Anchors – Anchoring Techniques
The anchors that were in use for ship moorings up to the beginning of the last century consisted of a long, round iron shank, having two comparatively short, straight arms, or flukes. These were inclined to the shank on the anchors at an angle of about 40 degrees, and met it in a sharp point at the crown. The larger ship anchors had a bulky wooden stock which was built up of several pieces, the whole tapering outward to the ends, especially on the cable side. Since then there have been several modifications to anchor design, including the introduction of slightly bowed arms in order for more effective mooring and a change to more durable material.
● Danforth/Fortress: This type of anchor is one of the best anchors for holding in many different types of bottom composition. It weighs less than other anchors yet holds better due to its design. These anchors usually perform better when a short length of chain is used as a leader before the rope is attached. Yachtsmen's or Navy type Anchor: This style of anchor is best suited for soft bottoms. It is one of the oldest anchor designs and is considered by some to be obsolete. This type of anchor uses weight in its design to help it dig into the bottom.
● Grapnel Type: This style of anchor works much like a grappling hook. It takes hold of debris or rocks at the bottom. It is ineffective on muddy or sandy bottoms but works fairly well out at the jetties. Be prepared to loose this anchor though. Mushroom anchor: This is the choice of many fishermen.It is the easiest anchor to use and works well in many bottom situations. It is very affordable takes up little room to stow. It is an excellent choice for back bays and calmer waters. One drawback of the mushroom anchor is that it often looses its hold in windy or strong current conditions.
● Sea Anchor: This anchor doesn't use the bottom to hold the boat in position but rather uses the water. It looks like an oversized windsock and is used to control a boat's drift in high wind situations. The sea anchor is a handy device to have on board. It can be used to control your drift while drift fishing. It also can save your life in stormy conditions by holding your boats bow into the wind, when other anchoring methods fail.
Anchoring and Scope - Here are some basic anchoring guidelines:
Make sure that you use an anchor designed for the type of bottom primarily encountered in your boating area. Even with a small vessel, five or six feet of chain is desirable. Shackle the chain to the anchor. Put a thimble on the end of the anchor line and shackle that to the other end of the chain.
Chose your anchor line carefully. A line that is too heavy will actually cause problems because you’ll loose the "elasticity" that absorbs the shock and keeps the anchor well set. Pick your anchorage carefully. If there are other boats nearby, you will need to "guess" at their potential swing. A boat on a mooring will have very little swing but a vessel at anchor may have considerable "scope" out and may swing widely. A shallow draft boat will be more affected, usually by the wind whereas a deep draft boat will be more affected by the current. Put your bow into the wind or current (whichever is having the greatest affect on your boat), power up slowly to or just beyond where you want your anchor to lie (keep your anchor scope in mind) and check your forward motion with your reverse gear. Double check to ensure that the end of your anchor line is attached to something sturdy on the boat. Most experienced boaters have watched at least one anchor with line disappear over the bow because they forgot to secure the end. Don’t throw the anchor – it might get tangled. Release it by holding on to the chain or line, making sure that the chain and line are free, and dropping the anchor off the bow.
Once you see slack in the line, feed out the proper amount of scope as the boat drifts back. Average "recommended" scope is about 7 to 1 – that means that if you are in 10 feet of water you will want to pay-out about 70’ of line. You also want to take into consideration the distance between the water line and the bow cleat and also any depth increase because of tides. If the tide may come in another 2 feet and your bow cleat is 2 feet above the water, you are, effectively, in 14 feet of water and would need to pay out around 100’ of line. Up to 15 to 1 scope may be necessary in strong winds or currents.
Once the scope is out, secure the line (cleat and chock) and "back down" on the anchor keeping your bow into the wind/current. Idle speed is usually sufficient to make the anchor "bite" into the bottom and "set." Put the engine in neutral and get your "bearings." Find two points on each beam that form a natural "range" or line and a third either ahead or astern from which you may be able to judge distance. They can be other anchored boats, rocks, buoys or points on land. Sit there for a few minutes to make sure that none of the angles or distances to these points change. Any change would indicate that you are dragging and need to reset your anchor or pay out more scope – or both.
Chain Anchor Rode
The chain is marked according to the shot. After the first shot from the anchor, the detachable link is painted red and one link on each end is painted white. One turn of wire is placed on the outboard white links. After the second shot, the detachable link is painted red and two links on both sides of the detachable link are painted white. Two turns of wire are placed on the outboard white links. This marking is continued throughout until the second to last shot is reached. The second to last shot is entirely yellow. The last shot is entirely red. The bitter end should be made fast with a weak link to a cleat or pad-eye.
Glossary of Terms
Abrasion - frictional surface wear on the wires of a wire rope.
Back Stay - wire rope or strand guy used to support a boom or mast.
Below-the-Hook Lifting Devices - devices used to attach the load to the hoisting gear below the hook.
Birdcage - description of the appearance of a wire rope forced into compression. The outer strands form a cage and, at times, displace the core.
Block - a wood or metal case enclosing one or more sheaves provided with a hook, eye, and strap by which it is attached to an object. They are designed to provide mechanical assistance when moving large heavy objects. Blocks can be named by the number of sheaves, location, or function.
Block and Tackle - the complete unit of two or more blocks rove up with an adequate amount of rope.
Boom - a spar or pole projecting from a mast for supporting or guiding the weights to be lifted.
Bull Rope - a wire rope or fiber line used to heave, haul, or lift a load without benefit of the multiplying power of tackle blocks.
Cargo Gear - includes masts, stays, booms, winches, cranes, standing and running gear, slings, pallets, spreaders and similar loose gear, as well as vangs, preventers, and the tackle and structures forming part of the shipboard cargo gear used in connection with the loading and unloading of a vessel.
