Topmark (2)

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2-6-255

One or more relatively small objects of characteristic shape or colour (or both), placed on top of a navigation mark (or buoy) to identify it. (Figs. 65 and 66)

Note 1: A topmark may be

  • a. Simple
  • b. Composite, viz. made up of two or three individual topmarks.

Note 2: The following characteristic apparent shapes of topmarks are internationally recognised for the lateral system of marking (or buoyage):

  • Cone
  • Can
  • Sphere
  • Diamond
  • St. George's Cross
  • "T"
  • Broom

A broom topmark has the appearance of a circular broomhead and has two forms "Broom, point upwards" (in German, "mit Besen abwarts") and "Broom, point downwards" (in German, "mit Besen aufwarts").

Note 3: The following characteristic apparent shapes of topmarks are internationally recognised for the cardinal system of marking (or buoyage):

  • Two cones, point upwards
  • Two cones, point downwards
  • Two cones, point to point
  • Two cones, base to base

Note 4: Other forms (e.g. St. Andrew's Cross) are used, for example, as landfall marks.

Note 5: In the U.S.A. the word Daymark is often used for a topmark.

Ch2 Fig65.jpg

Ch2 Fig66.jpg




Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)

second

Time period

roll period

Transmissivity

acceleration due to gravity (m/s2)

South

ampere

International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM