Perhaps this seems like going back to school, but procedure can be critical in soft mud, and I’ll wager most old cruising hands from soft mud areas do it about the same way. Don’t be the gump that just dumps the anchor along with 50 feet of chain and goes below to mix a drink, or the other gump that lowers the anchor, insufficient scope, and then proceeds to plow furrows all over the bottom, proclaiming the holding is poor or his anchor lame. Few things identify an experienced cruiser more obviously than solid anchor placement technique.
Just how soft is the mud? The sounding lead method, armed with grease will show you what is in the top 1/8-inch but not much more. The US Navy used to have a practice where they would send couple guys out in a small boat with a blunt stake and a hammer:
- Very dense sand: more than 50 blows/foot.
- Sand: 25-50 blows/foot.
- Hard clay: more than 16 blows/foot.
- Consolidated mud/clay: 4-16 blows/foot.
- Soft mud: 2 blows/foot.
- Very soft mud/silt: you don’t need the hammer.
My variation is to use either a long boat hook or kayak paddle. If I can push it in more than 18 inches with one hand with only it’s hopeless. If I can push it in 1-foot with one hand while reaching well out to the side (15-20 pounds) I will need to be careful. Less than that, anchor as usual. I also look at the stuff that comes up with the paddle; sticky is good, if it rinses off on the way up, that’s bad.
Maneuvering, Step by step
- Bring the boat into the wind over the target location and stop.
- Allow the boat to begin drifting to leeward at about 0.5-knot. If there is insufficient wind to cause this naturally, apply just a touch of reverse for a few seconds.
- Lower the anchor until it just touches the bottom, adding a few more feet at a time as the chain begins to angle forward, away from the boat. The goal is to place the anchor right side up, with the fluke facing aft, and gently tip it over. Since most modern anchors will line themselves properly as a result of the water flow when backing slowly, this procedure should land the anchor butter side up, facing the correct direction, and without chain tangles. Even roll-bar anchors can get stuck on their backs in soft mud, the ooze providing insufficient resistance to right them. Continue to add chain very slowly until the angle is at least 60 degrees.
- Lower the required amount of chain more quickly. It doesn’t matter if the boat drifts downwind at an odd angle during this step.
- Attach the snubber before the chain draws tight to avoid a potentially damaging jerk on the windlass. Place chafe gear on the snubber.
- The boat is moving very slowly aft prior to snubbing and the anchor will take a light bite, gently stopping the boat. However, the anchor is not set.
- If anchoring in very soft mud, allow the anchor to settle for 10 or 15 minutes. The exception to this rule is the Fortress anchor, which should be set more quickly and on short scope; the shank tends to sink faster than the aluminum flukes, which once point up, may be unable to catch. The mud palms normally solve this problem, as does getting the initial “catch” on shorter scope. Light chain also helps; a Fortress in soft mud is no place for BBB chain.
- Apply reverse at idle, backing at no more than 1-knot until all of the slack is removed from the chain and snubber. Note the GPS coordinates to the nearest 0.001-minute. This is about 6 feet. Speed should be zero after the slack is taken up.
- Very slowly increase reverse throttle from idle to the maximum intended over a period of 3-5 minutes in very soft mud. Although the GPS may display a speed of 0.5-1 knots for no more than 5-10 seconds, returning to zero before full power is reached. This is the result of controlled anchor drag during setting (typically 8-15 feet in soft mud), straightening of chain catenary, and snubber stretch. Again, note the GPS position.
- If the anchor takes more than about 20 feet (0.003 minutes latitude/longitude) to set, it is not actually setting. It’s probably upside down or fouled. If it does seem to catch, it is probably just caught on trash. Raise the anchor all the way so that you can check for fouling, and repeat from step one. If the mud is very soft, wait 1-hour before the initial power set, and then use only 25 percent power.
- Secure the rode by means of a chain stopper or cleat as a back-up, in case of snubber or non-locking chain hook failure.
- Cut the engine. If severe weather is predicted, consider what we have learned about cyclical loading and plan on power setting again in a few hours; again, a slow increase from idle to full throttle over about 3 minutes.
Some have suggested letting the rode go slack and then backing up hard to confirm that the boat stops abruptly, but we can’t recommend that, since it is far too easy to generate huge forces, reduce the soil consolidation, and invisibly undo what you have achieved.
Like driving a nail into wood, a proper stroke is always more efficient than the sloppy bashings of a teenager. Lay the anchor down carefully, lay the chain out carefully, power set appropriately, and your problems will be few.Anchor Test Archives Yield Rich Data on Mud
In the summer of 2014, Fortress Anchors, the maker of a popular aluminum Danforth-style anchor, conducted a series of anchor-holding tests in Chesapeake Bay, an area renowned for its soft mud and oyster-shell seabed. Its aim was to examine the performance of its products against some of the newer anchor designs introduced since the companys previous head-to-head tests (see “Anchoring in Squishy Bottoms,” PS February 2015.
Practical Sailor carried out its own series of anchor tests in a mud bottom in 2006 (see April 2006 and October 2006 issues), and those tests bore out a commonly known fact: Danforth-style anchors, which feature flukes that are proportionally larger than other types of anchors of the same mass, tend to hold better than older, plough-style anchors in soft mud.
These tests and others are curated in Volume 1, “Anchoring in Sand and Mud,” the first part of of our four volume series on anchoring at www.practical-sailor.com/products.