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An anchor is an object, often made out of metal, that is used to attach a ship to the bottom of a body of water at a specific point. There are two primary classes of anchors—temporary and permanent. A permanent anchor is often called a mooring, and is rarely moved; it is quite possible the vessel cannot hoist it aboard but must hire a service to move or maintain it. Vessels carry one or more temporary anchors which may be of different designs and weights. A sea anchor is an unrelated device: a drogue used to control a drifting vessel.

The vessel is attached to the anchor by the rode which is made with chain, cable or line or a combination of these. The hole in the hull through which the anchor rode passes is called "hawsepipe" because thick mooring lines are called "hawsers".

An anchor works by resisting the movement force of the vessel which is attached to it. There are two primary ways to do this—via sheer mass, and by "hooking" into the seabed. While permanent moorings can use large masses resting on this seabed this is not practical for temporary anchors which need to be stowed onboard so almost all temporary anchors are of the type which have metal flukes which hook on to rocks in the bottom or bury themselves in soft bottoms.

An interesting element of anchor jargon is the term aweigh, which describes the anchor when it is hanging on the rope, not resting on the bottom; this is linked to the term to weigh anchor, meaning to lift the anchor from the sea bed, allowing the ship or boat to move. An anchor is described as aweigh when it has been broken out of the bottom and is being hauled up to be stowed. Aweigh should not be confused with under way, which describes a vessel which is not moored to a dock or anchored, whether or not it is moving through the water. Thus, a vessel can be under way (or underway) with no way on (i.e., not moving).

Contents

Development

See full article: History of the Anchor.

The earliest anchors were probably rocks and many rock anchors have been found dating from at least the Bronze Age.[1] Many modern moorings still rely on a large rock as the primary element of their design. However, using pure mass to resist the forces of a storm only works well as a permanent mooring; trying to move a large enough rock to another bay is nearly impossible.

Designs of temporary anchors

A modern temporary anchor usually consists of a central bar called the shank, and an armature with some form of flat surface (fluke or palm) to grip the bottom and a point to assist penetration of the bottom; the position at which the armature is attached to the shank is called the crown, and the shank is usually fitted with a ring or shackle to attach it to the cable. There are many variations and additions to these basic elements—for example, the whole class of anchors which include a stock such as the fisherman and fluke anchors.

The range of designs is wide, but there are actually trends in designs for modern anchors which allow them to be classed as hook, plough, and fluke types, depending on the method by which they set.

  • Hook designs use a relatively small fluke surface on a heavy, narrow arm to penetrate deeply into problematic bottoms such as rocky, heavy kelp or eel grass, coral, or hard sand. Two of the more common versions of this design are the fisherman and the grapnel.
  • Plough designs are reminiscent of the antique farm plough, and are designed to bury themselves in the bottom as force is applied to them, and are considered good in most bottom conditions from soft mud to rock. North sea designs are actually a variation of a plough in how they work; they bury into the bottom using their shape.
  • Fluke designs use large fluke surfaces to develop very large resistance to loads once they dig into the seabed. Although they have less ability to penetrate and are designed to reset rather than turn, their light weight makes them very popular.
  • Drogues and sea anchors simply use the water itself as a weight, hereby allowing the "anchor" to consist of merely a canvas and a rope (to hold the textile in place).

In the past 20 years or so, many new anchor designs have appeared. Driven by the popularity of private pleasure boats, these anchors are usually designed for small to medium sized vessels, and are usually not appropriate for large ships. See modern designs.

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Fisherman

A fisherman's anchor

A traditional design, the fisherman, also known as a kedge (not be confused with a modern-day light kedge anchor), is the most familiar among non-sailors. The design is a non-burying type, with one arm penetrating the seabed and the other standing proud. The anchor is ancient in design and has not changed substantially over time.

It has a good reputation for use in rock, kelp and grass. On soft grounds it is important that the anchor has large flukes. Even with large flukes, it has less holding power to weight ratio than modern anchors. It is a good all around anchor for those who need to anchor on all types of seabed. However, if anchored under conditions where the boat can drift over and around the anchor (light, changing wind and tides), the anchor is easily fouled by the chain and the anchor loses its holding power. Under these conditions, the anchor needs to be brought to surface and checked before it can be trusted in any but light conditions.

The fisherman anchor is more difficult to stowe than modern ones, as it does not stow in a hawse pipe or over an anchor roller. The foredeck and rail must be designed specifically and an anchor stick must usually be employed not to get the topsides scarred. This must be done in a proper manner as to avoid damage; typically, on anchors over 50 or 75 kg, this is a two man job. Most versions include a folding stock so the anchor may be stowed flat on deck. Some are also made with hinged flukes and some in 3 pieces and can thus be stowed in a locker.

