INTERNATIONAL ONLY You are in sight of another vessel in a crossing situation, and the other vessel sounds one short blast. You are going to hold course and speed. You should __________.

Correct Answer: Option A — sound no whistle signal

COLREG Rule 34(a) mandates that maneuvering whistle signals are only sounded when vessels are in the act of altering course. Since the other vessel is crossing and you are holding course and speed, no whistle signal is required or permitted.