3.3 Ground Tackle & Anchoring

Ground Tackle Defined

Ground tackle is the whole anchoring system: the anchor, the rode (the line and/or chain connecting anchor to boat), and the connecting hardware - shackles, swivel, and thimble. Good ground tackle, correctly used, is a safety system; it holds you off a lee shore when the engine quits and lets you ride out weather. The exam tests both the gear and the technique.

Anchor Types and Their Bottoms

No single anchor is best everywhere - holding depends on matching the anchor to the bottom (holding ground):

• Fluke / Danforth - lightweight, with large flat flukes that dig into sand and mud. Superb holding-to-weight in those bottoms and stows flat, but sets poorly in rock, grass, or weed and can pull out if the wind clocks around and changes the pull direction.
• Plow (CQR) and Delta - a single plowshare that buries itself and resets as the pull direction changes. Versatile across sand, mud, and grass; heavy and stows on a bow roller.
• Claw (Bruce) - sets quickly and holds in sand, rock, and coral, forgiving of a poor initial set, though its holding-to-weight is lower than a fluke's.
• Mushroom - a heavy bowl used for permanent moorings in soft bottoms, where it slowly beds in; useless as a working anchor.
• Grapnel - hooks rock bottoms and retrieves small craft moorings.

Good holding ground is firm sand, mud, or clay; poor holding ground is rock, shale, loose shells, or grass.

Choosing an Anchorage

Before the anchor ever goes down, pick the spot well. A good anchorage offers protection from the prevailing wind and sea, good holding ground (check the chart's bottom notation - "S" sand, "M" mud), adequate depth at low water, and enough room to swing. An anchored boat lies to her rode and swings in a circle as wind and current shift; the radius of that circle is roughly the rode length plus the boat's length, and you must be sure that circle clears shoals, other anchored boats, and the shore through a full change of tide. Anchor with enough distance from your neighbors that your swing circles do not overlap, and remember that boats of different types (a deep sailboat versus a light powerboat) swing differently to the same wind.

The Rode and the Chain Leader

The rode is what connects anchor to boat. It may be all chain (heavy, chafe-proof, and its weight helps hold the pull horizontal) or, more common on small craft, a combination rode of nylon line with a length of chain shackled between the line and the anchor. That chain leader does three jobs: it keeps the pull on the anchor horizontal, it resists chafe where the rode drags over rock or shell, and its weight adds a shock-absorbing sag (catenary). Nylon's stretch then absorbs surge. A typical setup is 6 to 20 feet of chain plus enough nylon for full scope.

Scope: The Heart of Anchoring

Scope is the ratio of the length of rode paid out to the vertical distance from the bottom to the bow chock - that is, water depth plus the height of the bow above the water (and you must account for the height of tide at high water). The standard working scope is 7:1: seven feet of rode for every foot of that vertical distance. In calm conditions with limited swinging room you might use 5:1; in a storm you veer to 10:1 or more.

Scope matters because an anchor holds by a horizontal pull that keeps the flukes dug in. With generous scope, the rode leads out at a shallow angle and the pull on the anchor shank is nearly horizontal, so it bites. With too little scope, the rode angles steeply down, lifting the shank and breaking the anchor out of the bottom - the boat drags. More scope equals a flatter pull equals better holding.

Worked example. You anchor where the charted depth plus the height of tide will be 15 feet at high water, and your bow chock stands 5 feet above the water. The vertical distance is 15 + 5 = 20 feet. At 7:1 scope you pay out 7 x 20 = 140 feet of rode. Setting out only 60 feet here would give barely 3:1 - a near-vertical pull that will not hold.

Setting the Anchor

Approach the chosen spot heading into the wind or current. When the bow reaches the spot, lower the anchor - never heave it, which fouls the rode on the flukes. As the boat drifts back, pay out rode steadily so it lays along the bottom rather than piling on the anchor. At full scope, snub the rode on a cleat and back down gently with the engine in reverse; feel the anchor dig in and stop the boat. If it drags, retrieve and try again or move to better bottom.

Checking for Drag and Weighing Anchor

Once set, confirm you are holding. Take ranges (two fixed objects in line) or compass bearings on shore features and watch whether they change; a GPS anchor alarm does the same electronically. Sudden changes, a rode that goes slack then snaps taut, or a vibrating rode signal dragging - veer more scope, re-set, or move. Post an anchor watch in bad weather. At night, an anchored vessel shows an all-round white anchor light; by day it shows a black ball shape forward (this ties directly to the Rules of the Road). To weigh anchor, motor slowly up to the anchor while hauling in the slack, break it free when the rode is straight up-and-down, and if it is fouled on an obstruction use a trip line rigged to the anchor's crown to pull it out backwards.