Come-a-Long - device for making a temporary grip on a wire rope.
Core - center component of a wire rope which the strands are laid around. It provides support for the outer strands.
Corrosion - chemical decomposition of metal wires in a rope, or rigging due to moisture, acids, alkalines or other destructive agents.
Corrugated - term used to describe the grooves of a sheave or drum after they have been worn down to a point where they show an impression of a wire rope.
Cover Wire - outer most layer of wires.
Crane - mechanical device intended for lifting or lowering a load and moving it horizontally, in which the hoisting mechanism is an integral part of the machine. A crane may be a fixed or mobile machine.
Derrick - a mechanical device intended for lifting, with or without a boom supported at its head by a topping lift from a mast, fixed A frame, or similar structure. The mast or equivalent member may or may not be supported by guys, or braces. The boom, where fitted, may or may not be controlled in the horizontal plane by guys (vangs).
Dog-Leg - permanent bend or kink in a wire rope, caused by improper use or handling.
End Fitting - the treatment at the end of wire rope, usually made by an eye or an attached fitting. Designed to be the permanent end on wire rope which connects to the load.
Eyebolt - a bolt having either a head looped to form a worked eye, or a solid head with a hole drilled through it forming a shackle eye.
Fall - part of the rope of a tackle to which power is applied.
Fitting - used to attach different components to each other and to the ship.
Gantry Crane - crane having a spanning framework, often set on tracks and used for loading/unloading containers.
Gooseneck - An iron swivel making up the fastening between a boom and a mast. It consists of a pintle and an eyebolt or clamp.
Guy - wire rope, fiber line, or chains that support booms, davits, etc. laterally.
Guy Pendants - pendants that connect the head of the boom with a guy tackle and serve to shorten the length of the guy tackle.
Fiber - smallest component of a Manila line.
Filled Sockets (poured sockets) - sockets that use molten metal (such as zinc) to secure them to the wire rope.
Heel Block - a block located at the foot of a boom and fastened to a mast or kingpost. One of the blocks through which the main cargo fall is reeved.
Hook - comes in two classes: plain hook and self mousing hook. The four basic parts of a hook are the eye, throat, mouth, and pea. A self mousing hook also has a spring loaded lever attached to it that cover the mouth of the hook.
House Falls - spans and supporting members, winches, blocks, and standing and running rigging forming part of a marine terminal and used with a vessel's cargo gear to load or unload by means of married falls.
Kink - irrepairable deformation in wire rope caused by a loop of rope being pulled down tight, greatly reducing the rope strength.
Lay - (a) "rope lay" signifies the direction of rotation of the wires and the strands in the rope. (b) "lay length" is the distance measured along the rope in which a strand makes one complete revolution around the rope axis.
Line - length of fiber or wire rope that transmit pulling forces.
Loose Gear - removable and replaceable components of equipment or devices which may be used with or as part of assembled material handling units for purposes such as making connections, changing line direction and multiplying mechanical advantage. Examples are shackles and snatch blocks.
Mousing - covering the mouth of a hook to prevent cargo from slipping off when the line holding it slacks.
Outriggers - extendable or fixed metal arms, attached to the mounting base of a crane, which rests on supports at the outer ends. Used to increase support by spreading the weight of the crane and load over a wider base.
Padeye - a fitting having an eye integral with a plate or base in order to distribute the strain over a greater area and to provide ample means of securing. The pad may have either a "worked" or a "shackle" eye, or more than one of either or both.
Peening - permanent distortion resulting from cold, plastic metal deformation of the outer wires of a wire rope.
Pendant - a hanging length of rope having a block or thimble secured to its free end.
Ply - component of synthetic line made of yarns twisted together. Plys are twisted together to form strands.
Preventers (guys and stays) - heavy wire rope used to supplement the regular guys and stays as a safety precaution when handling cargo.
Reeve - passing the bitter end of a rope or line through a block or series of blocks.
Rigging - generic term that is used to describe the ropes, lines, blocks, etc. that are used to support and move an object.
Runner - a tackle or part of a tackle consisting of a line rove through a single block and fixed at one end.
Running Rigging - rigging that is reeved through blocks or fairleads, used to move cargo gear or load.
Safe Working Load (SWL) - is the load the gear is approved to lift, excluding the weight of the gear itself.
Schooner/Midship Guy - the tackle that spans the ends of two booms.
Sheave - a grooved pulley for wire rope.
Sling - a rope, chain, net, etc. used in hoisting freight.
Splice - joining of two sections of rope or line by interweaving of the strands.
Standing Rigging - rigging remaining permanently in position.
Strands - for Manila line, made of yarns twisted together. Three strands are laid up or twisted to form a line (plain laid line). For synthetic line, made of plys twisted together. Strands are laid up or twisted to form the line. For wire rope, strands are formed by twisting wires together. Strands are then laid around a core to form the wire rope (most wire rope consists of 6 strands wrapped around a core).
Swaged Fitting - fitting which wire rope can be inserted and then permanently attached by cold pressing (swaging) the shank that enclosed the rope.
Tackle - any combination of ropes and blocks that multiplies power.
Thimble - grooved metal fitting to protect the eye, or fastening loop of a wire rope.
Topping Lift - tackle that support the head of a boom.
Union Purchase - an arrangement in which a pair of booms is used in combination, the booms being fixed and the cargo runners coupled.
Valley Break - Break on the valley between strands on wire rope.
Whip - a tackle consisting of a fall rove through a single standing block (single whip) or of a fall secured at one end and rove through a single running and a single standing block (double whip).
Winch - a power driven spool for handling of loads by means of friction between fiber or wire rope and the spool.