Question 16 ONC04 - Mate of LT 500-1600 GRT

The Correct Answer is C. **Why option C is correct:** Option C, "navigating in or near an area of restricted visibility," correctly defines the scope of application for Rule 19 (Conduct of Vessels in Restricted Visibility) of the International Regulations for Preventing Collisions at Sea (COLREGs), which are adopted by the U.S. Inland Rules. Rule 35, concerning sound signals in restricted visibility, also applies when in or near such areas. These rules are designed to govern the conduct of all vessels (both international and inland) when navigating where visibility is reduced, regardless of whether the vessel itself is currently in dense fog or merely approaching it. The obligation to take precautions and use the appropriate rules begins when a vessel is operating where restricted visibility may be encountered. **Why the other options are incorrect:** * **A) only if they have operational radar:** This is incorrect. While Rule 19 specifically addresses the use of radar (taking an early warning of risk of collision), the general rules for restricted visibility (such as slowing down to a safe speed or making sound signals) apply to **all** vessels, including those without operational radar. * **B) in sight of one another in fog:** This is incorrect. If vessels are "in sight of one another," Rule 19 (Restricted Visibility) ceases to apply, and the rules governing vessels in sight of one another (Rules 4 through 18, depending on the situation) immediately take effect. The very definition of restricted visibility rules is that they apply when vessels are **not** in sight of one another. * **D) only if they are showing special purpose lights:** This is incorrect. The steering and sailing rules for restricted visibility (Rule 19) apply to all vessels, large or small, power-driven or sailing, whether they are showing special purpose lights (like lights for vessels constrained by their draft or fishing vessels) or standard running lights. The display of lights is separate from the application of the restricted visibility rules.