Symmedian Point

Shift a celestial navigation LOP triangular plot center slightly toward the short side (sides) for an improved probable position (symmedian point)

http://en.wikipedia.org/wiki/Symmedian

Horizontal Sextant Angle Plot Made Easy

Make short work of plotting horizontal sextant angles by determining the arc radius using a chart plotting board, radar plotting sheet, or the simple formula (0.5 mark A to mark B)/ sin(horizontal sextant angle) = radius. Once the radius is known then a chart plot is performed by arcing the radius off navigation marks A & B then plot the arc of position from the radius point intersection to determine an estimated position. The chart plotting board image above shows a radius solution for a horizontal sextant angle of 45° and a distance between marks A and B of 16.6 nautical miles.