What is a requirement related to the use of operational radar on a vessel?

The requirement to use operational radar on a vessel to obtain early warning of risk of collision is grounded in navigational safety principles. Radar serves as a vital tool in identifying other vessels, navigational hazards, and changes in the environment, especially when visibility is compromised. By enabling operators to detect potential collision threats well in advance, radar enhances situational awareness and supports effective decision-making to ensure safe navigation.

Utilizing radar primarily for collision avoidance aligns with best practices in maritime navigation. This functionality helps mariners assess their proximity to other vessels and take appropriate action to mitigate collision risks, reinforcing its critical role in maintaining safety at sea.

The other options do not align with standard operating practices. Using radar solely in low visibility conditions limits its effectiveness since navigators can also benefit from radar in clearer conditions to gather comprehensive situational awareness. Additionally, the assertion that radar must not be used for collision avoidance underscores a misunderstanding of its intended application. Finally, while regular testing of radar systems is essential for ensuring reliability, the suggestion that it can be turned off during daylight is contrary to the need for constant situational awareness, regardless of light conditions. Therefore, the correct understanding is that operational radar should continuously provide early warning of potential collisions.