A fouled kedge or killick features on the badges of Royal Navy non-commissioned officers.

Fluke

A fluke-style anchor

The most common commercial brand is the Danforth, which is sometimes used as a generic name for the class. The fluke style uses a stock at the crown to which two large flat surfaces are attached. The stock is hinged so the flukes can orient toward the bottom (and on some designs may be adjusted for an optimal angle depending on the bottom type). The design is a burying variety, and once well set can develop an amazing amount of resistance. Its light weight and compact flat design make it easy to retrieve and relatively easy to store; some anchor rollers and hawse pipes can accommodate a fluke-style anchor.

The fluke anchor has difficulty penetrating kelp and weed-covered bottoms, as well as rocky and particularly hard sand or clay bottoms. If there is much current or the vessel is moving while dropping the anchor it may "kite" or "skate" over the bottom due to the large fluke area acting as a sail or wing. Once set, the anchor tends to break out and reset when the direction of force changes dramatically, such as with the changing tide, and on some occasions it might not reset but instead drag.

Grapnel

A traditional design, the grapnel style is simple to design and build. It has a benefit in that no matter how it reaches the bottom one or more tines will be aimed to set. The design is a non-burying variety, with one or more tines digging in and the remainder above the seabed. In coral it is often able to set quickly by hooking into the structure, but may be more difficult to retrieve. A grapnel is often quite light, and may have additional uses as a tool to recover gear lost overboard; its weight also makes it relatively easy to bring aboard.

Grapnels rarely have enough fluke area to develop much hold in sand, clay, or mud. It is not unknown for the anchor to foul on its own rode, or to foul the tines with refuse from the bottom, preventing it from digging in. On the other hand, it is quite possible for this anchor to find such a good hook that, without a trip line, it is impossible to retrieve. The shape is generally not very compact, and is difficult to stow, although there are a few collapsing designs available.

CQR (Clyde Quick Release)/Plough

CQR anchor

So named due to its resemblance to a traditional agricultural plough (or more specifically two ploughshares), many manufacturers produce a plough-style design, all based on or direct copies of the original CQR (Secure), a 1933 design by mathematician Geoffrey Ingram Taylor.[2] Owing to a now well established history, ploughs are particularly popular with cruising sailors and other private boaters. They are generally good in all bottoms, but not exceptional in any. The CQR design has a hinged shank, allowing the anchor to turn with direction changes rather than breaking out, and also arranged to force the point of the plough into the bottom if the anchor lands on its side. Another more recent commercial design, the Delta uses an unhinged shank and a plough with specific angles to develop slightly superior performance. Both can be stored in most regular anchor roller systems.

Owing to the use of lead or other dedicated tip-weight, the plough is heavier than average for the amount of resistance developed, and may take a slightly longer pull to set thoroughly. It cannot be stored in a hawse pipe.

The genuine CQR and Delta brands are now owned by Lewmar, although they have both been on-sold several times during their lifetimes.

Bruce/Claw

Bruce anchor

This claw shaped anchor was designed by Peter Bruce from the Isle of Man in the 1970s [3]. Bruce gained its early reputation from the production of large scale commercial anchors for ships and fixed installations such as oil rigs. The Bruce and its copies, known generically as "claws", have become a popular option for smaller boaters. It was intended to address some of the problems of the only general-purpose option then available, the plough. Claw-types set quickly in most seabeds and although not an articulated design, they have the reputation of not breaking out with tide or wind changes, instead slowly turning in the bottom to align with the force.

Claw types have difficulty penetrating weedy bottoms and grass. They offer a fairly low holding power to weight ratio and generally have to be over-sized to compete with other types. On the other hand they perform relatively well with low rode scopes and set fairly reliably. They cannot be used with hawse pipes.

Bruce Anchor Group no longer produces the genuine Bruce, although other companies manufacture copies.

Modern designs

Rocna anchor

In recent years there has been something of a spurt in anchor design. Primarily designed to set very quickly, then generate high holding power, these anchors (mostly proprietary inventions still under patent) are finding homes with users of small to medium sized vessels.

