Which of the following is NOT a characteristic of marks in the maritime buoyage system?

In the maritime buoyage system, the characteristics of marks are essential for safe navigation and aid in identifying different buoys and beacons. Each characteristic plays a vital role in the overall function and purpose of these navigational aids.

The shape of the marks is important as it provides immediate visual recognition, helping mariners distinguish between the types of buoys (e.g., lateral marks, safe water marks). Colour is also a critical feature, as different colours signify various meanings. For instance, red typically indicates a port side mark, while green signifies a starboard side mark.

Topmarks, which are additional symbols or shapes placed on top of a buoy, assist day navigation by providing additional visual identification aids, further enhancing the overall effectiveness of the buoyage system.

Size, however, is not a defining characteristic of the marks in the international buoyage system. While the dimensions of a buoy can vary, they are not standardized as defining characteristics in the buoyage system. The critical features that communicate information about the buoy's function and purpose revolve around its shape, colour, and any topmarks it may have during the day. Thus, size is the characteristic that does not fit within the essential defining traits of marks used in the maritime buoyage system.