Chart Navigation & Plotting · Piloting — Horizontal Danger Angle
Two charted objects are used to set a horizontal danger angle measured with a sextant. To stay outside a charted danger, the measured horizontal angle between the two objects must be kept:
- AExactly at the danger angle
- BGreater than the danger angle
- CLess than the danger angle, since a larger angle means you are too close✓ Correct
- DAt zero
Explanation
The horizontal danger angle is the sextant angle subtended by two charted objects from a circle passing through them and tangent to the danger. The nearer you are, the larger the subtended angle; so to remain outside the danger circle you keep the measured horizontal angle LESS than the danger angle.
Authority: Bowditch (Pub. No. 9), Danger Angles
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