The editors at Cruising World have teamed up with the experts at Imtra to bring you advice on how to keep your boat in Bristol condition and get the most from your hours spent out on the water. For more great tips, see Smoother Sailing with Imtra »
The process of successfully anchoring begins with choosing the right equipment for your type of boat, and then maintaining the components of your anchoring system for easy deployment and retrieval. For the purposes of this piece, let’s assume that your boat is 30 to 40 feet long, has a powered windlass, and has an adequate-sized anchor appropriate to local anchoring conditions. Our focus is on your choice of rode, which is what provides the connection between anchor and vessel. For more on windlass selection, read “How to Choose the Right Anchor Windlass.”
Broadly speaking, you can choose from three types of anchor rodes—all-rope, all-chain, or a combination of rope and chain. Before we discuss each in detail and begin considering the right match for your boat, here are a few anchoring concepts that will impact your choice.
Key Anchoring Concepts
First, the type of anchor windlass and the size of the anchor locker on your boat will factor into what’s selected. If you have a small anchor locker, an all-chain rode may be your only choice, because a combination rope/chain rode takes up substantial space. Your anchor windlass may also limit you to an all-rope rode, or a very short length of chain with rope, if it doesn’t have a chain wheel (also called a gypsy).
Windlasses are either vertical or horizontal, referring to the orientation of the axis of the chainwheel, and vertical windlasses are often set up to accommodate rope or chain, while a horizontal windlass is usually set up, and better suited, for chain only.
Our second anchoring concept is simply a reminder of the value of using chain. The weight of a rode that includes chain sinks more towards the seabed floor, which creates a better angle to set an anchor and keep it set when compared to an all-rope rode. Breaking it free may require more power, however, typically supplied by your boat’s engine as it moves you forward to a more vertical position over the anchor.
Finally, there’s the matter of scope, which is the ratio of the length of the anchor rode you deploy compared to the depth of the water you’re anchoring in. Generally, we recommend using a 7:1 scope when anchoring with a rope or combination rope/chain rode, whereas when using all chain rode, the scope can be a little as 4:1. In certain conditions, a combination rope/chain rode with a length of chain equal to, or longer than, the boat’s length may be adequate at 5:1 or 6:1.
Rope Anchor Rode
One of the chief advantages of a rope anchor rode over a chain rode is that it stretches under load, and we recommend nylon rodes to take advantage of this characteristic. Not only does a stretchy anchor rode reduce the likelihood of damage to the hardware on the boat, but it also reduces the tendency of the anchor to pull free of the bottom in strong gusts of wind or surging waves.
Rope rodes are typically made of traditional three-strand or 8-plait nylon. Plaited rope flakes well and is excellent if you have a small anchor locker, but it has a shorter life span and costs 35 to 50 percent more. Keep in mind, some windlass chainwheels do not manage plaited rope as well as they handle three-strand.
Three-strand rodes can be fabricated with soft, medium, or hard “lay” fibers. We recommend medium-lay nylon. While three-strand is cheaper and lasts longer, it tends to stiffen over time and begins to coil like a garden hose as it ages. You can delay replacement for a period by putting the nylon rode in a bucket with water and fabric softener. This will soften the fibers and may extend the life for an additional season or two.
If you’re using a powered windlass with rope, rope and chain, or chain only, take note that you can damage your windlass if you use the windlass as a cleat and it absorbs a heavy enough strain or shock load. If you have a combination rope/chain rode, it is strongly suggested that you take the load off the windlass by transferring the load to a deck cleat. This will extend the life of your windlass. In the case of all chain, the use of a snubber is suggested and detailed below.
Rope and Chain Combination
Those who rely on rope anchor rodes often add a small amount of chain at the anchor end, likely 15 to 20 feet for a boat in the 30- to 40-foot range. To a degree, this helps reduce the angle of the rode and anchor shank when the anchor is set, which can be especially useful when trying to set your anchor in a weedy bottom. Also, because the chain is the section of rode in contact with the bottom, this can reduce chafe on the lower end of your rope rode if it encounters a coral head or a rocky bottom.
Most windlasses are set up to accommodate combination rodes, and they typically have a spring-loaded pressure finger that helps keep the rope in contact with the chainwheel. Often, the most challenging part of rode recovery occurs at the splice where the rope doubles in diameter. This is where a tapered splice is critical. It’s worth noting that if you’re using plaited rope, some less-expensive brands flatten out and can get stuck under the pressure finger. We find that premium brands, such as those made by Yale Cordage or New England Ropes, don’t flatten and avoid that problem.
Sometimes the spring on the pressure finger has loosened, and it may pause on the splice and begin to chew up and damage the rode. Your recovery technique can save this from becoming a serious problem. Slow the windlass as it approaches the splice. Bump or jog the activation switch as it makes the transition from rope to chain. Then get the spring adjusted or replaced when you return ashore. Whether the spring tension is an issue or not, slowing the windlass through the transition will likely improve rope-to-chain management.
