a small vessel of around 20 tuns, generally having two square-rigged masts. Pinnaces were small, fast, and maneuverable and sometimes carried oars. They were frequently used as message boats within fleets and were also highly regarded by the English for scouting coastal waters. Some small, undecked pinnaces were technically boats, for they could be taken aboard larger vessels.
A pinnace is a light boat, propelled by sails or oars, formerly used as a "tender" for guiding merchant and war vessels. In modern parlance, pinnace has come to mean a boat associated with some kind of larger vessel, that doesn't fit under the launch or lifeboat definitions. In general, 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.