What is the primary consideration when determining safe speed?

The primary consideration when determining safe speed is the position of other vessels and environmental conditions. This is paramount because establishing a safe speed allows the mariner to take necessary actions to avoid collisions. The navigational environment plays a crucial role in assessing potential risks; factors such as visibility, weather conditions, sea state, and traffic density must all be considered when setting a vessel's speed.

For example, in reduced visibility due to fog or heavy rain, a vessel may need to reduce speed significantly to ensure that the crew can react in time to any obstacles or other vessels. Similarly, in congested waters, being aware of the position of other vessels is essential to maneuver safely and avoid potential collisions. This approach aligns with COLREGs Rule 6, which emphasizes the need for vessels to proceed at a safe speed at all times to be able to take proper and effective action to avoid collisions.

While the size of the vessel, fuel consumption, and the speed of opposing vessels can also influence operational decisions, they are secondary to the immediate need for situational awareness and collision avoidance.