One of all-chain rodes most popular features among cruising sailors has little to do with anchoring-and everything to do with stowing. With a well-designed bow roller, windlass, hawse hole, and chain locker, your rode and anchor will deploy and stow belowdecks faster and with far less effort than nylon rode requires. But for a smaller boat without a windlass or deep chain locker, an all-chain rode is often impractical. Even cruising sailors who are perfectly equipped for all-chain anchoring often find that their nylon secondary anchor better is suited for some anchoring situations.
Low cost and versatility make three-strand nylon the nearly universal choice for rope anchor rode, so when we say all rope, we mean nylon, three-strand (see Anchor Rode Report, PS February 2014, and High-Tech Anchor Rode, PS August 2018). PS will explore other fibers in a future article.
In addition to the need for more scope in deeper anchorages, nylon rode presents some not-so-obvious downsides-a higher risk of the rode wrapping your keel or rudder, less resistance to chafe on rocks and coral, and a greater tendency to yaw and wander in light winds. Many books suggest these problems can be minimized by using a kellet (aka sentinel), a heavy object that weighs down a nylon rode to induce some sag, or catenary. But how much help does a kellet actually provide?
Over the course of the past years, PS testers have collected anchor and mooring load data on a variety of boats in different conditions. We combined that data along with some more recent experiments using kellets to try to quantify their effectiveness. The two adjacent tables illustrate our findings regarding a kellets ability to induce catenary.
For modeling, we used the example of 30-foot cruising boat, with dimensions similar to a Catalina 30, using a 1/2-inch diameter nylon rode and 30 feet of 1/4-inch G30 chain. A heavier kellet will create more catenary, but greater than 20 pounds becomes cumbersome. Although we recommend a minimum of 60 feet of chain, 30 feet of chain is also commonly recommended. Many pre-spliced rodes come with a 30-foot chain lead.
For sailboats much smaller than 30 feet, a kellet is generally unnecessary. Likewise if you use an all-chain rode, a kellet will be of little use. If you use all-chain rode, deploying 10-20 feet of additional chain (depending on chain size) will give you all of the benefits of adding a 20-pound kellet, with less work.
Positioning the Kellet
The ideal position for your kellet can vary depending on what you are using it for. Fortunately, you can model the alternatives with a length of string and a small weight.
Placing the kellet closer to the bow immerses slack rode deeper sooner, making keel or rudder wraps less likely. To prevent keel-wraps place the kellet just forward of the bow, at about 150 percent of the water depth. This reduces slack and steadies the boat in calm conditions.
Placing the kellet closer to the anchor keeps more slack rode on or near the bottom, reducing the angle of pull (the angle between the sea bottom and the rode) on the anchor, which generally improves holding with nearly all anchor designs. To reduce the angle of pull on the anchor, place the kellet near to where the rode and anchor chain join. There, in light winds, it will sit on the seafloor without pulling the rode downwards where it can chafe and snag. The best compromise is typically about 30-40 feet away from the anchor, where the chain leader typically ends.
This placement allows the kellet to drag along the bottom, damping changes in wind direction. It also gives the chain leader room to do its work. Finally, it allows the rope to float up away from bottom chafe. In fact, it is best practice to attach the rode to the kellet via a 1- to 2-foot pendant so that the rode can float well above the bottom. Without this short extension, the rode will drag side-to-side across the sea floor, snagging on every stone, shell, and rusty shopping cart it can find.
In coral and rocky areas, a kellet should not be used; instead, use enough chain leader so that the section near the bottom is all-chain and the rope lifts up. Often the rode can be supported with a float to keep it from snagging on coral or rocks. Because of the tremendous harm a single sailboat can cause to a coral reef, anchoring in coral-alive or dead-should be avoided. Anchoring in coral is prohibited in many protected areas such as those in the Florida Keys.
To buffer storm forces, place the kellet in the center of the rode, where it will cause the greatest deflection. Some kellets are equipped with rollers to slide down the rode so they can be deployed at anchor. If you did not have the foresight to deploy your chain kellet in advance, you can usually shorten up the rode momentarily and attach it where required with a prussic hitch, and pay out the rode again.
Preventing Keel Wraps
We’ve twice witnessed keel wraps that led to big trouble. In both cases, thunderstorms preceded by a calm were to blame. In the first case, the skipper was aware that the rode had wrapped around the keel because of the odd angle at which the boat lay to the wind.
However, the rough conditions and high loads made it to dangerous to untangle the mess. Within 15 minutes the sharp trailing edge of the keel knifed through the rope and the boat was deposited unharmed on a mud bank.
In the second case, the keel-wrapped boat appeared to be anchored by the stern. It later became clear that the rode had wrapped around the rudder. Not only was the rode damaged, but the rudder shaft was also bent, just far enough that they couldn’t turn the wheel without considerable scraping. After some consideration, the crew limped home, but a hefty yard bill surely followed.
