Which type of vessel cannot impede the navigation of another vessel in a narrow channel?

In a narrow channel, certain navigation rules dictate the right of way to ensure safe passage and minimize the risk of collisions. A vessel that cannot impede the navigation of another typically refers to those that are either less able to maneuver or have specific restrictions based on their activity.

A vessel engaged in fishing, especially when using nets or gear that can extend into the channel, may restrict navigation for other vessels trying to pass. Similarly, sailing vessels, particularly those under sail alone, may have limitations in their ability to quickly change course or speed, which can hinder other vessels attempting to navigate through the channel.

Regarding vessels less than 20 meters in length, these are often considered to be less maneuverable or may have limitations in certain operational capabilities compared to larger vessels. They are generally treated under navigation rules with special considerations, such as the requirement to yield to larger vessels.

All types mentioned in the options—fishing vessels, sailing vessels, and smaller vessels—have rules that obligate them not to interfere with navigation in narrow channels, where passing can be challenging due to limited space. Therefore, the correct choice encompasses all these vessels, indicating that none should impede the navigation of others in such conditions.