Another challenge with rope/chain combination rodes is using the proper splice to connect the two so your windlass can smoothly transition from the rope to the chain. For plaited line, we recommend a tapered back-splice to the point of transition; otherwise, the splice will be twice as thick and more likely to hang up on the chain wheel.
For three-strand rodes, a tapered back-splice is also critical. It’s worth remembering that the nylon strands will shrink as well as stretch. Therefore, during the splicing process, we put a fid between the first link of chain and the rope to introduce a gap and allow for the needed flexibility when turning around a relatively small-diameter chainwheel. Over time, three-strand nylon may get stiff and then maybe it’s time to replace the line.
We also recommend leaving the “splice-tails” as long as the diameter of the rope, then burning the ends to prevent them from unravelling. The extra tail accounts for the inevitable stretching of the splice when it is put under load when setting the ancour the first two or three times. Windlasses will sometimes chew these up but that’s better than if you have burned them too tight and as the splice “sets” they pull through and the splice unravels.
All-Chain Anchor Rode
If you have an all-chain rode for your boat, you are counting on your windlass to do all the lifting. One benefit is that typical scope can safely be as little as 3:1, so you need less swinging room in the anchorage, and you need to buy less chain, which typically costs $4 to $8 per foot.
With all-chain, we strongly recommend that you use a nylon snubber when anchored. This is a piece of rope tied or connected to the chain with a grab hook to take the stress off the windlass and transfer the load to the deck hardware. The snubber also provides for an easier motion while anchored, as the rope stretches when your boat surges against it.
Often a snubber is 20 to 50 feet long, with a chain hook at the end; this works well unless the wind dies, the current slackens the rode, and the chain hook can sometimes fall off. If you can, source a chain hook with a rubber strap to secure it in place. Another option is to simply put a hitch knot around the chain instead of a hook.
An all-chain rode can work on either a vertical or horizontal windlass, and all windlasses require purpose-built chain. There are many sizes, grades and materials available. You must pair your chain correctly to the chainwheel installed on your windlass. If the wrong diameter or type of chain is selected, the chain links will not fit properly in the “pockets” of the chainwheel and it will likely jam or skip and jump when you activate the windlass. Certain windlasses may only have one or two options for chain size and type, where other models may have over a dozen options when you include metric, imperial, and other global methods of measuring and manufacturing chain.
Here in the US, we generally encounter Imperial chainwheels. However, if the vessel was built abroad, a European metric or Australian metric chain may be required. That can get tricky, as sourcing these chains in the USA is sometimes problematic.
It’s critical that you identify the exact chain suited to your chainwheel. The windlass manufacturers commonly cast or emboss code numbers that can be cross referenced to define what’s needed. At Imtra, we have cross-reference guides available for the Muir and Lofrans brand windlasses that we offer. You may need to reach out to your windlass manufacturer for assistance with identifying your specific chainwheel. If your chainwheel is worn or you feel it is under or oversized to your anchoring needs, you can review the options for replacing it with another size/type.
For recreational vessels in the 30- to 40-foot size range, 5/16″ or 3/8″ are common sizes based on their weight and strength characteristics. Some windlasses may offer a Grade 30 (G3) Proof Coil chain or Grade 30 BBB, or, most commonly, a Grade 43 (G4) High-Test.
It is critical that calibrated ISO-specified windlass chain is selected. NACM (North American Chain Manufacturing) specification is not the same as ISO, and if you mistakenly source this chain, it will not operate in your windlass chainwheel.
Acco brand is the most common USA-built ISO-style windlass chain. Acco stamps “G3” on their Proof Coil links, “3B” on their BBB links, and “G4” on their High-Test links. Grade 43 (G4) High-Test is often twice as strong as Grade 30 chain. For sizes 5/16″ and 3/8″, both Grade 30s are galvanized and have a working load of 1,900 pounds and 2,650 pounds, respectively. Grade 43 has higher working loads of 3,900 pounds and 5,400 pounds, respectively.
We often hear questions about Grade 70 chain. This is a rather misunderstood product. It is known in the chain industry as “Transport Chain.” In its natural form, grade 70 has a higher tensile strength than Grade 43 but it is NOT galvanized. Grade 70 is also NOT calibrated chain, which means that there is less consistency in each link’s specifications than ISO-fabricated windlass chain. Once galvanized, Grade 70′s strength is also reduced by 10 percent due to the process. At that point, it is only marginally stronger than calibrated Grade 43 (G4) chain.
Another option is to select 316-grade stainless steel chain, which looks good, but because of varying tensile strengths, may not be as strong as galvanized. It often comes from the Far East and is not calibrated, so it can jam in a windlass. At Imtra, we offer stainless steel chain that is not calibrated but is sized to high-test measurements and will fit your windlass.
One final word on anchor rodes: You should never have a truly all-chain rode. Add 15 feet or more of rope to the end of the chain in case of a situation where you need to lay out an extreme amount of scope. Or in the event that you face an emergency situation and need to cut your anchor rode free as the bitter end will be secured to an eyebolt or fastening device at the bottom of the anchor locker.
For more information, visit imtra.com »