A kellet will help prevent rudder and keel wraps. It will generally stay on the bottom up to 10-12 knots, when the rope is relatively slack and prone to twisting. Higher winds will pull the rode reasonably taut between the anchor and the boat, and wont pose a threat of tangling. Although the optimum position is about 150 percent of the water depth in front of the roller (i.e. 36 feet past the bow roller in 24 feet of water), placing it a little deeper will also help reduce wandering in light winds, encouraging the boat to swing in unison with the boats on all-chain rodes.
Bottom line: A kellet is a practical tool for avoiding keel and rudder wraps in non-coral areas.
Reducing Angle of Pull
Ideally, the angle of pull, the angle between the rode and the sea floor at the anchor, should be as small as possible. As illustrated in the adjacent tables, a 20-pound kellet has negligible impact on the angle of pull on the anchor as winds rise above 30 knots. At short scope (3:1), the kellet begins to lift at about 12-14 knots, and by 30 knots, the difference in angle is less than 2 degrees. At moderate scope (5:1) the kellet will lift in the high teens and become ineffective at 35 knots.
Bottom line: A kellet is somewhat effective for maintaining a low angle of pull on the anchor. Youre probably better off focusing on a good power set at long scope before shortening up, and don’t shorten up too much.
Cushioning Storm Winds
Once the wind starts to blow hard, the kellet will become ineffective. Since we know that even all-chain has serious limitations at short scope in shallow water, how can we expect 20 pounds of iron to do what 150 pounds of chain failed to accomplish? If positioned in the center of the rode for best leverage, it will control the swing of the boat in up to 10 knots of wind in much the same manner as chain. Above that, boats tend to align with the wind anyway.
Bottom line: In higher winds, more scope is more effective than a kellet.
Either chain or a kellet will prevent a boat from wandering too much in light winds. But once the kellet (or chain) is off the bottom, it comes down to the balance between windage and underwater resistance. (See Anchor Rode Report, PS February 2014).
Bottom line: Yawing is best controlled by adjusting windage and underwater resistance.
No, you don’t need to run out and buy a kellet. Because a kellet is only effective in specific circumstances (wind against tide or a crowded harbor), all you need is a contingency plan, something you can easily rig-up using materials on hand. Here are some substitutes:
Spare anchor. We don’t like the idea of using a spare anchor, since the anchor may hook over the rope, increasing chafe. And you might need that anchor for its designed purpose.
More chain. If your goal is to minimize angle of pull, weight is best added close to the anchor. The simplest solution, then, is to add more chain to the leader. The added chain does the same thing as the kellet, but with less weight, better chafe protection, and reduced tendency to yaw.
If the goal is avoiding keel wraps, 30-40 feet of additional chain leader is generally sufficient. Even in a strong tidal race that induces a 180-degree turn, this will usually be enough eliminate the slack that can cause a keel wrap. However, in deeper anchorages, or when wind-against-tide cause the boat to wander and rotate, keeping the rode safely submersed requires additional weight. In these, more challenging cases, you’ll want to increase to at least 100 feet of chain, or change to a different arrangement such as a Bahamian mooring.
When it comes to buffering storm winds, a longer chain leader will help, but ultimately, it is the shock-absorbing characteristic of the nylon, either in the form or rode or snubber, is what will reduce the loads on your anchor, rode, and deck hardware.
For the average cruising 35-45 foot cruising boat, an all-chain road will only buffer the loads of storm winds when you deploy 250 feet of anchor chain or more.
Perhaps the best contingency kellet is 10-20 feet of spare chain, whether in one piece or multiple sections, either doubled or quadrupled over and secured to the rode with a prussic hitch. It does not endanger the rode, it is something you should have on hand anyway (as part of the secondary rode or for shore ties and rough dock), and it can be deployed over the anchor roller without leaning over the pulpit.
For storms and shock absorption, the kellet of yore is properly retired in favor of more chain and nylon snubbers. If tide-against-wind or crowded harbors are common for you, consider a longer chain leader, up to 100 feet. You derive most of the benefits of all chain rode, most of the time, without the weight or expense.
If these situations are rare, carry 20 feet of spare chain, possibly in sections. It is safe and easy to attach to the rode, and will come in handy for a secondary rode leader or mooring to rough poles and wharfs. If you have all-chain rode, adding a 20-pound kellet to several hundred pounds of chain is usually a waste of effort; deploying another 10 feet of chain is simpler.
The above tables illustrate how higher winds can render a kellet ineffective at absorbing shock loads. In both scenarios, the modeled ground tackle is 1/2-inch nylon rode, 20 feet of G30 1/4-inch chain leader, the depth is 60 feet, and the kellet is placed 90 feet (150 percent of depth) away from the bow roller. At short scope (3:1 scope ) the kellet begins to lift at about 12-14 knots, and by 30 knots, there is just a two degree difference between the angles at the bow of a kellet -weighted rode and one without a kellet. At moderate scope (5:1) the kellet will lift in the high teens and become ineffective by about 35 knots.
1. As winds increase the kellets work is done, and no longer exerts a measurable impact on the angle of pull.
2. In light winds and wind-against-tide scenarios, the kellet does its job by absorbing any slack in the anchor rode.