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Types of Anchors And How They Work

Anchors are nautical or marine equipment widely used to prevent the movements of ships and boats in the water. In general, anchors use two main mechanisms to hold the ship; either they use their weight to hold the structure in place, or they clamp onto the bed of the water body. Some other anchors may use both mechanisms at the same time.

There are various kinds of anchors already used for ships and boats. In this article, we are going to learn about some of the most widespread anchors, in addition to some other useful information about anchoring.

How Does An Anchor Hold A Boat?

The very first force that prevents the anchored ship from moving is the weight of the chain and anchor on the bottom of the sea. The wind can push the boat away from its original place a bit, but anchors are meant to maintain its position.

In addition to using the weight to control the boat, most anchors have flukes that have been designed to dig into the ground in the case of movement. When wind and waves push the boat and exert pressure on the chain, the anchor digs deeper into the sand.

To lift the anchor, the boat should be just above it. You pull the chain on the boat, and the boat moves until it reaches above the anchor, getting you ready to lift it out.

Types of Anchors

Anchors have advanced dramatically over the previous decades. There is a variety of anchors available today for different scenarios. From more modern anchors including scoop anchors to more traditional ones like fisherman anchors, many options are ahead of you if you tend to buy an anchor for your boat.

You can choose the proper anchor for your boat according to the type of seabed in your area, the weight of your boat, and the material used in your anchor. Now, let us review some of the most common types of anchors.

Fluke Anchor

  • Great for mud or sand bottom
  • Stores very easily
  • Can be used for small and large vessels
  • Not great for rocky bottom
  • Pointy edges could be a safety hazard

Most popular in boats under 25 feet

Also referred to as Danforth or Lightweight anchors, fluke anchors are the most common type of anchors. They come with wide and flat flukes made from strong steel. To keep your boat firmly in place, the flukes at the end of these anchors dig themselves into the seabed. The slight pulling force of the moving boat makes the anchor dig further into the seabed.

Most boat owners often pick fluke anchors because they are lightweight and easy to handle, hence being appropriate for smaller boats. They also stow flat, leading to incredibly easy storage in small boats. Do not forget to store your anchors properly when you do not need them, as their sharp edges may harm you once kicked or stepped on accidentally.

You should check your boat length when planning to buy a fluke anchor. You need to purchase heavier fluke anchors if your boat is lengthy. Boats ranging from 8 to 49 feet in length may need fluke anchors from 4 to 44 pounds. Some boat lengths may be compatible with more than one size of anchors. If you have a long boat or tend to use it on aggressive waters, you need to acquire heavier anchors.

Delta/Plow Anchor

  • Great for almost any bottom
  • Fits well on bow anchor rollers
  • Struggles in very rocky bottoms
  • Hard to stow
  • Heavy

Most popular in boats 25-50 feet

Plow anchors are also among the highly widespread anchors used. They are usually recognized by their resemblance to a large shovel or scoop. Plow anchors are able to hold the boats in more seabed types compared with the fluke anchors.

Plow anchors are also used for large boats. They can easily adapt the situation of the boat to the direction of the wind. These anchors are more difficult to store than fluke anchors. Plow anchors can gradually “plow” themselves into the seabed, burying themselves there to hold the boat tightly in place.

These anchors are designed to be able to swivel. This helps them stick to the seabed strictly. This can be an issue in the case of fluke anchors, as they are not designed to swivel like plow anchors.

Choosing the proper plow anchors depends on the length of your boat, just like fluke anchors. Boats ranging from 22 to 65 feet in length may require plow anchors ranging from 26 to 60 pounds. Normally, plow anchors are heavier than fluke anchors, giving them more holding power despite being more difficult to operate.

Grapnel Anchor

  • Great in rocks
  • Can be used for a verity of different boat sizes
  • Not so great in mud or sand
  • Can be hard to retrieve
  • Can dislodge if there is a big wind shift

Can be used for almost any boat

Either in fixed or folding forms, grapnel anchors do not have the ability to hinge or swivel. They use their weight to maintain the boats in their positions, just like plow anchors. These anchors can hold boats as large as the boats that plow anchors normally hold, though they are mostly used for smaller boats. The main disadvantage of grapnel anchors is that their upright flukes are prone to tangling with the anchor line, and pulling the anchor out can be challenging.

Just like plow anchors, grapnel anchors are also able to hold onto more types of seabed than the fluke anchors such as rocks. Despite that, they cannot hold onto seabeds such as sand or mud as strongly as plow anchors do. It is difficult to handle and store grapnel anchors as they are heavy, just like plow anchors, unless they are in a folding style.

