Perm Moorings

From the Sea Scout manual: Safety and Seamanship 169

The chain used in permanent moorings is standard link steel chain that is usually galvanized to resist corrosion. The diameter should be large enough for a holding power consistent with the strain that will be placed on it. Some two-thirds of the total length of chain to be used should be of heavy chain (¾ to 1 inch in diameter). The balance should be lighter. The chain and all fittings should be checked annually for any possible looseness or worn links. The mooring buoy that the light chain connects to is often Styrofoam. If a metal buoy is used, it should have some form of a bumper to cushion any possible striking against the boat’s hull. The pendant or line by which a boat is connected to the mooring buoy should be about the same strength as the chain and often is made of Manila or nylon. Nylon is good for several seasons; Manila should be replaced each year. As the pendant will run through the bow chock at angles depending upon the swinging of the boat, the edges of the chock should be smooth to minimize any abrasions. The pendant itself should be protected by tape, cloth, canvas, or a hose tied around it to protect it from chafing where it rubs along the chock. The pickup buoy can be made of many things. Whatever the material, it should have a ring or handle on top to aid in picking it up.

A mooring anchor should be of the mushroom type in muddy or sandy bottoms. There should be a bulb on the upper end of the shank to help keep the anchor down in a digging position.

(Mushroom Anchor for our area of sandy bottom Jamica Bay)

A common rule of thumb for mushroom anchor weights is about 10 pounds for every foot of the boat’s overall length. This may be lessened somewhat for small, lightweight racing sailboats, but should be increased for larger cruising craft, both power and sail. In hard or rocky bottoms, other types of moorings with sufficient weight would be adequate.

(For the SSS Striper, its length is 21ft. , so we need a 210 lb Mushroom) the 200lb is fine.

Discarded railroad wheels, concrete blocks, old engine blocks, etc., might make adequate permanent mooring anchors, but in really bad storms, the mushroom anchor is the most effective anchor.

(We are mooring in 12ft. (average) of water, so heavy chain length would be 1 ½ times the depth)

Two sections of galvanized chain: a heavier, primary chain and a lighter, secondary chain. The primary (ground) chain lies on the bottom. Its length should be 1 1/2 times maximum water depth.

(So 12ft, would be 12’+6’ would = 18’ of heavy 1”chain)

The secondary (riding) chain, is connected to the ground chain with a galvanized shackle or swivel. It's usually half the diameter of the ground chain and equal in length to maximum water depth.

(For secondary chain, is ½” chain, our depth is 12’, so an additional 12’ of chain). Total chain length would be 30ft.

Mooring Buoys

Allow you to pass the chain through the center of the buoy and attach the pendant on top. Secure the mooring chain at the top using a 4" galvanized O-ring.

The buoy must have about twice as much flotation as the suspended chain has weight in order for it to ride high enough in the water to be visible. 

 Mooring Pendant

The pendant (pronounced “pennant”) attaches the chain to the boat. Large-diameter three-strand nylon line is used because its inherent elasticity (stretching about 10 percent under a load equaling 20 percent of its tensile strength) allows it to act as a shock absorber. Polyester line, Dyneema line or stainless steel wire is preferred by some for better chafe resistance. Length should be about 2 1/2 times the boat's freeboard. Diameter should be as large as is practical—but it must be able to fit through bow chocks and around a bow cleat.

(For the 21ft Striper, we have 4 ft. of freeboard, so our Pendant lines would be 10ft each).