Anchors support ships on the water and keep them from drifting into the ocean. These anchors can vary, but a ship anchor is typically quite considerable. Learn some interesting facts about this piece of marine equipment.
The anchor of a cruise ship is usually between 10-20 feet long, weighing in at around 10 to 20 tons. Most modern-day vessels will have more than one, such as the RMS Queen Elizabeth, which had three anchors when it was first built. These larger ships need them so they can stop at sea. If anything happens while you’re underway, your crew has time for safety procedures before things go south quickly.
You might think of anchors as simply something that keeps boats anchored — they’re not supposed to be very big. But there’s more to an anchor than keeping a ship from floating away. It also has other essential functions.
For example, if you were anchoring a sailboat with two masts downwind, one mast could snap off because of wind pressure on the top part. An anchor prevents such damage by providing stability. Other uses include helping drag another vessel into port after being detached from the original ship during battle maneuvers and pulling up onto a dock to make repairs safely without damaging the hull.
In addition, even though modern vessels often use synthetic rope instead of natural fibers, anchors still need their line to prevent them from slipping through the hawse pipe openings.
These days, anchors come in all shapes and sizes, from small pieces of metal weighing only 2 pounds (0.9 kilograms) to huge iron blocks weighing hundreds of tons. Some of the giant ships in the world have anchors known as “cable” anchors.
These anchors consist of three parts: a steel cable called a rode, which runs between two massive wooden poles, or piles, driven into the ground near the seashore. This arrangement makes it possible to securely attach the end of the road to the bottom of the mound using either a chain locker or a capstan winch.
Then a smaller pulley attached to the middle pole allows the rode to slide freely over the crossbar while the ends of the steel cables inside the pole run along grooves cut deep into the side of each pile.
The largest active naval fleet in the world belongs to Russia. With almost 1 million men under arms, it’s no surprise that the Russian navy needs some big anchors to hold those ships together!
This article will look at what makes an anchor: weight, shape, material, gearing, and even where anchors originated in ancient times. First up, let’s find out why they’re so heavy.
Why Are They So Heavy?
A typical commercial ship will carry anywhere from 8,000 to 20,000 anchors, depending on the type of ship and the owner’s preferences. When you consider how anchors can be put to work, you understand why they weigh so much. Let’s take a closer look at the essential components of a standard marine anchor.
It turns out that anchors aren’t cumbersome items. You’d expect them to weigh far more since they perform several vital tasks. However, most anchors contain certain elements that contribute to their overall bulkiness. We’ll start with the shank, the long shaft that extends downward from the head of the anchor.
If you’ve seen pictures of anchors before, you know that the heads usually feature multiple flukes, sometimes four, six, or eight. Each fluke provides additional holding power. Because the anchor must penetrate solid matter, it doesn’t need to be able to lift any significant amount of weight. Instead, it depends upon friction to slow down enough so that it won’t slip past. To achieve this effect, the anchor must be appropriately weighted.
Most anchors are designed to withstand 500 pounds per square inch (psi). When you see those numbers mentioned earlier, you should understand that “weight” primarily refers to the force needed to raise the anchor, buoyancy, and gravity forces.
The actual psi rating depends on whether the seafloor is soft mud or hard rock, how thick the anchor body is, and the shank length. Even though most anchors can handle 50 percent greater stress than 500 psi, engineers try to avoid breaking them by exceeding 600 psi. However, this isn’t necessary because anything beyond 500 psi requires special care and maintenance to ensure continued performance.
Once the anchor gets stuck below the water’s surface, it becomes subject to constant movement due to waves and tidal currents. Marine anchors, unlike land-based anchors, tend to wear down quickly because of this motion. Many types of anchors incorporate replaceable weights that allow owners to adjust the total mass of the anchor to compensate for changes in soil conditions.
Now that we’ve taken a peek behind the scenes of an average anchor, let’s talk about the materials used to make them.
What are the best kinds of anchors? Today, many choices range from simple wood plugs to highly specialized devices explicitly built for particular purposes. Since people don’t always want to bring extra supplies aboard their ships, here are some standard options:
Davitts – Davits are portable anchors that screw directly into holes drilled into underwater structures. One advantage of davit anchors is that they require less time to set than conventional ones, which means fewer man-hours lost to installing them. Another plus is that they cost significantly less than more prominent anchors. On the downside, they lack good gripping ability, making them unsuitable for rocky bottoms.
Chain Buoys – Chain buoys are similar to davits except that they are permanently installed. Their main drawback is that they offer poor holding strength compared to other anchors.
Rope and Wire Cushions – Ropecuffs and wire cushions are popular among boaters who prefer to leave anchor installation to professionals.
Fiberglass Dragging Beams – Fiberglass dragging beams serve as emergency anchors for disabled cargo ships.
Steel Cable – Steel cable anchors provide maximum holding capacity. Although relatively expensive, they are widely used by commercial fleets.
Let’s say you decide to purchase an anchor. What else does it take to choose one that suits your specific needs? Next, we’ll explore some features that determine an ideal anchor.
Choosing Your Ideal Anchor
First things first: How do you plan to deploy your new anchor? Will you be going offshore or inshore? Do you intend to cast it overboard, or will you hire someone else to do it for you? Once you answer these questions, you’ll be better equipped to select an appropriate anchor style.
Here are some general guidelines:
For coastal applications, stay away from fiberglass or plastic anchors. Those types of anchors will sink too fast once dropped into shallow waters. Also, because of limited space onboard, they wouldn’t fit well within the bowels of a ship.
On the other hand, opt for heavier models if you plan to drop anchors deep into rivers, bays, or harbors. Otherwise, pick lighter anchors.
You can build your version of an anchor using a woodblock, a drill, and a nail gun. First, carve out your desired shape and mount nails around the perimeter. Next, use rubber mallets to pound the nails into place. After drilling proper hole patterns, insert the hooks at opposite sides of the base plate until they touch the seafloor. Now you can hang your homemade anchor by attaching lengths of rope to the hook points and tying it to a cleat mounted on the deck of your boat.
Most professional anchors fall into one of five categories based on usage:
Tautliner anchors are used mainly for supporting taut lines. Examples include spring rings, shackles, turnbuckle chains, and catenary wires.
Buoyant anchors help suspend boats above the water level by utilizing compressed air tanks and ballasted bodies.
Dragline anchors function similarly to buoyant anchors, employing hydraulic rams rather than bladders.
Lifting anchors pull objects ashore by engaging gears located at the lower portion of the anchor itself.
Like everything else related to the oceans, anchors evolved gradually. Ancient Egyptian stone anchors dating back 4,000 years ago resemble the anchors used in Roman times. By the Middle Ages, European mariners had developed wooden anchors embedded with iron bars and spikes.
During World War II, U.S. Navy divers explored the possibility of burying submarine mines with tiny anchors to lure enemy ships close enough for detonation.
