What does SET refer to in terms of vessel navigation?

In the context of vessel navigation, SET refers to the direction a vessel is being pushed off course due to external forces, such as wind and current. This term is crucial for navigators as it helps them understand how external factors can influence a vessel's intended path. When a vessel is subject to environmental forces, SET indicates the deviation from the intended course. Knowing the SET enables navigators to adjust their steering or course accordingly to compensate for these external forces, ensuring safe and accurate navigation.

The other choices do not accurately capture the meaning of SET within vessel navigation. Understanding SET allows mariners to maintain their routes effectively, which is essential for safety and efficiency in maritime operations.