  • The German designed Bügel (or Wasi) has a sharp tip for penetrating weed, and features a roll-bar which allows the correct setting attitude to be achieved without the need for extra weight to be inserted into the tip [4].
  • The Bulwagga is a unique design featuring three flukes instead of the usual two. It has performed well in tests by independent sources such as American boating magazine Practical Sailor [5].
  • The Spade is a French design which has proved successful since 1996. It features a demountable shank and the choice of galvanized steel, stainless steel, or aluminium construction, which means a lighter and more easily stowable anchor [6].
  • The New Zealand designed Rocna has been produced since 2004. It too features a sharp toe like the Bügel for penetrating weed and grass, sets quickly [7], and has a particularly large fluke area. Its roll-bar is also similar to that of the Bügel. The Rocna obtained the highest averaged holding power in SAIL magazine's comparison testing in 2006 [8][9].

Designs of permanent anchors

These are used where the vessel is permanently sited, for example in the case of lightvessels or channel marker buoys. The anchor needs to hold the vessel in all weathers, including the most severe storm, but only occasionally, or never, needs to be lifted, only for example if the vessel is to be towed into port for maintenance. An alternative to using an anchor under these circumstances may be to use a pile driven into the seabed.

Permanent anchors come in a wide range of types and have no standard form. A slab of rock with an iron staple in it to attach a chain to would serve the purpose, as would any dense object of appropriate weight (e.g., an engine block). Modern moorings may be anchored by sand screws which look and act very much like over-sized screws drilled into the seabed, or by barbed metal beams pounded in (or even driven in with explosives) like pilings, or a variety of other non-mass means of getting a grip on the bottom. One method of building a mooring is to use three or more temporary anchors laid out with short lengths of chain attached to a swivel, so no matter which direction the vessel moves one or more anchors will be aligned to resist the force.

Mushroom

Mushroom Anchor on the Lightship Portsmouth in Virginia.

The mushroom anchor is suitable where the seabed is composed of silt or fine sand. It was invented by Robert Stevenson, for use by an 82 ton converted fishing boat, Pharos, which was used as a lightvessel between 1807 and 1810 near to Bell Rock whilst the lighthouse was being constructed. It was equipped with a 1.5 ton example.

It is shaped like an inverted mushroom, the head becoming buried in the silt. A counterweight is often provided at the other end of the shank to lay it down before it becomes buried.

A mushroom anchor will normally sink in the silt to the point where it has displaced its own weight in bottom material, thus greatly increasing its holding power. As it can take time for the mushroom anchor to imbed itself into the seabed and achieve its full holding potential, it is often recommended (that if it is to be lifted when it is checked), that the timing of the check be coordinated to follow the stormy part of the season. These anchors are only suitable for a silt or mud bottom, since they rely upon suction and cohesion of the bottom material, which rocky or coarse sand bottoms lack. The holding power of this anchor is at best about twice its weight unless it becomes buried, when it can be as much as ten times its weight [1]. They are available in sizes from about 10 lb up to several tons.

Deadweight

This is an anchor which relies solely on being a heavy weight. It is usually just a large block of concrete or stone at the end of the chain. Its holding power is defined by its weight underwater (i.e. taking its buoyancy into account) regardless of the type of seabed, although suction can increase this if it becomes buried. Consequently deadweight anchors are used where mushroom anchors are unsuitable, for example in rock, gravel or coarse sand. An advantage of a deadweight anchor over a mushroom is that if it does become dragged, then it continues to provide its original holding force. The disadvantage of using deadweight anchors in conditions where a mushroom anchor could be used is that it needs to be around ten times the weight of the equivalent mushroom anchor.

Screw

Screw anchors can be used to anchor permanent moorings, floating docks, fish farms, etc.

These anchors must be screwed into the seabed with the use of a tool, so require access to the bottom, either at low tide or by use of a diver. Hence they can be difficult to install in deep water without special equipment.

Weight for weight, screw anchors have a higher holding than other permanent designs, and so can be cheap and relatively easily installed, although may not be ideal in extremely soft mud.

Anchoring gear

Naval anchor incorporated into HMAS Canberra (1927) memorial, Canberra, Australia

The elements of anchoring gear include the anchor, the cable (also called a rode), the method of attaching the two together, the method of attaching the cable to the ship, charts, and a method of learning the depth of the water.

Vessels may carry a number of anchors: Bower Anchors (formerly known as Sheet Anchors) are the main anchors used by a vessel and normally carried at the bow of the vessel. A Kedge Anchor is a light anchor used for kedging, or more commonly on yachts for mooring quickly. or in benign conditions. A Killick Anchor is a small, possibly improvised, anchor.[10][11]

Charts are vital to good anchoring. Knowing the location of potential dangers, as well as being useful in estimating the effects of weather and tide in the anchorage, is essential in choosing a good place to drop the hook. One can get by without referring to charts, but they are an important tool and a part of good anchoring gear, and a skilled mariner would not choose to anchor without them.

