Your vessel must stay within a narrow channel to be navigated safely. Another vessel is crossing your course from starboard to port. You do NOT think she will pass safely. You __________.

In this scenario, the correct action to take when you believe another vessel will not pass safely is to sound the danger signal. This action is crucial for alerting the other vessel that a potential collision could occur. According to the Rules of the Road, sounding a danger signal—a series of five short blasts on the whistle—indicates that you are concerned about the intentions of the other vessel and that you believe the situation is unsafe.

Taking this measure can help clarify your position and intentions, prompting the other vessel to take corrective action if needed. It is part of maintaining safety in navigation, especially in confined waters like a narrow channel, where the maneuverability of vessels may be limited.

Other options do not appropriately address the concerns of the situation. While turning to starboard may sometimes be a necessary action, it should not be your first response without confirming the other vessel's actions. Continuing at full speed would disregard the apparent danger and could lead to a collision. Additionally, taking no action could result in an accident if the risk is valid, as it neglects the responsibility of ensuring navigational safety.