What is the minimum visibility of an all-round white light on an inconspicuous, partly submerged vessel or object being towed?

The minimum visibility of an all-round white light on an inconspicuous, partly submerged vessel or object being towed is indeed 2 nautical miles. This requirement is specified in the COLREGs, particularly in the rules that govern the lights and shapes that vessels must display for proper identification and safety at sea.

The reasoning for the 2 nautical mile visibility stems from the need to ensure that vessels nearby can detect such partially submerged or inconspicuous objects, which may otherwise pose a navigational hazard. This visibility range allows other vessels to take appropriate action to avoid collisions.

In terms of the context of other visibility requirements for different types of vessels and lights, having a consistent standard helps maintain safety across a variety of boating situations. It's important for sailors and officers to understand these regulations in order to navigate safely and effectively in different waters.