How to Choose a Boat Anchor: Types, Holding Power & Sizing by Boat Length

Few things wake a boater faster than the feeling of the hull swinging the wrong way at two in the morning, the anchor dragging across the bottom. The best anchor is not the heaviest or the most expensive one. It is the one matched to the seabed you drop it on and sized correctly for your boat. Get those two things right and you will sleep through the night. This guide covers the main anchor types, how holding power works and how to size ground tackle to your boat.

Match the Anchor to the Bottom

Every anchor is a compromise, and the single biggest factor in whether it holds is the type of bottom you are setting into. Before you look at brands or weights, think about where you actually anchor most often. The table below is a quick starting point.

Most boaters keep a primary anchor suited to their home waters and a second anchor of a different type for everything else. That second anchor is what saves the day when you drop the hook somewhere new and the bottom is not what you expected.

The Main Types of Boat Anchors

Fluke (Danforth Style)

The fluke anchor, often called a Danforth after the classic design, uses two long flat blades hinged to a shank. It sets quickly in sand and mud, delivers excellent holding for its weight and stows flat against a bow roller or in a locker, which makes it a favorite second anchor even on boats that carry something else on the bow. It is less at home in grass or rock. Go2Marine carries traditional Danforth-style fluke anchors as well as the lightweight aluminum Fortress anchors, whose adjustable fluke angle can be set for soft mud.

Claw

The claw anchor, modeled on the original Bruce design, uses three curved tines to scoop into the bottom. Its strength is versatility: it sets easily across sand, mud and rock, and it resets well after a wind or tide shift swings the boat. The trade-off is holding power per pound, which is lower than a fluke or a modern scoop, so claws are usually sized up a notch. For boaters who anchor in varied conditions and value a fuss-free set, a claw is hard to beat and you will find galvanized claw anchors in the anchors collection.

Modern Scoop and Next-Generation Anchors

The newest generation of anchors uses a concave, shovel-like fluke, and many add a roll bar or weighted tip that flips the anchor upright and drives it into the bottom the moment it lands. The result is fast setting and strong, deep holding across nearly every bottom type, including the grass and weed that give older designs trouble. They cost more and need a compatible bow roller, but for a primary cruising anchor they are the modern benchmark. Go2Marine stocks respected next-generation designs including Rocna and Mantus anchors.

Other Types You Will Hear About

A few other designs come up in conversation. The plow anchor, a long single blade that buries like a farm plow, has served cruising boats for decades and remains popular, though the newer scoop designs have largely overtaken it on holding tests. The grapnel, with its folding hooks, is a small-boat and dinghy tool for grabbing rock or structure. The mushroom anchor relies on suction and sheer weight and belongs on a permanent mooring, not on the bow of a boat you actually anchor and retrieve.

What Holding Power Actually Means

Holding power is simply the force it takes to drag an anchor out of the bottom, and it is the number that really matters when the wind pipes up. It depends on four things working together: the anchor design, its weight, the type of bottom and how much rode you let out. A well-designed anchor that has buried itself deep in firm sand can hold many times its own weight, while the same anchor lying on its side in grass holds almost nothing. That is why setting technique and scope matter as much as the anchor itself, and why manufacturer holding figures are best treated as ideal-condition numbers rather than guarantees.

Sizing Your Anchor by Boat Length

Anchor sizing starts with boat length but does not end there. A light, high-sided runabout and a heavy trawler of the same length catch the wind differently and need different anchors, so displacement and windage matter too. The chart below gives a general starting point for a primary anchor in average holding ground and moderate conditions. Always confirm the exact model against the manufacturer's sizing chart for your boat's length and displacement, and step up a size for exposed anchorages or overnight security.

Two notes on the chart. Aluminum flukes such as the Fortress achieve comparable holding at a lighter weight, so their sizing runs lower than the figures above. And these ranges assume a modern anchor design; an older claw may want the next size up. When in doubt, err heavier, because the penalty for an oversized anchor is a little extra weight while the penalty for an undersized one is a dragging boat. Browse the full range in the anchors collection to compare weights across designs.

The Rest of the Ground Tackle

An anchor is only one part of the system that keeps your boat in place. The complete package, called ground tackle, includes the rode that connects the anchor to the boat, the hardware that joins it together and a way to retrieve it all.

• Rode. This is the chain, rope or combination that runs from anchor to boat. A length of chain at the anchor end adds weight, resists chafe on the bottom and helps the anchor set at a better angle. Shop chain and rope in the anchor chain and anchor lines collections.

• Connecting hardware. Shackles and swivels join the anchor to the rode and let it align as the boat swings. Match the hardware rating to your tackle in the chain links and swivels collection.

• Retrieval. On larger boats a windlass takes the strain out of raising ground tackle, running over a bow anchor roller that guides the rode and secures the anchor. See options in the windlasses and parts collection, and read our guide to choosing your windlass before you buy.

One rule ties the system together: scope. Let out about seven feet of rode for every foot of water depth, measured from the bow, as a working standard. You can shorten to five to one in calm, crowded anchorages and should lengthen toward ten to one when it blows. Our anchoring guide walks through setting the hook step by step.

Setting the Anchor So It Holds

Even the right anchor will drag if it is set poorly, and setting one well takes only a minute. Motor slowly up to your chosen spot, head into the wind or current, and bring the boat to a stop. Lower the anchor to the bottom rather than throwing it, then let the boat drift back as you pay out rode to the scope you need. When enough rode is out, snub it off and let the anchor dig in, then gently increase reverse throttle to drive it into the bottom and confirm it is holding. Pick two points ashore that line up and watch them: if they stay put, you are set. Our anchoring guide covers the full technique in detail.

Getting the anchor back up is the reverse. Motor slowly forward toward it while taking in rode so the boat, not your back, does the work, then break it free by pulling straight up once you are directly above it. If it is fouled on an obstruction, easing the boat in a slow circle often frees it. A bow anchor roller makes both dropping and retrieving cleaner and protects the hull.

Anchoring Overnight and in Heavy Weather

Day anchoring in a quiet cove and riding out a blustery night are very different jobs, and your ground tackle should reflect that. For overnight or storm anchoring, let out more scope, closer to ten to one, so the pull on the anchor stays low and horizontal. Adding weight low on the rode, with more chain or a dedicated weight, keeps the angle flatter still and dampens the boat snatching in gusts. This is where a larger primary anchor earns its keep, and why many cruisers carry a second, heavier storm anchor for when the forecast turns. Matching heavier anchor chain to the conditions gives the whole system more holding and more peace of mind.

Choosing Your Anchor in Four Steps

1. Identify your usual bottom. Sand, mud, grass, rock or a mix. This drives the type more than anything else.

2. Pick a type that suits it. A fluke for sand and mud, a claw or scoop for versatility, and ideally a second anchor of a different type for the unexpected.

3. Size it by length and displacement. Use the chart as a starting point, confirm against the manufacturer's chart, then step up for security.

4. Match the rode, hardware and windlass. The anchor is only as good as the tackle and the scope behind it.

Work through those four steps and you will end up with an anchor you trust. Start comparing designs and weights in the anchors collection at Go2Marine, and remember that carrying a primary anchor plus a backup of a different type is the surest way to hold, wherever you drop the hook.