The depth of water is necessary for determining scope, which is the ratio of length of cable to the depth measured from the highest point (usually the anchor roller or bow chock) to the seabed. For example, if the water is 25 ft (8 m) deep, and the anchor roller is 3 ft (1 m) above the water, the scope is the ratio between the amount of cable let out and 28 ft (9 m). For this reason it is important to have a reliable and accurate method of measuring the depth of water.

A cable or rode is the rope, chain, or combination thereof used to connect the anchor to the vessel. Neither rope nor chain is fundamentally superior as a cable.

Anchoring techniques

Anchor winch on RV Polarstern
Colored plastic inserts on a modern anchor chain show the operator how much chain has been paid out. This knowledge is very important in all anchoring methods

The basic anchoring consists of determining the location, dropping the anchor, laying out the scope, setting the hook, and assessing where the vessel ends up. After using the chart to determine a desirable location, the crew needs to actually see what the situation is like; there may be other boats whose crew thought that would be a good spot, or weather conditions may be different from those expected, or even additional hazards not noted on the chart may make a planned location undesirable.

If the location is good, the location to drop the anchor should be approached from down wind or down current, whichever is stronger. As the chosen spot is approached, the vessel should be stopped or even beginning to drift back. The anchor should be lowered quickly but under control until it is on the bottom. The vessel should continue to drift back, and the cable should be veered out under control so it will be relatively straight.

Once the desired scope is laid out (a minimum of 8:1 for setting the anchor, and 5:1 for holding, though the preferred ratio is 10:1 for both setting, and holding power, although leaving rope three times as long as the depth of the water will usually be plenty), the vessel should be gently forced astern, usually using the auxiliary motor but possibly by backing a sail. A hand on the anchor line may telegraph a series of jerks and jolts, indicating the anchor is dragging, or a smooth tension indicative of digging in. As the anchor begins to dig in and resist backward force, the engine may be throttled up to get a thorough set. If the anchor continues to drag, or sets after having dragged too far, it should be retrieved and moved back to the desired position (or another location chosen.)

With the anchor set in the correct location, everything should be reconsidered. Is the location protected, now and for the forecast weather? Is the bottom a suitable holding ground, and is the anchor the right one for this type of bottom? Is there enough depth, both now and at low tide? Especially at low tide but also at all tide states, is there enough room for the boat to swing? Will another vessel swing into us, or will we swing into another vessel, when the tide or wind changes?

Some other techniques have been developed to reduce swing, or to deal with heavy weather.

Protection

A good anchorage offers protection from the current weather conditions, and will also offer protection from the expected weather. The anchorage should also be suitable for other purposes; for example, proximity to shore is beneficial if the crew plans to land.

Seabed

Charts should indicate the type of bottom, and a sounding lead may be used to collect a sample from the bottom for analysis. Generally speaking, most anchors will hold well in sandy mud, mud and clay, or firm sand. Loose sand and soft mud are not desirable bottoms, especially soft mud which should be avoided if at all possible. Rock, coral, and shale prevent anchors from digging in, although some anchors are designed to hook into such a bottom. Grassy bottoms may be good holding, but only if the anchor can penetrate the foliage.

Depth and tides

If the anchorage is affected by tide, tide ranges, as well as the times of high and low water, should be known. Enough depth is needed so that low tide does not present obstacles to where the vessel might swing. This is also important when determining scope, which should be figured for high tide and not the current tide state.

Swing range

If the anchorage is affected by tide, one should keep in mind that the swing range will be larger at low tide than at high tide. However, no matter where the vessel is anchored, the largest possible swing range should be considered, as well as what obstacles and hazards might be within that range. Other vessels' swing ranges may overlap, presenting a further variable. Boats on permanent moorings, or shorter scope, may not swing as far as expected, or may swing either more rapidly or more slowly (all-chain cables tend to swing more slowly than all-rope or chain-and-rope cables.)

There are techniques of anchoring to limit the swing of a vessel if the anchorage has limited room.

Using an anchor weight, kellet or sentinel

Lowering a concentrated, heavy weight down the anchor line – rope or chain – directly in front of the bow to the seabed, behaves like a heavy chain rode and lowers the angle of pull on the anchor.[12] If the weight is suspended off the seabed it acts as a spring or shock absorber to dampen the sudden actions that are normally transmitted to the anchor and can cause it to dislodge and drag. In light conditions, a kellet will reduce the swing of the vessel considerably. In heavier conditions these effects disappear as the rode becomes straightened and the weight ineffective.

