As the person in charge of a stand-on vessel in a crossing situation, what should you do if the other vessel is 1.5 miles to port and risk of collision exists?

In a crossing situation where you are the stand-on vessel and another vessel is approaching from a position that poses a risk of collision, the appropriate course of action is to take avoiding action only after allowing the give-way vessel an opportunity to maneuver. As the stand-on vessel, you have an obligation to maintain your course and speed, but when it is clear that a collision may occur, you must be prepared to act.

Allowing the give-way vessel some time to respond respects the requirements of the "Rules of the Road," which emphasize communication and predictability at sea. It is essential that the give-way vessel has the chance to take measures to avoid the situation before you alter your own course. This promotes safe navigation and cooperation among vessels.

The other choices may not facilitate safe navigation as effectively. For instance, taking avoiding action immediately could confuse the other vessel and exacerbate the situation. Signaling may not effectively address the immediate danger without first assessing the other vessel's actions. Drastically changing course can lead to unpredictable movements that might create further risks. Therefore, the most prudent and rule-abiding response is to initially maintain your course while observing the actions of the other vessel.