A snow or snaw is a sailing vessel. A type of brig

Brig

A brig is a sailing vessel with two square-rigged masts. During the Age of Sail, brigs were seen as fast and manoeuvrable and were used as both naval warships and merchant vessels. They were especially popular in the 18th and early 19th centuries...

 (snows are often-referred to as "snow-brigs"), snows were primarily used as merchant ships, but saw war service as well. The twin brigs Lawrence

USS Lawrence (1813)

The first USS Lawrence was one of two 493-ton Niagara-class brigs built at Erie, Pennsylvania, by Adam and Noah Brown under the supervision of Sailing Master Daniel Dobbins and Master Commandant Oliver Hazard Perry, for United States Navy service on the Great Lakes during the War of 1812.She was...

 and Niagara

USS Niagara (1813)

The US Brig Niagara or the Flagship Niagara, is a wooden-hulled brig that served as the relief flagship for Oliver Hazard Perry in the Battle of Lake Erie during the War of 1812. It is one of last remaining ships from the War of 1812. The Niagara is usually docked behind the Erie Maritime Museum in...

, American warships of the Battle of Lake Erie

Battle of Lake Erie

The Battle of Lake Erie, sometimes called the Battle of Put-in-Bay, was fought on 10 September 1813, in Lake Erie off the coast of Ohio during the War of 1812. Nine vessels of the United States Navy defeated and captured six vessels of Great Britain's Royal Navy...

, were both snows.

Snows carried square sail

Sail

A sail is any type of surface intended to move a vessel, vehicle or rotor by being placed in a wind—in essence a propulsion wing. Sails are used in sailing.-History of sails:...

s on both masts

Mast (sailing)

The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...

, but had a small trysail

Trysail

A trysail is small triangular or square fore-and-aft rigged sail hoisted in place of a larger sail when winds are very high....

 mast, sometimes called a snowmast, stepped immediately abaft the mainmast. This mast could carry a trysail with a boom

Boom (sailing)

In sailing, a boom is a spar , along the foot of a fore and aft rigged sail, that greatly improves control of the angle and shape of the sail. The primary action of the boom is to keep the foot of the sail flatter when the sail angle is away from the centerline of the boat. The boom also serves...

, with the luff

Luff

Luff or luffing may refer to:* Luffing, when a sailing sheet is eased so far past trim that airflow over the surface is disrupted* The leading edge of a sail...

 of the trysail hooped to it. Sometimes, instead of a trysail mast, snows carried a horse on the mainmast, with the luff of the trysail attached to it by rings.