Forked moor

Using two anchors set approximately 45° apart, or wider angles up to 90°, from the bow is a strong mooring for facing into strong winds. To set anchors in this way, first one anchor is set in the normal fashion. Then, taking in on the first cable as the boat is motored into the wind and letting slack while drifting back, a second anchor is set approximately a half-scope away from the first on a line perpendicular to the wind. After this second anchor is set, the scope on the first is taken up until the vessel is lying between the two anchors and the load is taken equally on each cable.

This moor also to some degree limits the range of a vessel's swing to a narrower oval. Care should be taken that other vessels will not swing down on the boat due to the limited swing range.

Bow and stern

Not to be mistaken with the Bahamian moor, below.

In the Bow and Stern technique, an anchor is set off each the bow and the stern, which can severely limit a vessel's swing range and also align it to steady wind, current or wave conditions. One method of accomplishing this moor is to set a bow anchor normally, then drop back to the limit of the bow cable (or to double the desired scope, e.g. 8:1 if the eventual scope should be 4:1, 10:1 if the eventual scope should be 5:1, etc.) to lower a stern anchor. By taking up on the bow cable the stern anchor can be set. After both anchors are set, tension is taken up on both cables to limit the swing or to align the vessel.

Bahamian moor

Similar to the above, a Bahamian moor is used to sharply limit the swing range of a vessel, but allows it to swing to a current. One of the primary characteristics of this technique is the use of a swivel as follows: the first anchor is set normally, and the vessel drops back to the limit of anchor cable. A second anchor is attached to the end of the anchor cable, and is dropped and set. A swivel is attached to the middle of the anchor cable, and the vessel connected to that.

The vessel will now swing in the middle of two anchors, which is acceptable in strong reversing currents but a wind perpendicular to the current may break out the anchors as they are not aligned for this load.

Backing an anchor

Also known as Tandem anchoring, in this technique two anchors are deployed in line with each other, on the same rode. With the foremost anchor reducing the load on the aft-most, this technique can develop great holding power and may be appropriate in "ultimate storm" circumstances. It does not limit swinging range, and might not be suitable in some circumstances. There are complications and the technique requires careful preparation and a level of skill and experience above that required for a single anchor.

Kedging

Statue of Peter the Great leaning on an anchor, in symbol of that Tsar's shipbuilding activity (Voronezh, 1860).

Kedging is a technique for moving or turning a ship by using a relatively light anchor known as a kedge.

In yachts, a kedge anchor is an anchor carried in addition to the main, or bower anchors, and usually stowed aft. Every yacht should carry at least two anchors – the main or bower anchor and a second lighter kedge anchor. It is used occasionally when it is necessary to limit the turning circle as the yacht swings when it is anchored, such as in a very narrow river or a deep pool in an otherwise shallow area.

For ships, a kedge may be dropped while a ship is underway, or carried out in a suitable direction by a tender or ship's boat to enable the ship to be winched off if aground or swung into a particular heading, or even to be held steady against a tidal or other stream.

Historically, it was of particular relevance to sailing warships which used them to out-maneuver opponents when the wind had dropped but might be used by any vessel in confined, shoal water to place it in a more desirable position, provided she had enough manpower.

In Heraldry

A 1914 Russian poster depicting the Triple Entente. Britannia's association with the oceanic British Empire is indicated by her holding a large anchor.

An anchor frequently appears on the flags and coats-of-arms of institutions involved with the sea, both naval and commercial, as well as of port cities and seacoast regions and provinces in various countries.

There also exists in heraldry the "Anchored Cross", or Mariner's Cross, a stylized cross in the shape of an anchor. The symbol can be used to signify 'fresh start' or 'hope'.

The Mariner's Cross is also referred to as St. Clement's Cross in reference to the way this saint was martyred (being tied to an anchor and thrown from a boat into the Black Sea in the year 102).

Anchored crosses are occasionally a feature of coats of arms in which context they are referred to by the heraldic terms anchry or ancre.