While plow anchors are all heavy, there are some lighter variations of grapnel anchors which are more appropriate for smaller boats. For boats that are 17 to 60 feet in length, there are grapnel anchors weighing from 25 to 66 pounds. For heavier boats or more volatile water conditions, you better opt for heavier grapnel anchors.

Claw Anchor

  • Great for rock and soft mud
  • Fits well on bow anchor rollers
  • Not good for hard mud and clay

Best for boats around 21-40 feet long

Since claw anchors are set easily and deal with most seabeds, they are among common boat anchors. They can cling to rocks easily, making them more ideal than previous anchors in this regard. Claw anchors are also known as Bruce anchors, as they have a wide three-claw design.

Despite clinging firmly to rocks and seabed structures, claw anchors are more difficult to set and hold. This forces you to choose a heavier claw anchor compared with previous anchor options. Also, claw anchors are hard to stow, similar to plow and grapnel anchors.

In the case of price, claw anchors are more affordable than other anchors. Thus, it is a more popular option among recreational boat owners.

For boats from 13 to 60 feet in length, you can purchase claw anchors from 6 to 66 pounds. It is obvious that you need heavier anchors for lengthier boats.

Scoop Anchor

  • Work for all seabed types
  • Reset themselves very easily due to the roll bar
  • They’re my favorite anchor type
  • Can be hard to store on deck if you don’t have an anchor roller
  • Expensive
  • Not the best option for rocky seabeds

Can be used for almost any boat

The term “scoop” actually refers to the new generation of modern anchor designs, including the Rocna, Spade, and Manson anchors. The popularity of these designs is soaring as they can work in many seabed types and have high holding power.

Scoop anchors can be set and reset more easily than other anchors. This helps you pick a lighter scoop anchor, as it can be set efficiently. Despite that, these anchors are more difficult to store on the deck.

Scoop anchors weighing from 10 to 65 pounds are used for boats from 13 to 60 feet in length. Again, you need to purchase a heavier anchor if your boat is lengthy and heavy.

Mushroom Anchor

  • Perfect for muddy, weedy bottoms
  • Lightweight and easy to store
  • No pointy edges
  • Doesn’t damage the seabed
  • Cheap
  • Not great for hard mud, hard sand, or rocks
  • Not good for medium to large boats

Best for small boats under 21 feet

It is obvious from its name that a mushroom anchor is shaped like a mushroom. Mushroom anchors usually work in conditions where mud, silt, or sand shape the seabed. Other materials, including rocks, cannot grab mushroom anchors firmly.

Mushroom anchors need a counterweight to become buried in the seabed. It is used to make the shank lie down before it is buried. Mushroom anchors continue sinking into the seabed until they have moved the same mass as themselves. In other words, they can displace a huge amount of material and provide firm holding power.

To remove a mushroom anchor from the seabed, you need to dislodge the sand or mud surrounding it until the tension between the head and the seabed is weak enough for the motors on the structure to lift the anchor. This can be done by lifting it straight up with the rope or chain attached to it.

Fisherman Anchor

  • Look great
  • Extremely heavy
  • hard to store
  • damage seabeds
  • don’t hold all that well

Best to be used as a decoration piece and not for an actual anchor

Fisherman anchors are able to firmly hold rock and weed, but their tiny flukes can drag on any other bottoms. Fishermen tend to drop their anchors where the fish are more likely to exist, like over reefs and rocky outcrops. It is not a big problem if their anchor drags, as they can simply re-anchor it.

Fisherman anchors are tough to handle. If you need them to provide strong holding power, you have to choose one that is extremely heavy. In addition to that, these anchors are considered dated, and very few people actually use them anymore.

They exist now for more as a decoration than to actually be used as there are many better options available.

How Deep Do Anchors Go?

Anchors are designed to dig into the seabed to prevent the boats from moving. They can hold the boat working together with their chains. Now, the question is, how much chain do you need?

A rule of thumb states that you generally need a chain as long as 5 to 7 times the depth of the water. Therefore, if the water is 20 feet deep, for example, you need at least 100 feet of chain.

The maximum depth that an anchor can go depends on the combination of the depth of the sea and the length of the chain.

How Many Anchors Do Boats/Ships Use?

Most of the time, it is enough to have only one anchor to keep a boat or ship in place. However, having only one anchor can make the ship move in a circle during tide and wind shifts. That is why sometimes ships need a second anchor off of the stern to maintain their position with minimum movement.

The other reason why some ships and boats have two anchors with them is that anchors can be lost easily due to heavy winds, bad weather, strong waves, etc. Also, different seabeds require different types of anchors, and this is another reason why it is recommended to have more than one anchor in the boat.

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