Author Topic: Course notation  (Read 2612 times)

Tango Whisky

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Course notation
« on: February 06, 2011, 03:01:22 pm »
In the logs courses are recorded in a notation I don't understand. A course might say N38?W while modern course notation is simply in degrees, either magnetic or true. Does anyone know how the older style relates to the compass? I'm guessing N38?W would mean 38 west of north, ie 322?, but not certain. Also would it have been recorded as true or magnetic?

Janet Jaguar

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Re: Course notation
« Reply #1 on: February 06, 2011, 08:18:05 pm »
First, we are not asked to record the columns showing course direction and distance covered.  The climatologists say it doesn't really help most of the time, and on the rare occasions they need it, they can see the original page.

Second, I'm a landlubber so I'm only quoting other references.

This from the Wiki article on Relative Bearing:
"In nautical navigation the relative bearing of an object is the clockwise angle in degrees from the heading of the vessel to a straight line drawn from the observation station on the vessel to the object. ... The measurement of relative bearings of other vessels and objects in movement is useful to the navigator in avoiding the danger of collision.
Example: The navigator on a ship observes a lighthouse when its relative bearing is 45o and again when it is 90o. he now knows that the distance from the ship to the lighthouse is equal to the distance travelled by the vessel between both observations.

This from the Wiki article on Bearing (navigation):
The US Army defines the bearing from Point A to Point B as the angle between: either a north, south, east, or west ray, whose origin is Point A and Ray AB, the ray whose origin is Point A and which contains Point B. The bearing consists of 2 characters and 1 number: first, the character representing the reference ray (N, or S); followed by the angle value; and finally the character representing the direction of the angle from the reference ray (E, or W). The angle value will always be less than 90 degrees. For example, if Point B is located exactly southeast of Point A, the bearing from Point A to Point B is E45S.

In the logs courses are recorded in a notation I don't understand. A course might say N38W while modern course notation is simply in degrees, either magnetic or true. Does anyone know how the older style relates to the compass? I'm guessing N38W would mean 38 west of north, ie 322o, but not certain. Also would it have been recorded as true or magnetic?
« Last Edit: October 13, 2012, 02:49:42 am by Janet Jaguar »