A plow anchor mounted to the bow of a boat docked to a pier in the Caribbean

A boat anchor is that lovely metal device that we attach to our boats typically by chain and lowered to a seabed to hold our vessels in place. Without a trusty anchor, your boat will drift and possibly collide with other vessels, rocks, or get stuck in shallow areas. Obviously, anchors are very important when stopping and holding your boat across different bodies of water, but the water type or bottom might warrant a unique type of anchor. Let’s discuss how boat anchors work in general, and how each of the different types of anchors, such as fluke, delta, grapnel, and plow, work in their own unique way to keep your boat safely secured.

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How Does a Boat Anchor Work?

How boat anchors work is they penetrate the surface of the seabed by using suction, dragging material from the bottom over the anchor. This added weight helps the anchor grapple into place, digging deeper and creating additional resistance. If there are additional items on the seabed the anchor hooks on to, that helps keep the boat in place as well.

Anchor Setting refers to the “sets” that apply tension to the rode, so the anchor securely penetrates the seabed, fastening it into place. How to properly set the anchor is by applying power in reverse while making fast the line. The way you know you did it correctly is if your boat does not move or drift. If it does, reset the anchor and do the process again.

Anchor Scope is a ratio of the length of an anchor node from its bit and the water depth under the bow of boat measured from the height of the deck. Once the anchor is set successfully, it is supposed to hold an equal amount of tension that was used to set it, even if the scope is reduced. If your boat swings and the anchor has to be reset, you may have to do it at a reduced scope.

Anchor Resetting happens when the anchor is dislodged from the seabed due to a change in current or various angles of pull. If you notice your boat swinging, that is a sign for you to reset the anchor. A good way to tell if your anchor has separated from the seabed is by:

  • Checking if you have an anchor alarm on the chart plotter.
  • Set a course alarm if you have an electric compass or autopilot.
  • Set up maximum and minimum alerts to track sudden changes in water depths.
  • Stand an anchor watch to detect a subsequent change in position.


How a Fluke (Danforth) Anchor Works

A man on the bow of a boat throwing a fluke anchor into the water to anchor his boat

A fluke style anchor (otherwise known as Danforth) is a uniquely designed anchor and it is lightweight. This anchor secures boats by digging its pointed flukes into bottom sediments, which are good for most pleasure crafts.


How a Delta Anchor Works

Close up view of a delta anchor out of the water hanging of the bow of a boat

First made in the 1980’s, the Delta anchor is similar to a plow anchor and known for its maximum holding power. Its open design enables it to easily penetrate multiple seabed conditions, making it self-launching. Due to this unique design, many lifeboat organizations have designated the Delta anchor as their primary anchor.


How a Grapnel (PWC) Anchor Works

A grapnel anchor under water digging into the sandy bottom of a clear body of water

Grapnel anchors display four tines that splay open while the anchor descends onto the seabed. A unique benefit of this anchor is that it can easily be folded up for easy storage compared to other types. Once it has made contact with the water bottom, it rolls on its side and one or two of the tines dig deep into the sediment, providing a secure hold.


How a Plow Anchor Works

Zoomed in picture of a plow anchor mounted to the bow of a boat

Plow anchors lay on its side and buries itself underneath the seabed once pulled and locked into place. With its unique curved design, the plow anchor allows for sediment and sand to cover the top of it, adding more weight so the anchor sinks deeper into the bottom. This allows for maximum hold, so your boat does not swing or drift away.


Premium, Corrosion-Resistant Stainless Steel Boat Anchors for Sale

As a leading player in the industry, Sardine Marine is an expert in boat anchoring and provides an in-depth knowledge on how to anchor boats with every type of boat anchor out on the market. We carry a supply of premium marine-grade, corrosion-resistant, 316 stainless steel boat anchors of all types depending on what you are looking for future days on the water. We have fluke anchors, delta anchors, grapnel anchors, etc. on sale that meet your boating and anchoring needs. View our current inventory at: https://www.sardinemarine.com/collections/anchors.

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By Jim Radack


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