# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Horizontal Angle and the Hand Bearing Compass
From: Greg Rudzinski
Date: 2011 Jun 3, 13:54 -0700

Try taking a horizontal angle using a hand bearing compass the next time out sailing. This only requires taking the difference between two bearings and plotting the arc of position. This adds a third line of position to the pair of magnetic bearings and will act as a deviation check. My favorite way to plot a horizontal angle is to take half the distance between mark A and mark B then divide by the SIN of the angle between mark A and mark B. The result is the radius of the circle which passes through the observer and marks A & B. Plot the circle by first marking off the circle center using the radius distance arced off marks A & B. From the circle center then trace the cirlce that will pass through mark A & B and the observer. I find this technique very quick using only a divider compass and pocket trig calculator.

Greg Rudzinski
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