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.
Anchor bend
While the knot can become jammed in some modern materials, it is usually easily untied after moderate loads; it can be made more resistant to jamming by taking an extra turn around the object--this will make for a 1-diameter longer span of the end to reach around the standing part to be tucked (although in a case of tying to a small shackle or link of a chain, this might not be possible). It is the accepted knot for attaching anchors (or more usually anchor chains) to warps. The knot is very similar to a round turn and two half hitches except that the first half hitch is passed under the turn. In many everyday uses, the finishing half-hitch need not be made; alternatively, one might seek surer security by tying off the end with a strangle knot to the standing part.