What must be assessed to determine an appropriate safe speed?

Assessing the appropriate safe speed involves understanding various environmental and operational factors that can affect navigational safety. Evaluating visibility and traffic density is critical as these elements provide information about potential hazards and the ability to react to them.

Visibility directly impacts how well a vessel's crew can see other vessels, navigational aids, and potential hazards. When visibility is reduced, either due to fog, rain, or nighttime conditions, a slower speed may be necessary to maintain safe navigation. Similarly, traffic density gives insight into the number and behavior of nearby vessels. In situations where there are many vessels in proximity, maintaining a safe speed allows for safer maneuvering and increased stopping distance if required.

While considering the number of nearby vessels alone might seem relevant, it does not encompass the broader context provided by visibility and overall environmental conditions like weather. Factors such as engine size and the day's weather forecast can influence a vessel's capabilities or operational readiness but are not primary criteria for assessing safe speed. Instead, they can be secondary considerations that pertain to how a vessel operates rather than how speed should be determined based on the surrounding environment.