Notes

  1. ^ Johnstone, Paul and McGrail, Seán (1989). The sea-craft of prehistory. London: Routledge. ISBN 9780415026352, p.82.
  2. ^ Taylor, G. I. (1974). "The history of an invention". Bulletin of the Institute of Mathematics and its Applications 10: 367–368. doi:10.1017/S0022112086001040.  Cited by Batchelor, G. K. (1986). "Geoffrey Ingram Taylor, 7 March 1886–27 June 1975". Journal of Fluid Mechanics 173: 1–14. doi:10.1017/S0022112086001040. 
  3. ^ Bruce, Peter, U.S. Patent 4,397,256 August 9, 1983
  4. ^ Ginsberg-Klemmt, Erika & Achim, and Poiraud, Alain: "The Complete Anchoring Handbook", Ragged Mountain Press, 2007 (ISBN 0071475087)
  5. ^ Practical Sailor: "Anchor Reset Tests", Belvoir Pubs, January 2001
  6. ^ Poiraud, Alain: "Tout savoir sur le mouillage", Loisirs Nautiques, 2003 (ISBN 2-914423-46-2)
  7. ^ Lowe, Colin: "Gear Test: Rocna Anchor", Boating NZ, July 2006
  8. ^ http://www.hisse-et-oh.com/articles/article.php?article=367
  9. ^ http://www.accademiavelica.it/IT/documentazione/_prova-ancore/index.html
  10. ^ World Wide Words
  11. ^ The "Pusser's Anchor"
  12. ^ Hinz, Earl R.; The Complete Book of Anchoring and Mooring, first ed., 1986, Cornell Maritime Press; ISBN 0-87033-348-8

Bibliography

  • 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

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

ANCHOR (from the Greek iiyKvpa, which Vossius considers is from 5yrcr/, a crook or hook), an instrument of iron or other heavy material used for holding ships or boats in any locality required, and preventing them from drifting by winds, tides, currents or other causes. This is done by the anchor, after it is let go from the ship by means of the cable, fixing itself in the ground and there holding the vessel fast.

The word "anchor" is also used figuratively for anything which gives security, or for any ornament or appendage which takes the same form. Owing to a vessel's safety depending upon the anchor, it is obviously an appliance of great importance, and too much care cannot be expended on its manufacture and proper construction. The most ancient anchors consisted of large stones, baskets full of stones, sacks filled with sand, or logs of wood loaded with lead. Of this kind were the anchors of the ancient Greeks, which, according to Apollonius Rhodius and Stephen of Byzantium, were formed of stone; and Athenaeus states that they were sometimes made of wood. Such anchors held the vessel merely by their weight and by the friction along the bottom. Iron was afterwards introduced for the construction of anchors, and an improvement was made by forming them with teeth or "flukes" to fasten themselves into the bottom; 1 A. C. Lyall, Asiatic Studies (reprinted by Watts and Co., London, 1907), p. 19.

whence the words OSovres and denies are frequently taken for anchors in the Greek and Latin poets. The invention of the teeth is ascribed by Pliny to the Tuscans; but Pausanias gives the credit to Midas, king of Phrygia. Originally there was only one fluke or tooth, whence anchors were called ETepovrouoc; but a second was added, according to Pliny, by Eupalamus, or, according to Strabo, by Anacharsis, the Scythian philosopher. The anchors with two teeth were called &p41 1 30Xoc or (1,01aTo�oe, and from ancient monuments appear to have resembled generally those used in modern days, except that the stock is absent from them all. Every ship had several anchors; the largest, cor d FIG. i. - Rodger's Anchor. FIG. 2. - Improved Martin Anchor.

responding to our sheet anchor, was only used in extreme danger, and was hence peculiarly termed l�pa or sacra, whence the proverb sacram anchoram solvere, as flying to the last refuge.

Until the beginning of the 10th century anchors were of imperfect manufacture, the means of effecting good and efficient welding being absent and the iron poor, whilst the arms, being straight, generally parted at the crown, when weighing from good holding-ground. A clerk in Plymouth Yard, named Pering, in the early part of that century (1813) introduced curved arms; and after 1852 the Admiralty anchor, under the direction of the Board, was supplied to H.M. ships, followed by Lieutenant (afterwards Captain) Rodger's anchor (fig. 1). This marked a great departure from the form of previous anchors. The arms, de, df were formed in one piece, and were pivoted at the crown d on a bolt passing through the forked shank ab. The points or pees e, f, to the palms g were blunt. This anchor had an excellent reputation amongst nautical men of that period, and by the committee on anchors, appointed by the admiralty in 1852, it was placed second only to the anchor of Trotman. Later came the self-canting and close-stowing Martin anchor, which, passing through successive improvements, became the improved Martin anchor (fig. 2) made of forged iron.

A projection in the centre of the arms works in a recess at the hub of the shank; the vacancies outside the shank are filled by blocks bolted through on each side, and are flush with the side plates, which FIG. 3. - Improved Martin-Adelphi keep the flukes in position.

