D.f. Loop Errors due to Heel

Extract

Yacht and other small-boat navigators must often wonder what error in a d.f. loop reading on a radiobeacon may be due to heel. The error is in fact quite small, the maximum for a 25° angle of heel being 2°.8 when the bearing is quadrantal to the boat's heading, i.e. when the relative bearing is 45°, 135°, 225° or 315°. When the relative bearing is 0, 90°, 180° or 270°, i.e. when the beacon is ahead or astern or abeam, the error is nil.

Table I gives corrections to the nearest ½ degree, to be applied to the relative bearing of a beacon for 15° and 25° of heel. It makes no difference whether the boat is heeled towards or away from the beacon.