Drift is an involuntary movement away from the course due to wind, currents, and waves. Whether you’re a motorboat operator or a sailor, understanding drift is crucial because it complicates navigation.
Understanding Drift
To understand what drift is, you need to differentiate between the steered course and the actual course sailed:
The steered course is the direction shown by the compass – that is the direction in which the boat is pointing. Sailed course is the actual direction in which the boat is sailing – we almost always sail somewhat sideways. Drift is the angle between the steered course and the sailed course – in other words, how much we “drift.”
How Does Drift Occur?
Both above and below the water, the boat is affected by natural forces that push it in directions determined by the elements.
Drift from Wind Above the water, it’s primarily the wind that influences the direction. For example, a motorboat needs to account for the fact that the wind exerts pressure on the boat. Naturally, the stronger the wind, the more significant the impact. Especially in narrow passages and during harbor maneuvers, one must consider wind drift.
Drift from Current
Underwater, currents can significantly impact navigation. As a novice sailor, you’ll quickly discover that you can end up sailing sideways. This means that if you maintain a course based on the compass, you won’t arrive where you intended. To account for the current’s influence on the vessel, we work with a calculation called the current triangle.
It’s also important to mention that tides naturally contribute to drift because they can result in substantial water currents.
Drift from Waves
When large ships and smaller (fast) vessels pass us, we can experience a fair amount of drift. This is due to the waves pushing us. Of course, the same can happen when there are significant waves on the water. Therefore, pay attention to the direction of the waves and steer into them to compensate for the drift.
Drift can pose a real safety threat to boats and their crews, so it’s essential to understand how to predict and prevent it.