An isolated danger mark is erected on, or moored on or above, an isolated danger of limited extent which has navigable water all around it. The extent of the surrounding navigable water is immaterial; such a mark can, for example, indicate either a shoal which is well offshore or an islet separated by a narrow channel from the coast.

Position

On a chart, the position of a danger is the center of the symbol or sounding indicating that danger; an isolated danger buoy may therefore be slightly displaced from its geographic position to avoid overprinting the two symbols. The smaller the scale, the greater this offset will be. At very large scales the symbol may be correctly charted.

Topmark

A black double-sphere topmark is, by day, the most important feature of an isolated danger mark. Whenever practicable, this topmark will be carried with the spheres as large as possible, disposed vertically, and clearly separated.

Color

Black with one or more red horizontal bands are the colors used for isolated danger marks.

Shape

The shape of an isolated danger mark is not significant, but a buoy will be a pillar or a spar.

Light

When lighted, a white flashing light showing a group of two flashes is used to denote an isolated danger mark. As a memory aid, associate two flashes with two balls in the topmark.

• Long range identification and tracking-LRIT - 2010-01-12 - 10:30:50
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• Limitations Of Sound Signals - 2009-04-02 - 03:06:28
• Types Of Sound Signals - 2009-04-02 - 02:55:51
• Description Of The U.S. Aids to Navigation System - 2009-04-02 - 02:31:02
• Chart Symbols And Abbreviations - 2009-04-02 - 02:13:58
• Buoyage System - IALA New Dangers - 2009-04-02 - 02:00:57
• Buoyage System - IALA Special Marks - 2009-04-02 - 01:47:49
• Buoyage System - IALA Safe Water Marks - 2009-04-02 - 01:31:10

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