Commonsense Anchoring - Soundings Online

Commonsense Anchoring

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Seamanship_1018

You’ve found the perfect spot to throw out your hook, but if your anchor doesn’t fetch up and set, and let your boat lay properly, then you can’t rely on it. And if you can’t rely on your anchor, then you — and nearby boaters — can’t relax.

Safety first. Everyone responsible for using the anchoring gear should be familiar with the boat’s equipment and routine. Every vessel is different. Anchoring antics are always entertaining for the rest of the anchorage, but to avoid being the focus of attention, poise and good habits are key. For new mariners, practice sessions will certainly carry the day. Whole books have been written on the subject of anchoring, but here are some basic, common-sense tips.

Photo of Pat Mundus

Pat Mundus

Make sure you have suitable ground tackle. Different types of anchors are best suited for anchoring in specific bottom types. Despite advertising claims, no single anchor design excels in all conditions. Know the kind of bottom conditions you will typically encounter, and use the right anchor for the job. In general, a wide, fluke-type of anchor like a Danforth, Bruce or Fortress works well in sand and mud, but not in thick grass. A Delta or Rocna can scoop and penetrate grass. Trickier yet is a rocky bottom, which, if you can’t avoid it, might demand a grapnel-type anchor and a reliable trip line. It’s a good policy to have a spare anchor on board in any case. Cruising boats carry several.

Visualizing the anatomy of your anchor and the catenary, or curve, of the rode, whether you use all-chain or nylon line, helps you set the anchor properly. The tips and flukes of an anchor penetrate and burrow in. The shank guides the flukes at the best angle as the rode pulls the anchor along and into the bottom.

No matter which type of anchor you use, the rode has to be long enough to keep the shank as parallel to the bottom as possible. If the rode is too short, then the shank will pull upward, the flukes will fail to penetrate, and the anchor will not fetch up properly.

When in doubt, let it out. Called scope, the amount of anchor rode varies with conditions. Minimum scope is a ratio of 3:1, or 3 feet of anchor rode to 1 foot of water depth (plus freeboard) for the most benign conditions. A 5:1 ratio is better if swinging room allows it. A ratio of 7:1 is ideal to achieve maximum holding power. Markers placed at intervals along the rode let you gauge how much scope has been let out. It’s a smart practice to let out more rode than necessary to set the anchor, and then shorten up to the correct scope after the anchor is set, especially in a crowded anchorage.

Seamanship_STRAIN_1018

Although heavy and harder to handle, all-chain rode sets an anchor well and adds holding power because it maintains the best low angle and adds weight on the bottom. When using chain, always know where hands, feet, hair, jewelry and clothing are relative to the chain. Mariners should practice with the bow arrangement and chain habits aboard each boat they handle. A nylon snubber line — a short, temporarily rigged length of nylon with a chain hook on its end — is recommended to transfer the load from chain rode to the boat after the anchor fetches up. The snubber line acts like a stretchy shock absorber and saves wear and tear on the anchor windlass.

Smaller boats often carry nylon rode instead of chain because nylon is light and easy to handle — but it does nothing to encourage the anchor shank to travel parallel to the bottom. To compensate for this drawback, and to guard against rode chafing on the bottom, a modest length of chain is shackled to the rode at the anchor. A thimble protects the nylon eye from chafe, and helps hold the shape of the splice. The thimble should be sized appropriately for the rode, spliced snugly into the eye to prevent shifting, and inspected occasionally for wear. Again, rode markers woven into the strands of nylon identify how much scope has been let out.

The chain and the anchor are married using shackles that should be sized appropriately for the chain, and tightened snugly. The pins should always be seized with stainless-steel wire to prevent loosening. On larger boats, a swivel is shackled between the anchor and chain to prevent chain twist. An all-chain setup is best suited for boats with an anchor windlass. Anchor windlass designs and capabilities vary, but generally speaking, the brake is released to let the anchor chain run out, and the windlass pulls the chain and the anchor back up.

Plan ahead. Pick a spot best suited for your anchor. Avoid poor holding ground like hardpan, rocky shelves or thick grass. The bottom type is on your charts; understand the symbols. Ask for local advice. Consult your chart or guidebook for designated anchorages, and do not anchor in or encumber a channel. Know the stage of the tide and the depth of the water so you know how much scope you’ll need. You want safe under-keel clearance to accommodate your draft at lowest tide, no matter which way you swing. What weather is predicted for your stay? Will there be set from tidal current? Answers to both questions will determine how your boat will lie once the anchor is set. Avoid underwater obstructions such as submerged pilings or wrecks. And of course, respect fellow mariners. Don’t crowd existing boats, and be mindful of your swinging radius: the sum of your boat’s length plus your rode.

After selecting your intended spot, maneuver into the wind or current (the stronger force of the two), place your bow where you want to drop anchor, and stop the vessel. After all way is off and only then, lower the anchor clear of the boat. Let the rode run out in a controlled manner, and back slowly away from it. Pay out the rode as you reverse. Do not drop a heap on top of the anchor. Instead, aim to lead the chain along the bottom. When the desired amount of rode is out, return to neutral and set the brake, or make the nylon rode fast (secure it to a cleat or bitts). Then slowly reverse the engine to put an intentional strain on the rode.

Three common things that will prevent the anchor from fetching up are trying to set the anchor on scope that is too short, reversing too abruptly, and failing to apply a reasonable strain on the anchor rode. Watching the shoreline or a fixed object can help determine a successful set. Study the chain or nylon. If the anchor drags instead of setting, the rode will visibly chatter instead of becoming taut. Paying out more scope may help it set. If not, heave up and try again. It happens to the best of us.

While anchored, keep an eye on your position. Prudent mariners take a couple of bearings on prominent, fixed landmarks and set the anchor alarm on the chart plotter, making any significant change in position immediately noticeable. At sunset, turn on the anchor light.

When it’s time to heave up and get underway, remove your anchor snubber, and review hand signals and windlass use. Anchor windlasses are not designed to pull the boat to the anchor. With a coordinated effort and hand signals between the skipper at the helm and the mate at the bow, the boat can be driven up handily to the anchor while chain or line is being retrieved. Use this method whether you use a windlass or not. Once the chain or nylon is “up and down,” most times the anchor can be tipped easily and pulled out of the bottom with a hard turn to port or starboard, and a burst of rpms with the windlass brake on or the anchor line made fast.

Bringing the anchor “home” (stowing it) is particular to each vessel. Secure your anchor in its bracket, roller, locker or hawse with the brake set, and sea lashings or safety pawls on, before proceeding to sea.

If you outfit your boat properly and use some common sense, your anchoring skills will become second nature.

This article originally appeared in the October 2018 issue.