How do cardinal buoys show the safest side for passing a navigational hazard?

Cardinal buoys are used in coastal navigation to indicate the deepest water in an area or the safest side to pass a navigational hazard.1

These buoys are identified by their black and yellow horizontal bands and a distinctive "topmark" consisting of two black cones. The configuration of these cones corresponds to the four cardinal points of the compass, signaling the side on which the safest navigable water lies:1

• North: Both cones point upward.
• South: Both cones point downward.
• East: The cones are arranged base-to-base.
• West: The cones are arranged point-to-point.

By observing the topmark, a navigator can determine the direction of the safest water relative to the hazard.1