Final answer:
When overtaking another vessel on the port side in a narrow channel, signal with two short horn blasts as per COLREGs Rule 34. Await a responsive two short blasts from the overtaken vessel to confirm the safe passing maneuver.
Step-by-step explanation:
When attempting to overtake another vessel in a narrow channel on the port side, international maritime signaling protocols must be adhered to in order to communicate your intentions clearly and prevent collisions. The International Regulations for Preventing Collisions at Sea (COLREGs), specifically Rule 34, dictates the proper use of sound signals in such scenarios. If your vessel intends to overtake on the port side, it is advised that you sound two short blasts (denoted as two short horn honks) to indicate this intention. The vessel being overtaken should respond with two short blasts if the maneuver is agreed upon and they are able to permit safe passing. However, the action should only be taken if the vessel being overtaken responds positively; without confirmation, it remains the responsibility of the overtaking vessel to avoid a collision, ensuring safety on both vessels.
It is crucial that all maritime operators understand and adhere to these signaling protocols to maintain safety at sea. The COLREGs are enforced internationally and serve as more than 100 words standard guideline to ensure that mariners can communicate intentions and navigate safely, especially in situations where visual signals might not be as effective, such as the poor visibility conditions described in the excerpts provided.