Page "Anchor" Paragraph 42

Permanent anchors come in a wide range of types and have no standard form.

A slab of rock with an iron staple in it to attach a chain to would serve the purpose, as would any dense object of appropriate weight ( e. g. an engine block ).

Modern moorings may be anchored by sand screws which look and act very much like oversized screws drilled into the seabed, or by barbed metal beams pounded in ( or even driven in with explosives ) like pilings, or a variety of other non-mass means of getting a grip on the bottom.

One method of building a mooring is to use three or more conventional anchors laid out with short lengths of chain attached to a swivel, so no matter which direction the vessel moves one or more anchors will be aligned to resist the force.