A "tall ship" is not a strictly defined type of sailing craft. For most people, the term brings to mind the largest and most majestic of the old style, square-rigged sailing vessels. Almost always we will think of a ship with three or more masts and many sails.

A tall ship can actually be one of any number of differently rigged sailing vessels. It could be a schooner, brigatine, barquentine, brig, ketch, sloop or a full-rigged sailing ship. The actual rig of a specific sailing vessel know as a tall ship is dependent on the number and cut of the sails as well as their alignment.

For the purpose of classification and race ratings, the International Sail Training Association divides tall ships into three classes and several sub-classes.

Class A: All vessels more than 160 feet in length, regardless of rig and all square-rigged vessels more than 120 feet in length. Square rigged vessels include ships, barques, barquentines, brigs and brigatines, but not square topsail schooners.

Class A Division II: All square-rigged vessels less than 120 feet in length.

Class B: Fore-and-aft rigged vessels between 100 and 160 feet in length.

Class C: All other fore-and-aft rigged vessels at least 30 feet long at the waterline.

Because of the common use of the phrase Tall Ships, most people do not know that it is a registered trademark. The trademark is owned by ASTA and should be noted that way when it is used in conjunction with the organization of sailing events and races and related commercial activities such as the Tall Ships Challenge^®.