What is the minimum visibility of a towing light on a vessel of 20m in length?

The minimum visibility of a towing light for a vessel that is 20 meters in length is indeed 1 nautical mile. According to the International Regulations for Preventing Collisions at Sea (COLREGs), specifically Rule 24 regarding the lights and shapes for towing vessels, it stipulates that vessels engaged in towing that are less than 50 meters in length must show their towing light, which should be visible at a minimum distance of 1 nautical mile.

This regulation is designed to ensure that other vessels in the vicinity can easily identify a towing vessel and take appropriate actions to prevent collisions, especially in conditions of reduced visibility. The specification of visibility for light signals is critical for maintaining safety at sea, ensuring that the operators of nearby vessels have sufficient warning to navigate safely around a towing operation.

The other visibility distances listed exceed the minimum requirement established for a vessel of this size, which is specifically addressed in the regulations. It is essential for mariners to be familiar with such regulations to ensure compliance and the proper operation of their vessels in different scenarios.