Sea anchor
Modern commercial sea anchors are usually made of cloth, shaped like a parachute or cone, and rigged so that the wider end leads and the narrower end trails. When deployed, this type of sea anchor floats just under the surface, and the water moving past the sea anchor keeps it filled. Some varieties are cylindrical, with an adjustable opening in the rear that allows the amount of braking to be adjusted when deployed.
History of the anchor
New Zealander Peter Smith in the early 2000s took elements of the Spade and other types, and developed unique solutions of his own, in order to design the "Rocna" anchor, a general purpose type which uses a concave fluke, a self-righting roll-bar, and setting skids.