Mud isn't created equal, and no one anchor is best

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On Aug. 6, 2014, the 81-foot research vessel Rachel Carson pulled away from her dock at Solomons Island, Maryland. Powered by twin 1,205-hp MTU diesels and a pair of Hamilton jetdrives, she cruised into the Patuxent River and explored the bottom with the sophisticated equipment you’d expect the University of Maryland Center for Environmental Science to supply. Then she assumed a predetermined stationary position.

The University of Maryland Center for Environmental Science supplied the researsh vessel Rachel Carson to conduct anchor tests.

Men on the stern lowered an anchor with chain attached to a cable wound around a large steel drum, operated with precision by the vessel’s chief engineer. After the anchor reached bottom, the Rachel Carson moved to another position, paying out cable as she went and then maintaining position at that second spot. Then the engineer began reeling in the cable at 10 feet per minute. This anchor — and 10 others — were pulled for 100 feet, shortening the scope from 8-to-1 at the beginning to 5-to-1 by the end of the pull.

Sophisticated sensors measured cable tension continuously. This allowed assessment of the anchor’s resistance to the mud — in other words, its holding power. The data was transferred to computers at the engineer’s station at the winch control and to the computer array in the vessel’s workroom.

Linear graphing recorded changes in tension to show the amount of resistance as each anchor was pulled through the mud and also documented other factors, including the brand and weight of the anchor and position of the test run. The testing was done in consultation with Bob Taylor, a civil engineer with expertise in anchoring issues who has also done work for the Navy. This was day two of one of the most extensive and formal boat anchor tests I’ve witnessed.

I’d met the team the evening before and come aboard that morning, remaining throughout the long day. Company personnel from Fortress Anchors, which was conducting the tests, had traveled from the main office in Fort Lauderdale and the parent company in California. Members of the boating press had been invited and carefully watched every facet of the testing, free to move about and observe all that was going on. All results were available live, and great effort was taken to ensure transparency and equal treatment of all anchors. Tested were the Claw, CQR and Delta by Lewmar; the Danforth HT; the Mantus; the Rocna; the Supreme and Boss by Manson; the Spade; the Ultra; and the Fortress FX-37. Each was pulled five times during the four-day tests. Efforts to control variables included moving to a different position after each set of pulls to get fresh bottom and starting each pull in a set from the same location to the same location. This was possible, in part, because the Rachel Carson has a dynamic positioning system that keeps her in a designated position.

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This test didn’t answer all questions regarding anchoring or establish an absolute conclusion that one anchor is better than all others in all circumstances, but the results — as you can see in the graph — are compelling. Of course, it would be impossible to duplicate all of the conditions of everyday in-the-field anchoring in a scientifically conducted four-day anchor test, but the testing was undertaken objectively, following strict protocol and with reputable scientific methodology. Fortress conducted these tests out in the open, without knowing how they would turn out. The company invited the boating press to attend and observe. It’s important to me to see a company that’s willing to take these steps to provide information about its area of endeavor.

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Over the years I’ve had various types of anchors foiled by junk on the bottom — an old shoe that blunted the entry point of my CQR, conch shells on the entry point and, of course, line, cable and chain. My anchor once fouled on a very nice fisherman’s anchor. This prevented my anchor from getting a bite, but I did gain a very nice (muddy) Herreshoff.

Although the team conscientiously tried to position anchors for each test so that they would drag in the same area, you can’t do that perfectly. Different anchors, as will always be the case, encountered different obstacles to holding.

There was another significant variable that couldn’t be avoided. The vessel’s dynamic positioning equipment is truly impressive — I’d love to run a boat with dynamic positioning. The helmsperson tells the computer where the boat is to be, and the computer, using GPS, takes over the engines and thrusters to keep the boat on position. But, once again, the variables of being on a boat on the water were too much for the “scientific” approach.

With a vessel of this type, there will be pulls and pushes with the wind, the current, an eddy, bottom turbulence, waves and wakes. The ship’s station-keeping equipment corrects this, but in the meantime the vessel has moved 2 or 3 feet. If the vessel moved 2 feet toward an anchor being pulled through the mud, the stress would immediately spike down as though the anchor broke free. As the vessel corrected, the full force of those engines and thrusters would be transmitted through the cable and down to the anchor, and the stress would spike up, indicating that it was holding on with extreme power until it popped out.

The graphs on the computers weren’t showing what the testers initially expected. The only way to prevent this would have been to use a vessel that could be spudded down to the ocean floor for each draw. This would have taken forever and would have been much more expensive.

Taylor’s full report and findings are posted online at the Fortress website (fortressanchors.com, click on the “news” tab at the top of the page). He said that the most notable finding, according to Fortress, is the huge disparity in “ultimate holding capacity” for an anchor specifically configured for mud seabed. Changing the fluke angle from the regular 32 degrees to a mud setting of 45 degrees almost doubled the UHC of the Fortress FX-37 in mud. The bilateral fluke anchors tested — the Fortress and the Danforth HT — achieved the highest capacities of any of the anchors configured for general anchoring. The Ultra achieved the highest average capacity of the fixed-fluke (angle) anchors.

