Special Marks    (Go To Top) 
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These yellow marks denote a special feature or area, such as a military zone, traffic separation scheme, pipelines, spoil areas or a scientific buoy. If these marks have a topmark (optional), it will be a yellow X. Lighted marks will have a yellow light. This buoy with the letter “B” marks the intersection of the Firth of Clyde Channel and Skelmorlie Channel. Both of these channels fall under Rule 9 (Narrow Channels) of the International Regulations for Preventing Collisions at Sea (1972). Skelmorlie Channel is a northbound channel for vessels with a draft of more than 15 meters (49 feet).    View Chart - Red Arrow #4  -- 270 KB

Safe Water Mark.  This example shows a Safe Water Mark identifying the middle of a channel and has a long flash.   This mark indicates navigable (safe) water on all sides of the mark.

Color:  Red and white vertical stripes
Shape: Sphere or buoy with a red spherical topmark
In the US, Safe Water Marks may not have a topmark.
Characteristic:  Letter(s)
Light:  White light, if lighted.  If the mark is used to identify an offshore approach to a channel or major port, it will have a light flashing the Morse Code (Mo) signal for the letter "A" (1 short flash followed by 1 long flash).
 
View Chart - Red Arrow #3  -- 270 KB

Isolated Danger Mark  This mark is placed near an isolated danger with navigable water all around.  It is infrequently used in the US.

Color:  Black and red horizontal bands
Topmark:  Two black spheres
Light:  If lighted they display a group of two white flashes every 10 seconds.

View Chart - Red Arrow #ID -- 180 KB

Range   (Go To Top)        Mouse over chart to enlarge, click on chart for large map.

A range is a pair of markers used to determine a line of position. In this example, if you line up the two markers, it will guide you down the middle of the entrance to Castletown Bearhaven (Castletownbere) harbor, Ireland.
     
View Chart - Red Arrows #R1 & #R2  -- 224 KB