Which rule discusses the actions of vessels constrained by their draft?

The correct choice relates to Rule 18, which specifically addresses the actions of vessels that are constrained by their draft. According to this rule, vessels that are deeply laden and have limited maneuverability must be afforded particular consideration in terms of right-of-way and navigational priority.

Vessels constrained by their draft are typically large vessels such as tankers or bulk carriers that cannot navigate freely due to their depth in water, which affects their ability to change direction or speed effectively. Rule 18 emphasizes that other vessels must keep clear of these constrained vessels to prevent collisions and ensure safe navigation.

Overall, this rule is critical for maintaining safety on the water, as it delineates the responsibilities of various types of vessels when navigating in proximity to one another, particularly when it comes to those vessels that are at a disadvantage due to their physical characteristics.