Top mark

Double cones as a top sign of a cardinal barrel off Falmouth , England: When visibility is poor, top signs are often easier to make out than color markings

A top mark is a mark that is attached to the top of a sea ​​mark . A top mark usually has the shape of a solid of revolution or at least a doubly symmetrical body so that it can be recognized in the same way from all directions.

Top marks usually indicate a special meaning of the sea mark (e.g. designation of a single point of danger); they are mainly used for the side designation of fairways ( lateral system ) as well as for the direction designation of danger spots ( cardinal system ). Top marks can also generally support the differentiation of sea marks if only some of them have top marks.

Forms of top marks:

• Cylinder (denotes the incoming left side of a fairway, see lateral system )
• Cone ( cone pointing upwards: denotes the right-hand side of a fairway, see lateral system )
• Double cone (cones directed upwards or downwards in different combinations: direction designation in the cardinal system )
• Double ball (single danger point)
• Sphere ( middle fairway sign )
• Lying cross ( special characters )
• Standing cross ( emergency wreck buoy )