day shape

plural day shapes

1. nauticalAny of a set of simple geometric shapes that are hung from a mast and visually indicate the status of a vessel to other vessels.

   International Rule 25(e) requires the use of a cone, with point downward, as a day shape on all sailing vessels using machinery for propulsion while its sails are up.

   2006, Elbert S. Maloney, Chapman Piloting & Seamanship, page 145

   1 more example

   It would be a very simple matter to include with each keyboard, whether for night signal sets or day semaphores, a small vertical panel with miniature reproductions of the night lanterns in their proper color and position, and of the day shapes in proper order; these last to be made by illuminating a circular aperture containing a darkened glass disc with the figure of the shape in white.

   1903, Proceedings of the United States Naval Institute, volume 29, page 425