What Is a Mushroom Anchor? Definition, Meaning and Concept
An anchor is an object, usually made of metal, that is heavy and is used to prevent a ship from moving while it is in the water. A mushroom anchor is a specific type that is generally used in areas of water that have a fine sandy seafloor. As its name implies, a mushroom anchor is shaped into a mushroom shape, a design that allows the head to be buried in the sand or silt and thus anchor the boat. A mushroom anchor is a permanent anchor: it rarely moves and provides a mooring for the boat.
The mushroom anchor was first used in 1800 on a ship called the Pharos. Pharos was an 82-ton boat and the anchor weighed 1.5 tons. During this time, the ship was used as a temporary lighthouse while the real one was being built. Since then, anchors have been used on several different types of boats and range from something one person can lift to several tons.
In order for a mushroom anchor to be buried within the sand, a counterweight must be used. This is placed to force the stem to lie down before being buried. One of the benefits of a mushroom anchor is that it will generally continue to sink into the sand until you have moved the same mass as it. This means that it can displace a large amount of material and therefore provide a high level of holding power for the boat.
One reason a mushroom anchor can only be used as a permanent anchor is that it takes a relatively long time for it to fully embed. For this reason, it is usually first implemented during a quiet part of the year. One drawback to mushroom anchors is that they can only be used where there is sand or silt covering the seabed: they provide little holding force on rocky surfaces.
A mushroom anchor is just one type of permanent anchor - there are several others that can be used in different situations. For example, the deadweight anchor is much simpler in design and relies on being very heavy. The advantage of this is that it can be used on any type of seabed. An anchor bolt screws into the seafloor and provides a great amount of holding power. The downside is that they require access to the seafloor for installation, and therefore can only be used in exposed areas during low tides, unless a diver is available.