You are ascending a river and exchanging navigational information via radiotelephone with a descending vessel. If the descending vessel advises you to "watch for the set" above point X, what would you expect to encounter above point X?

Correct Answer: Option B — A sideways movement of your vessel

In river piloting, "set" refers to the horizontal drift or sideways movement imparted to a vessel by cross-currents or river dynamics. Mariners must anticipate this hydraulic force near bends, confluences, or obstructions to maintain safe navigation and avoid grounding.