The front lead has its apex pointing up and the rear or back lead has its apex pointing down. Leading lights/beacons usually display a triangle shape. There are some other aids to navigation that you need to be aware of. North cardinal marks show there is safe water to the North of the mark. To remember each type, think of a compass face with the numbers of a clock marked on it beside each direction (North, East, South and West). a feature in a channel (for example, a bend, junction or the end of a shoal).Ĭardinal marks have black and yellow bands with black double cones on top showing the different compass direction that identifies the safest and deepest water to travel in.Īt night, each type of cardinal mark has a flashing white light with different groupings of flashes (continuous, or groups of 3, 6 or 9).where to find the deepest water in an area.keep starboard (green) marks on your port-hand side (left).Ĭardinal marks show where the deepest and safest water is by using a compass.keep port (red) marks on your starboard-hand side (right).When travelling downstream or towards the sea: keep starboard (green) marks on your starboard-hand side (right).keep port (red) marks on your port-hand side (left).When travelling upstream or away from the sea: When there is a single lateral mark, the safe side to pass depends on the direction of travel (or buoyage).The direction of buoyage is shown on charts by the symbol: When a port and starboard lateral mark are opposite each other, travel between them.