
A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...
. The innermost ring of peg-holes is used for the first half-hour, the second for the second half-hour, and so on until all 8 rings were use.
Each hour during the watch, a crew member would insert a peg in the bottom portion of the board to represent the speed
Speed
In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as...
sailed during the hour. The speed would have been measured using a knot log. If the speed for the first hour of the watch were 10½ knots, the crew member would count over 10 holes in the first row and place one peg, then place another peg in the column marked "1/2". In the second hour of the watch, the crew member would use the second row of pegs, and so on until all 4 rows were used.
At the end of the watch, the navigator would collect the information about the speeds and directions sailed during the watch, clear the pegs from the board, and use the information to figure the vessel's dead reckoning
Dead reckoning
In navigation, dead reckoning is the process of calculating one's current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course...
track. Meanwhile, the helm
Helmsman
A helmsman is a person who steers a ship, sailboat, submarine, or other type of maritime vessel. On small vessels, particularly privately-owned noncommercial vessels, the functions of skipper and helmsman may be combined in one person. On larger vessels, there is a separate officer of the watch,...
of the new watch would begin recording the new sailing heading
Heading
Heading can refer to:*Heading , a process which incorporates the extruding and upsetting processes*Headline, text at the top of a newspaper article*The direction a person or vehicle is facing, usually similar to its course...
s and speed
Speed
In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as...
s on the traverse board.
External links
- The Pilgrims & Plymouth Colony:1620 -- Navigation: The Traverse Board by Duane A. Cline—line drawing of traverse board