Anchor. The introduction of cast steel in 1894 led to the improved Martin-Adelphi pattern (fig. 3), in which the crown and arms are cast in one, and, with the stock, are made of cast steel, the shank remaining of forged iron. A projection in the crown works in a recess (right, fig. 3), and is secured in its place by a forged steel pin, fitted with a nut and washer, which passes through the crown and the heel of the shank. All the above anchors were provided with a stock (fig. 1, hk), the use of which is to "cant" the anchor. If it falls on the ground, resting on one arm and one stock, when a strain is brought on the cable, the stock cants the anchor, causing the arms to lie at a downward angle to the holding ground; and the pees enter and bury themselves below the surface of the soil.

To stow a stocked anchor on the forecastle, it is hove up close to the forefoot, and by means of a ground chain (secured to a balancing or gravity band on the anchor), which is joined to a catting chain rove through a cat davit, the anchor is hove up FIG. 4. - Anchor Crane.

horizontally and placed on its bed, where it is secured by chains passing over a rod fitted with a lever for "letting go." The cat davit is hinged at its base, and can be laid flat on the deck for right ahead fire or when at sea. Ground and catting chains have been superseded in some ships by a wire pendant and cat hook; the anchor is then hove close up to the hawse-pipe. To avoid cutting away a portion of the forecastle, in the "Cressy," "Terrible" and "Diadem" classes of the British navy, the anchors, secured by chains, are stowed a-cock-bill, outside the ship, with their crowns resting on iron shoes secured to the ship's side and the flukes fore and aft. A difficulty is experienced in stowing the anchors when the ship is pitching or rolling heavily. Fig. 4 illustrates an anchor with cat davit or anchor crane used in the P. and O. Company's steamers ("India" class, 8000 tons); for sea the anchor is stowed on board by the anchor crane.

Stockless anchors have been extensively used in the British mercantile marine and in some foreign navies. In 1903 they were adopted generally for the British navy, after extensive anchor trials, begun in 1885. Their advantages are: - handiness combined with a saving of time and labour; absence of davits, anchor-beds and other gear, with a resulting reduction in weight; and a clear forecastle for "right ahead" gun fire or for working ship. On the other hand a larger hawse-pipe is required, and there appears to be a consensus of opinion that a stockless anchor FIG. 5. - Hall's Improved Stockless Anchor.

FIG. 6. - W. L. Byer's Stockless Anchor.

when "let go" does not hold so quickly as a stocked one, is'more uncertain in its action over uneven ground, and is more liable to "come home" (drag). The stockless anchors principally in use in the British navy are Hall's improved, Byer's, and Wasteneys Smith's. In Hall's improved (fig. 5) the arms and crown of cast steel are in one piece, and the shank of forged steel passes up through an aperture in the crown to which it is secured by two cross bolts. Two trunnions or lugs are forged to the lower end of the shank. In Byer's plan (fig. 6) the flukes and crown consist of a steel-casting secured to a forged shank by a through bolt of mild steel, the axis of which is parallel to the points of the flukes; one end of the bolt has a head, but the other is screwed and fitted with a phosphor bronze nut to allow the bolt to be withdrawn for examination. A palm is cast on each side of the crown to trip the flukes when the anchor is on the ground, and for bringing them snug against the ship's side when weighing. Wasteneys Smith's anchor (fig. 7) is composed of three main parts, the shank and crown which form one forging, and the two flukes or arms which are separate castings. A bolt passes through the crown of the anchor, connecting the flukes to it; to prevent the flukes working off the connecting through bolt, two smaller bolts pass through the flukes at right angles to the through bolt and are recessed half their diameter into it.

Fig. 8 represents the starboard bow of H.M.S. "New Zealand" FIG. 8. - Starboard Bow of H.M.S. "New Zealand." (16,350 tons) with lower and sheet (spare) anchors stowed. To let go a stockless anchor (fig. 9) the cable or capstan holder C is unscrewed, and in practice it is found desirable to knock off the bottle screw-slip A, allowing the weight of the anchor to be taken by the inner slip A' (Blake's stopper). Stern, stream and kedge anchors are usually stowed with special davits. A portable anchor suitable for small yachts is the invention gf Mr Louis Moore; the shank passes through the crown of the anchor like the handle of a pickaxe and the stock over the head of the shank. At the end of the stock are loose pawls. There are no keys or bolts, and the only fastening is for the cable. The anchor takes to pieces readily and stows snugly. In 1890 Colonel Bucknill also invented a portable anchor for small yachts.

Iron buoy-sinkers (fig. 10), as used by the London Trinity House Corporation, weigh from 8 to 40 cwt.; the specified weight is cast on them in large raised figures, and the cast and wrought irons used are of special quality, of which samples are previously submitted to the engineer-in-chief.

