Compass dial

Conditions were variable for the closing clay of the Winter Series, with the CYCA's leading female compelitors out in force for some fine racing in a 4-5 knot westerly breeze that flicked either side of west on the compass dial and dropped to 1.5 knots as the back markers crossed the start line.

Other sixteenth-century devices used an arm above the compass dial to cast a shadow representing the true N/S direction on the dial, but the principle was the same.

When I come up to this tree my direction and cross reference heading will marry up to exactly what is indicated on the compass dials. A tree will make sense of this trick.