Hull-down
（重定向自Hull up）
![Leclerc tank in a hull-down position. Note the observation periscope which would allow the commander to observe in turret-down position.](/Images/godic/202501/18/Leclerc-openphotonet_PICT59953217.JPG")
![Front view of a tank in turret-down and hull-down positions. A vehicle in a position with a background is more difficult to observe than one which is sky-lined.](/Images/godic/202501/18/Sky-lined_tank3217.png")
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![Swedish Stridsvagn 103 was designed to be nearly invisible in a hull-down position.](/Images/godic/202501/18/Strv_103c_a3218.jpg")
In sailing and warfare, hull-down means that the upper part of a vessel or vehicle is visible, but the main, lower body (hull) is not; the opposite term hull-up means that all of the body is visible. The terms originated with sailing and naval warfare in which the curvature of the earth causes an approaching vessel to be first visible "sails-up." Beginning in the 20th century, hull-down has also been used in armoured warfare.