BBB Etymology - Square Meal

In the days of sail, British warships did not have the best of living conditions. A sailor's breakfast and lunch were sparse meals consisting of little more than bread and water. However, the third meal of the day included meat and was served on a square tray. Eating a substantial meal aboard a ship required a tray to carry it all because of the danger of sudden violent movement and the risk of spillage. Being square, the trays were more easily stacked and stored away when not in use and took up less valuable space than more conventional round ones would.