A yard is a spar on a mast from which sails are set. It may be constructed of timber or steel or from more modern materials like aluminium or carbon fibre. Although some types of fore and aft rigs have yards, the term is usually used to describe the horizontal spars used on square rigged sails. In addition, for some decades after square sails were generally dispensed with, some yards were retained for deploying wireless (radio) aerials and signal flags.
Parts of the yard
A view of Stavros S Niarchos‘s main-topgallant yard shortly after maintenance, clearly showing its various parts. On relatively “modern” late-nineteenth-century rigs like this, the quarters make up almost all of it. Click the picture for more details. Bunt The short section of the yard between the slings that attach it to the mast. Quarters The port and starboard quarters form the bulk of the yard, extending from the slings to the fittings for the lifts and braces. Yardarms The outermost tips of the yard: outboard from the attachments for the lifts.
Note that these terms refer to stretches of the same spar, not to separate component parts.
The yards are mounted on the mast in such a fashion as to allow free movement under the control of lifts and braces. The sail on this yard is “in its gear” – it is hanging below the yard but still folded up rather than spread to the wind.