Anatomy of an Anchor
To get an idea of how each anchor type works we must know each of its parts and functions. The shank is the stem of the anchor in which direction is pulled to set (bury) the anchor. The crown connects the various parts of the modern anchor. The stock turns the anchor into an attitude that enables the flukes to dig into the sea bed. The optional tripping ring is used for tripping with a separate line, allowing the anchor to break out. The flukes will be buried into the seabed. The very tip of a fluke is sometimes called the bill.
Traditional Types of anchor
There are 6 main types of anchor. They are the Fisherman, the Claw or Bruce, the Plow or Plough, The Fluke, the Grapnel and Mushroom. Each of these families has many anchors that relate to the basic design principle. For example the Plow type named because it acts like a farmers plow, has the CQR and Delta which belong to this anchor family.
The fisherman is a traditional design and is often seen on the bows of old Sailing Ships like HMS Victory. The design is a non-burying type of marine anchor, and grabs rocks with one arm penetrating the seabed and the other standing proud. It has a good reputation for use in rock, kelp, and grass. However its holding power to weight ratio is among the worst of all anchor types. The primary weakness of the anchor design is its ability to foul the cable over changing tides. One of the Fishermans arms can catch the anchor Rhode or cable and accidentally trip the anchor. It is difficult to handle and bring aboard without scarring the topsides and does not stow well in an anchor roller.
The Fisherman is best suited for rocks, and kelp bottoms, but not good holding in sand or mud. The Fisherman has arms which lodges themselves in a rock bed, or as in grass and kelp, the arms allow the anchor to penetrate through the kelp.
Modern examples of fisherman type anchors include; Luke Storm Anchor, kedge and Navy.
The Bruce anchor was designed by Peter Bruce back in the 1970s. The Bruce also known as the Claw. Claw-types set quickly in most sea beds and although not an articulated design, they have the reputation of not breaking out with pull direction, instead slowly turning in the bottom to align with the force. They offer a fairly low holding power to weight ratio and generally have to be over-sized to compete with other types. On the other hand they perform relatively well with low rode scopes and set fairly reliably. The traditional Claw anchor has rounded flukes. The Claw Anchor showed poor performance in the many anchor tests, which are attributed to the anchor failing to dig in, due to the rounded flukes. The Rocna Spade and Supreme anchors faired much better and many anchor tests. The Rocna Spade and Supreme anchors and are among a new breed of anchor with roll bars and/or pointed tips.
Claw anchors are best suited for sand and muddy bottoms where the design can dig in. Claw types boat anchors have difficulty penetrating weedy bottoms and grass, tending to float over weed and kelp rather than digging in.
Modern examples of claw type anchors include; Bruce, Claw, Rocna, Spade, and Supreme
Plow or Plough
The plows holding power over a wide variety of bottom types, makes it a top choice of cruising boaters, named for its similarity to the farmers plow. When dropped in the water, a plow often lands on its side. However when pulled by the ground tackle, the Plow buries itself. Its shape allows it to reset fairly easily should the wind or tide shift the boat position. Many manufacturers produce a plough-style design, all based on or direct copies of the original CQR the Coastal Quick Release. The CQR design has a hinged shank, allowing the anchor to turn with direction changes rather than breaking out, and also arranged to force the point of the plough into the bottom if the anchor when it lands on its side. The more recent Delta uses an unhinged shank and a plough with specific angles to develop slightly superior performance. Owing to the use of lead or other dedicated tip-weight, the plough is heavier than average for the amount of resistance developed, and may take a slightly longer pull to set thoroughly.
Recommended for bottom surface; Works well on many bottom surface types. Sand, mud, and kelp grass.
Modern examples of Plow type anchors include; Delta, CQR Plow or Plough
The fluke style anchor, named due to its large flukes, uses a stock at the crown to which two large flat surfaces are attached. The stock is hinged so the flukes can orient toward the bottom (on some designs the flukes angle can be optimized depending on the bottom type.) The design is a burying variety, and once well set can develop an amazing amount of resistance. Its light weight and compact flat design make it easy to retrieve and relatively easy to store; some anchor rollers and hawse pipes can accommodate a fluke-style anchor. A few high-performance designs are available, such as the Fortress, which are lighter in weight for a given area and in tests have shown better than average results. Once set, the fluke anchor tends to break out and reset when the direction of force changes dramatically, such as with the changing tide, and on some occasions it might not reset but instead drag.
The fluke is recommended for sand and muddy bottom surfaces. The fluke anchor has difficulty penetrating kelp and weed-covered bottoms, as well as rocky and particularly hard sand or clay bottoms. If there is much current or the vessel is moving while dropping the anchor it may float over the bottom due to the large fluke area acting as a wing.
Examples of Fluke Anchor types; Fortress Danforth and Guardian
The grapnel style is simple to design and build. The design is a non-burying variety, with one or more tines digging in and the remainder above the seabed. In coral it is often able to set quickly by hooking into the structure. A grapnel is often quite light, and used aboard smaller boats where its weight makes it relatively easy to bring aboard. The Grapnel is sometimes difficult to retrieve
Grapnels rarely have enough fluke area to develop much hold in sand, clay, or mud. It is not unknown for the anchor to foul on its own rode, like the fisherman, or to foul the tines with refuse from the bottom, preventing it from digging in. It is quite possible for this anchor to find such a good hook that, without a trip line, it is impossible to retrieve.
Mushroom anchors work best in soft muddy bottoms, where they can create suction which can be difficult to break. Recommended for small boats to use as a lunch hook, but not practical for larger boats.
I read somewhere a question from a new boater who asked if they needed an anchor. The answer is yes you do its required by law in many places and it can be one of the first pieces of emergency equipment you’ll need. Whether you sail up a river, or cross oceans an anchor is an essential piece of gear.
When choosing which anchor is best for you, consider the important factors are reliability to set, holding power, veering and damage/storing. Which bottom surface do you need your anchor to work in? How big a boat are you operating? Are you fishing or riding out a storm?
This article will give you a guide to the various types of anchor old and new. Which types of anchor work in which bottom surface, is important to you. The good news is that the newer anchor technology appears to be working and from the anchor tests we looked at the new designs outperformed the tradition types.
In part 2 of anchoring, we provide information on ground tackle & anchoring techniques to help you stay anchored in challenging conditions.