In maritime navigation, what must be considered when calculating actual arrival time?

The aspect that must be considered when calculating actual arrival time is the surge rate. Surge rate refers to the speed at which a vessel can adjust its speed and direction in response to various influences such as weather conditions, currents, and navigational hazards. It is crucial to account for this factor because it directly impacts the vessel's overall travel time, especially in dynamic marine environments where conditions can change unexpectedly.

Considering surge rate allows navigators to make more accurate estimates of arrival times by understanding how quickly the vessel can effectively respond to changes in the surrounding environment. This is particularly important in ensuring safe navigation and maintaining schedules, especially in situations where timing is critical, such as docking or meeting other vessels.

The other factors influence navigation but do not directly address the immediate adjustment and calculation of arrival time in the same way as surge rate does. Weather changes can affect overall conditions, fuel type impacts operational efficiency, and equipment efficiency relates to the vessel's performance over time, but these are broader considerations. Surge rate focuses specifically on the dynamic element of navigation that affects real-time calculations of arrival.