The anchors supplied to ships of the British navy are required FIG. 9. - Forecastle of H.M.S. "New Zealand." A. Bottle or screw-slip. B. Deck or navel pipes.

A'. Slip or Blake's stopper. F. Fairleads for wire hawsers.

E. Bitts. H. Hawse-pipes. C. Cable or Capstan-holders. S. Stopper-bolts.

C'. Centre line capstan. R. Rollers.

to withstand a certain tensile strain, expressed in tons, proportionate to their weights in cwts. New anchors are supplied by contractors, but repairs are made in H.M. dockyards, a record of its repairs being stamped on each anchor. In the Anchors and Cables Act 1899 a list is given of authorized testing-establishments, with their distinctive marks and charges, and testinghouses for foreign-owned vessels are enumerated in Table 22 of Lloyd's Sinker. Register of British and Foreign Shipping. Cast-steel anchors, in addition to the statutory tests, are subjected to percussive, hammering and bending tests, and are stamped "annealed steel." (J. W. D.)


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Bible wiki

Up to date as of January 23, 2010

From BibleWiki

From Acts 27:29ff, it would appear that the Roman vessels carried several anchors, which were attached to the stern as well as to the prow. The Roman anchor, like the modern one, had two teeth or flukes. In Heb 6:19 the word is used metaphorically for that which supports or keeps one steadfast in the time of trial or of doubt. It is an emblem of hope.

"If you fear / Put all your trust in God: that anchor holds."

This entry includes text from Easton's Bible Dictionary, 1897.

what mentions this? (please help by turning references to this page into wiki links)


Simple English

File:Admiralty
Old type of anchor
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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.

Contents

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.

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.

Fisherman

The Fisherman has a traditional design that 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.

File:Fluke anchor-1-.gif
A fluke-style anchor

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.

Grapnel

A traditional design, the grapnel style is simple to design and build. It is a simple hook that is good for rock or reefs. It is useless for most other seabeds.

[[File:|thumb|Genuine CQR]]

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.

Bruce / Claw

The genuine Bruce was invented in the 1970's and to try to solve some problems of the plow. Many copies are now made. This type of anchor is now called a "claw-type". Claw anchors 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. Most copies are lower quality than the genuine Bruce.

Modern designs

[[File:|thumb|Genuine Rocna]]

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 to turn the anchor to the correct angle on the seabed
  • The Bulwagga has three flukes instead of two. It has done well in tests by independent organizations [1].
  • The Spade has been well accepted since 1996. It performs well [2].
  • The Rocna has been made since 2004. Like the Bügel', it has a sharp toe and roll-bar for weed and grass. It sets quickly [3], and has a large fluke area. Its roll-bar is similar to the Bügel's, and ensures the correct setting angle with low weight on the tip.[4] The Rocna got the highest averaged holding in SAIL magazine's testing in 2006 [1] [2] [3].

Performance of temporary anchors

[[File:|thumb|275px|left|Chart comparing holding ability of different anchors.]]

Many modern designs are better than the older types. This chart shows tests done by West Marine (an American marine shop) in 2006 [4]. The anchors were tested on three different sandy seabeds, at three different scopes (pull angles).

Six of the seven best anchors on this chart are "modern", but several modern anchors did very badly. This shows that 'newer' is not always better.

Designs of permanent anchors

Permanent anchors are used when a floating thing must be kept in place for a long time. They are used to anchor Lightships, navigation buoys, and moorings. The anchor must hold in all weather, even the worst storm.

Deadweight

A deadweight anchors is a heavy weight. It can be used when the bottom is too hard for other types of anchors. It can be made of a large rock or a concrete block.

Mushroom or Pyramid

File:Portsmouth with mushroom
Mushroom Anchor on the Lightship Portsmouth in Virginia.

Mushroom and pyramid anchors are good where the seabed is soft. This type of anchor needs time to dig into the seabed. It can be smaller and lighter than a deadweight anchor. The mushroom anchor is shaped like a mushroom, and the pyramid anchor is shaped like a pyramid with the apex pointing down.

Modern designs

The sand screw must be screwed into the seabed before it is used. It can be very light.

References

  1. Practical Sailor: "Anchor Reset Tests", Belvoir Pubs, January 2001
  2. Practical Sailor: "Anchor Tests Round 2", Belvoir Pubs, 1999
  3. Lowe, Colin: "Gear Test: Rocna Anchor", Boating NZ, July 2006
  4. Ginsberg-Klemmt, Erika & Achim, and Poiraud, Alain: "The Complete Anchoring Handbook", Ragged Mountain Press, 2007 (ISBN 0-07-147508-7)
  • 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

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