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I came aboard the Rachel Carson with a bias based on nearly 60 years of anchoring in every kind of bottom, in storms and hurricanes, even in two tornadoes, as well as 35 years of anchoring out almost every night. And occasionally I’ve gone underwater during storms to see up close and personal what different anchors are doing. So I’m comfortable with my bias, though other experienced people have different views, which I respect. And I should note that although I’ve used many anchors, I’ve hardly tried them all.

An assortment of anchors were tested over the course of four days.

I started using Fortress anchors a long time ago. A Fortress has almost never failed to set and hold for me, save for the few times I’ve put it down in a bad bottom, such as sandstone or thick grass. And a Fortress once broke free when I was forced to anchor in a bad bottom with currents that caused constant eddying, which made my boat repeatedly swing around the anchor in high winds. The chain caught under the stock and pulled the anchor out backward, and it was unable to reset. This is an inherent fault with this type of anchor (Danforth). It also bedevils many other types.

With any anchor it’s important to use chain (in some cases steel cable), rather than just nylon rode. My primary rode is all chain. I believe this is best, as long as you utilize properly rigged snubbing gear once you’re set. You need to pull your anchor on the bottom at an angle so that its flukes dig down, rather than slant up or are parallel to the bottom.

Use whatever “tools” you can to sense what’s going on below the water as the anchor sets. I keep my toes on the chain as we’re slowly backing down, and the chain telegraphs signals. For example, a smooth scraping vibration, as if the chain and anchor are being dragged along a sidewalk, means a very hard bottom. Small jerks mean we have to slow down a little. A rattling chain means rocks or a thick oyster bed. A nylon rode will absorb a lot of these messages. There are many more tricks, and none require hydraulics, computers or engineers.

Also, use the right anchor for the bottom and circumstances. The test, by necessity, was essentially performed in one type of bottom. Different anchors often work better in different bottoms. When I cruise, I have three types of anchors on board: the original CQR, a Fortress and a Herreshoff. I’ve found that the Herreshoff holds poorly in most bottoms. However, it will hold in two types of bottom when most anchors won’t. One is a rocky or hard bottom, such as shale or sandstone, that has holes or indentations. The point hooks in, and you’re usually tight until the wind or tide shifts. It’ll also usually dig through a bed of heavy grass with relative ease, hooking under the mat and giving you some security — until the last of the roots of that grass break around 2 a.m.

I prefer to anchor in mud or sand. The CQR sets well in mud if it’s not too loose and in soft sand. If the sand is hard-packed, the CQR can have problems setting. I prefer the CQR if I’m over a bottom that I know it holds well in and I’m going to be swinging from reversing directions or circling as weather blows through. The Fortress sets in almost any bottom — soft mud, thick mud, soft sand, packed sand. Neither the Fortress nor the CQR do well in rocky bottom or grass. I avoid these areas, but if weather traps us over these bottoms, I have the Herreshoff on board. I also have an unassembled Fortress FX-125 for my ultimate storm anchor. It’s easy to store, and I can retrieve and deploy it quickly.

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But to bring it down to you and me: If you can spend the money and take the measures described here to quantify anchor performance and still be bedeviled by the vagaries of the bottoms of rivers, creeks, bays and coves, what’s a boater to do?

• Bring more than one anchor and make sure they’re good, tried-and-true anchors. Don’t develop your preferences based on gimmickry, unrealistic boat show demonstrations, what any one person says or limited testimonials about how well one boat held in one bad storm. It’s more complex than that.

• Different conditions may warrant different anchors, and on very rare occasions, the deployment of two anchors may be needed. The two anchors on my bow are the original CQR and the Fortress. I wouldn’t be out without both of them. I seldom worry about the CQR being tripped by my chain if pulled in the opposite direction from the set, but I’ve found that there are bottoms where the CQR won’t set and the Fortress digs right in.

• Know your bottom. “So” on the chart doesn’t necessarily tell you the bottom is soft. Look at the banks. Drop your anchor and retrieve it to see what’s on it. Drop a small grappling hook, drag it around the boat and pull it up. Take into account your surroundings. If you’re in a narrow creek with a strong reversing current and high wind blowing across, you must plan for much less swinging room and zero tolerance for dragging and circling around the anchor. If the creek has little or no current, assume it may have a layer of poor holding “pluff” mud that’s black and loose, with very low viscosity. You’re most likely to find this condition at its worst in coves or quiet backwaters, where leaves and other foliage have been falling into the water for thousands of years with little or no current.

Knowing how to anchor securely is key to a peaceful night of sleep.

• Develop techniques that work for your boat, your anchor and your bottom. For example, a heavy-displacement hull with low windage and a keel may require substantially different tactics than a light flat-bottomed boat with a high superstructure. And a boat built for day trips may not have enough storage or weight-carrying capacity in the bow for heavy anchors and chain.

• Anticipate what the winds and current are going to do to your boat once you’ve settled in. If you don’t do this, the setting of the anchor may be just the beginning of a long, difficult night.

• If possible, always anchor in a spot where you have ample safe dragging room. We can’t always get it right.

Choose your weapons and hone your tactics. All you want to hear at night is the wind howling in the rigging, not the keel tearing on the reef.

February 2015 issue