Definition of "guard-boat" [guard-boat]

• A boat employed in guarding or watching, as one that is rowed about at night among ships of war at anchor to see that a good lookout is kept, or in time of war to prevent surprise, or one used for the enforcement of quarantine regulations. (noun)

The Century Dictionary (Public Domain)

• "Passing the guard-boat, we delivered our permit; before venturing into the open sea we repeated the Fatihah-prayer in honor of the"
• "The most ticklish part of the work had been approaching near enough in the guard-boat and putting the drogue overside after it had been attached to the line, but Field reported that no hail had come from the Estrella."
• "Two strong swimmers, their faces blackened, had slipped overside from the guard-boat and had swum unseen to the Estrella."