47. INLAND ONLY You are navigating in a narrow channel and must remain in the channel for safe operation. Another vessel is crossing the channel ahead of you from your starboard and you doubt whether your vessel will pass safely. Which statement is TRUE?

Inland Rule 34(d) mandates sounding the danger signal when a vessel is in doubt about a safe passing. This applies when navigating in a narrow channel and another vessel is crossing ahead, creating uncertainty about safe passage; no other action is explicitly required.