A vessel experiences this when leeway pushes it off its steered heading. It happens most often when sailing close-hauled or when a strong crosscurrent pushes against the hull. Navigators must calculate this lateral drift and steer slightly upwind or upcurrent to compensate and maintain the true track.
Heard on the job
We're starting to bag to leeward, so bring her head up a few degrees.
Also heard as
- sag