A pinnace is a small light sailboat that was very useful in the Sail Age and was used by merchant and war ships as an auxiliary vessel. It uses oars or sails as a propeller power.
The pinnace can used with different purposes depending of the use that the main ships has, for example when the principal ship was a war vessel, the pinnace was used as a scout the areas in order to avoid any obstacle, it was used to transport troops to land, transport mails and get water and food.
The pinnace use do not change a lot if the vessel is a regular ship, instead of transporting troops it was used for leaving passengers or persons to the shore.
This kind of vessel is now used for transportation of passengers between great ships that cannot fit at the port.
When the steam power appears some pinnaces were redesigned in order to be faster and transport its cargo faster and easier.