Benefits of a bow eyeSep 22, 2011
Many, if not most, long-range power voyaging yachts utilize all-chain anchor rodes, or at a minimum a long length of chain backed up by nylon so that the majority of the time the boat is secured by nothing but chain. This makes a lot of sense when anchoring in areas with possible chunks of coral or rock on the bottom (most of us try to never anchor on live coral), and is also useful because of the reduced scope necessary due to the weight and drag of the rode. However, the use of chain necessitates the use of a snubber line to add some elasticity to the system.
Experiments by knowledgeable boaters have indicated that an all-chain rode can become nearly bar taught in as little as 30 knots of wind, and when that happens tremendous shock loads can be delivered to your deck gear as the boat begins to surge on waves or in gusts. This problem is exacerbated by the modern trend towards using high-test chain, or chain that has a higher breaking strength at a smaller wire size, resulting in less weight, and even less of a catenary effect to be straightened out.
The typical anchor set up includes a bow-mounted windlass some feet back from the bow, with the chain leading over a roller down to the water and eventually the anchor. Many people use a single snubber line, often made of three-strand nylon for maximum stretchiness and good strength, led from a bow cleat, sometimes over the roller or not. Others use two snubber lines, one from either side of the bow, to create a small-based bridle, which may provide some assistance in keeping the bow into the wind. This system generally works well in many situations, but there is an alternative that can reduce the amount of chain needed, and can reduce your swinging circle.
The answer is to introduce a strong bow eye near or at the boat’s waterline, where the anchor snubber can be attached to provide a lower angle of pull and therefore reduce the length of rode needed to obtain the necessary angle at the anchor for maximum holding power. Some simple calculations can indicate how effective a bow eye can be. For example, let’s say you are anchoring in 10 feet of water. (In a nice clear Bahamian anchorage, this might be typical.) With a bow eye attaching your rode at the waterline you would only need 50 feet of rode to achieve the desired 5:1 scope. However, if your anchor roller is only five feet above the waterline you will have to add that five feet of bow height and then multiply by a factor of five meaning you will need 75 feet of rode to get the desired scope — a dramatic 50 percent increase in length! If your bow is eight feet above the waterline, add 40 feet of chain to the original figure. Those of you who have anchored in some narrow Bahamian anchorages (or in a crowded harbor like Cuttyhunk Island, Mass.) can appreciate what a dramatic difference this extra swinging radius can make.
There are other advantages to using this technique. If you have a large enough eye at the waterline, you can attach the snubber by just passing a spliced eye through. This way you don’t have the additional worry of an attached shackle to eventually corrode and rattle every night. Using a snubber attached with a spliced eye can dramatically lower the amount of noise transmitted into the boat on a windy night, as the line won’t be sawing back and forth over your anchor roller, possibly rattling the chain as it does, or squeaking at the cleat in each gust.
I have used a snubber attached like this for many years and there is virtually no visible chafe at the boat end — the snubber will need to be replaced first due to chafe where it attaches to the chain, or more likely due to age and weathering.
This total lack of chafe in the system is a wonderful attribute. No longer are you struggling out on your pitching bow on a rainy and black night trying to get some chafing gear to stay in place as the wind surges. If the snubber is short enough to prevent the line from reaching the bottom, you have nearly perfect chafe avoidance. Chafe avoidance can be perfected by practicing and using a rolling hitch to hold the nylon to the chain, thereby eliminating the potential chafing point where the line attaches to a chain hook. A properly tied rolling hitch is quick to do, has no cost, will not slip on the chain, won’t come undone, and is infinitely adjustable.
For one reason or another I have needed to make my snubber very short or very long, or more often in between. I just make sure the line on the bow eye is plenty long enough for any foreseeable situation, then I tie in the rolling hitch at the length I prefer for the situation. Generally I like to use less line than the water depth, but a minimum of six feet or so. In stormy conditions it is nice to have a 20-foot or longer snubber.
The one major drawback of this system is that to let out more chain you will need to pull in enough rode to get at the snubber line knot. This can be tough in that middle-of-the-night storm. However, the reduced rode length requirement of the bow-eye method means you are more likely to have out adequate scope in the first place, and be less likely to need that extra chain when the wind picks up.
John Kettlewell is the publications and marketing director of the Adirondack Mountain Club, and the author of numerous boating articles and books, including The Intracoastal Waterway Chartbook. He and his family recently completed a two-year cruise to the southwestern Caribbean aboard their 38-foot motorsailor, Minke.