You are aboard vessel "A" in a narrow channel and the pilot is approaching vessel "B" as shown in illustration D037RR below. Which of the following is the reason he has not previously changed course to the starboard side of the channel?

Correct Answer: Option A — to avoid the effects of bank cushion and bank suction

Bank cushion occurs when the bow wave reflects off the bank, pushing the bow away, while bank suction pulls the stern toward the bank. Pilots remain in mid-channel to avoid these hydrodynamic interactions, which can cause the vessel to sheer uncontrollably and potentially ground in narrow, restricted waterways.