Anchor
From the Simple English Wikipedia, the free encyclopedia that anyone can change
Anchors are used to stop boats from moving. Today, anchors are usually made of metal, and they are made to catch the ocean floor (the seabed).
There are two main types of anchors: temporary and permanent. A permanent anchor is called a mooring block and is not easily moved. A temporary anchor can be moved and is carried on the boat. When people talk about anchors, they are usually thinking about temporary anchors.
An anchor works by either weight (mass) or shape. Shape is more important to temporary anchors, and design is very important. Anchors must resist wind and tide, and also the up-and-down movement of waves.
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[change] History
The oldest anchors were just rocks, and many rock anchors have been found from a long time ago. Many modern moorings still use a large rock as the mooring block.
A simple anchor which uses two arms made of wood, and a rock weight, is an anchor which is still used today. The wood arms are sharp to enter the seabed, and the weight will hold normal movement.
[change] Designs of temporary anchors
The English language uses several special words to describe parts of anchors. This is because England has a rich marine and naval history, and so the language gives a large number of words to boat and ship terminology.
A modern temporary anchor usually has a middle bar called the shank, attached to a flat surface (traditionally called fluke) which holds the seabed. The place where the shank meets the fluke is called the crown, and the shank is usually fitted with a ring or shackle to attach it to the rode (cable, chain, or rope joining the anchor to the boat). Some old anchors have attached to the shank a stock, which is a bar that places the anchor in a certain way when it falls on the seabed. Old anchors are often named "stocked" or "stockless" anchors depending on whether they have this, or not.
There are many designs.
- Hook designs use small flukes with a heavy, narrow fluke-arms to go deeply into difficult seabeds.
- Plow (also spelled "plough") bury themselves in the bottom as force is applied to them. They look and work like a farmer's plow. The first was the CQR, first made in 1933 in the United Kingdom. They do not hold as well as modern anchors.
- Fluke or plate designs use large flukes to develop good holding. They hold well but are difficult to make set (go into the seabed).
Over the last 20 years, many new anchor designs have appeared. These anchors are usually designed for small vessels, and are usually not for large ships. See modern designs.
[change] Fisherman
The Fisherman is a traditional old design. It is very old and has not changed much over time. It is less useful than a good modern design, and its holding power for its weight is among the worst of all anchor types.
[change] Fluke
The most common brand of fluke anchors is the Danforth. The Danforth style uses a stock at the crown (see above), to which two large flat flukes are attached. The stock can rotate, so the flukes can move toward the bottom. It can hold very well but has difficulty setting (entering the seabed) on its own. It is efficient for its weight.
Fluke anchors have difficulty penetrating kelp and weed seabeds, as well as very hard sand or clay seabeds. Once set, the anchor can come free and fail to reset on its own.
[change] Grapnel
A traditional design, the grapnel style is simple to design and build. It is a simple hook, and while useless for most seabeds, it is good for rock or reefs.
[change] Plow
The original CQR was invented in 1933 in the United Kingdom. Many copies of it now exist. Plows used to be popular with sailors and private boaters. They are good but not excellent in most seabeds. Another more recent design is the Delta which is better.
Plows use a special weight in the tip of the fluke (the toe) for them to work properly. This makes them heavy.
The genuine CQR and Delta brands are now owned by Lewmar.
[change] Bruce / Claw
The genuine Bruce was invented in the 1970's and was intended to solve some of the problems of the plow. Many copies are now made - this type of anchor is now called a "claw-type". They can set quickly in some seabeds, but do not hold well for their weight, and can let go very suddenly.
Bruce Anchor Group no longer make the genuine Bruce and the copies are mostly worse in quality of build.
[change] Modern designs
Modern anchors are designed to be better than the plow and claw types. Many are new, still under patent and owned by commercial companies or tied to certain brands.
- The Bügel, first built by German steel company WASI, has a sharp fluke for weed, and features a roll-bar which turns the anchor to the right angle on the seabed
- The Bulwagga is a unique fluke style with three flukes instead of two. It has done well in tests by independent organizations such as American boating magazine Practical Sailor [1].
- The Spade is a French design which has been well accepted since 1996. It performs well [2].
- The Rocna is from New Zealand and has been made since 2004. It too has a sharp toe for weed and grass. It sets quickly [3], and has a large fluke area. Its roll-bar is similar to the Bügel's, and means the correct setting angle is reached without the need for extra weight to be inserted into the tip [4]. The Rocna got the highest averaged holding in SAIL magazine's testing in 2006 [1] [2] [3].
[change] Performance of temporary anchors
In general, the more modern designs are better than the older types, as can be seen from the chart on the left.
This is a chart of testing carried out by West Marine (an American marine shop) in 2006 [4]. Tests were conducted at three different locations on sand, at three different scopes (pull angles).
While six of the seven best anchors on this chart are "modern", several modern anchors are also seen to perform very badly. This demonstrates that 'newer' is not necessarily better.
[change] Designs of permanent anchors
These are used where the vessel or object is permanently placed, for example in the case of lightvessels or channel marker buoys. The anchor must hold the vessel in all weather, including the worst storm, but does not usually need to be moved.
Permanent anchors come in a wide range of types. A simple rock can be used. Large concrete blocks weighing many tonnes may be used. Modern moorings may be anchored by sand screws.
[change] Mushroom
The mushroom anchor is suitable where the seabed is composed of fine sand or soft mud.
It is shaped like a mushroom. It is a bit better than a simple weight, but not as good as a temporary anchor design of the same weight. They must be allowed to set by sinking over a long time.
[change] References
- ↑ Practical Sailor: "Anchor Reset Tests", Belvoir Pubs, January 2001
- ↑ Practical Sailor: "Anchor Tests Round 2", Belvoir Pubs, 1999
- ↑ Lowe, Colin: "Gear Test: Rocna Anchor", Boating NZ, July 2006
- ↑ Ginsberg-Klemmt, Erika & Achim, and Poiraud, Alain: "The Complete Anchoring Handbook", Ragged Mountain Press, 2007 (ISBN 0071475087)
- Edwards, Fred; Sailing as a Second Language: An illustrated dictionary, 1988 Highmark Publishing; ISBN 0-87742-965-0
- Hinz, Earl R.; The Complete Book of Anchoring and Mooring, Rev. 2d ed., 1986, 1994, 2001 Cornell Maritime Press; ISBN 0-87033-539-1
- Hiscock, Eric C.; Cruising Under Sail, second edition, 1965 Oxford University Press; ISBN 0-19-217522-X
- Pardey, Lin and Larry; The Capable Cruiser,; 1995 Pardey Books/Paradise Cay Publications; ISBN 0-9646036-2-4
- Rousmaniere, John; The Annapolis Book of Seamanship, 1983, 1989 Simon and Schuster; ISBN 0-671-67447-1
- Smith, Everrett; Cruising World's Guide to Seamanship: Hold me tight, 1992 New York Times Sports/Leisure Magazines
[change] Other websites
- "Ultimate Holding Power" - Anchor Test from Yachting Monthly December 2006
- "Holding Power" - 14 Anchors Tested from SAIL magazine October 2006
- Lightship anchors
- About the Manson Supreme Anchor — Article discussing problems with copies of genuine anchor types
- A Process of Evolution — An essay on boat anchors by New Zealand boatbuilder, offshore cruiser, & consultant Peter Smith
- The Bottom Line: Anchoring In 2007 — Article on anchoring from Coastguard Member's Handbook 2007
