Neither power-driven vessel A nor power-driven vessel B gives way or stands on in a head-on encounter. Therefore, some communication is needed between vessels A and B.
The most common response in a head-on meeting between power-driven vessels is to signal an intention to pass port-to-port. This action is initiated by one of the vessels sounding one short blast.
In short, vessel A must blow one short blast, indicating its intention to pass port-to-port, and then alters its course to starboard. Vessel B must return one short blast—to indicate agreement and understanding—and alter its course to starboard, thereby, leaving room on each vessel's port side for passing.
If it is not possible to pass port-to-port due to an obstruction or shoreline, a starboard-to-starboard pass should be signaled with two short blasts.
In short, vessel A must blow two short blasts, indicating its intention to pass starboard-to-starboard, and alter its course to port. Vessel B must return two short blasts to indicate agreement and understanding and alter its course to port, thereby, leaving room on each vessel's starboard side for passing.
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