Pinnace

A pinnace is a light boat, propelled by sails or oars, previously used as a "tender" for guiding merchant and war vessels. In modern parlance, pinnace has come to mean a boat linked with some kind of larger vessel, that doesn't fit under the launch or lifeboat definitions. In all-purpose, the pinnace had sails, and would be used to ferry messages between ships of the line, visit harbors ahead of the fleet with messages of state, pick up mail, etc.