dogvane

A small vane of bunting, feathers, or other light material, fastened to the end of a short staff and placed on the weather gunwale of a sailing ship to assist the helmsman to judge the direction of the wind.

she had an ugly knack of stopping, and swinging one leg all manner of ways, like a dogvane in a calm.

Nor was any mariner surprised when, after inspecting the compass, and then the dog-vane, and then ascertaining the precise bearing of the odor as nearly as possible, Ahab rapidly ordered the ship’s course to be slightly altered, and the sail to be shortened.

A cockade worn on a hat (worn in the British Navy in the 18th and 19th centuries)