anchor
An anchor is a device with which a watercraft is moored on the ground so that it is not driven off by wind, currents, waves or other influences. The process is called anchoring . Anchors hold due to their weight and shape .
As a symbol, the anchor stands for loyalty , in Christian symbolism for hope and is often used in coats of arms.
Anchor shapes
On the one hand, there are weight anchors that hold mainly because of their weight. These include above all older anchor types such as the classic stick anchor or, in the simplest case, a heavy stone anchor . On the other hand, there are patent anchors or lightweight anchors which, due to their shape, dig into the ground with one or more flukes when subjected to tensile load via the anchor chain and, despite their lower weight, can have sufficient holding power. Not all anchor types are equally suitable for every ground.
Among the patent anchors include the plow anchor , plow anchor or CQR anchor , the Danforth anchor or anchor plate , the Heuss-anchor , the bracket-anchor , the d'Hone anchor or HKG Clip anchor , the Bruce anchor with no moving parts and many others. A special role is played by the mushroom anchor , with the fire ships are moored or chart symbols for long periods. The four- or six-armed dragline is mainly used in the Mediterranean area by fishermen and as a folding dragger on small pleasure boats. In addition to the shapes that are used for anchoring, there are also (folding) dragons with very narrow flukes that are used to fish lines lying on the bottom. Finally, there are sand anchors, which have a spiral-shaped tip and must be screwed into the sand on sandy seabed or on the shore in order for them to function.
| Names | image | properties |
|---|---|---|
| Stick anchor, admiralty anchor |
|
"Classic" weight anchor, especially for older ships. Consists of a shaft, cross with curved arms as well as the flukes and the ring (shackle) to hold the chain or rope. Holds about 10 times its own weight. Only one of the flukes can dig in. Furthermore, the pole often has to be attached before the anchor can be used; older anchors had a solid crossbar. Stick anchors hold up well on stony, clay or grassy ground. |
| Dragging |
|
The Draggen has four bent flukes, which in principle should hold in every position of the anchor. However, the pulling direction of the chain is often such that the anchor breaks when pulling horizontally, which is not the case with other lightweight anchors. Dragons are therefore rarely used any more. |
| Folding anchors, umbrella anchors, folding hangers |
|
Foldable anchors have four arms that can be folded in like an umbrella. This makes folding anchors easy to stow in boats that do not have an anchor locker, which is why they are common on dinghies and as dinghies. Their holding power is relatively low. |
| Danforth anchor |
|
The Danforth anchor is a light weight anchor which, depending on the subsurface, can hold 3 to 300 times the weight of a stick anchor of the same weight. They do well in silt and clay marl, less well in weed soil. |
| Ploughshare anchor, CQR anchor |
|
Thanks to the plow-shaped head, it digs into soft ground immediately when it pulls. If the ground is hard or grassy, or if the chain is too short, it is difficult to dig in. Holds in place even better than the Danforth anchor. A ploughshare anchor is difficult to stow on board, but it is the standard anchor for boats with a hawse on the forecastle. |
| Bruce anchor |
|
Looks very similar to a ploughshare anchor, but has no movable shaft and can therefore break out in the event of strong swaying (movements of the ship at the anchorage). It is actually only used on boats with a hawse. |
| Bow anchor, Rocna |
|
Another variant of the ploughshare or Bruce anchor; also has a bracket on the back so that the anchor should always turn with the shaft to the ground. |
Anchor harness
The anchor gear consists of an anchor, the anchor shackle (often a swivel shackle) and the anchor chain . The anchor chain creates a stable connection between anchor and ship and at the same time increases the anchor's holding power with its weight: On the one hand, the heavy chain creates friction on the ground, on the other hand, it ensures that the anchor with its shaft lies flat on the ground wherever it is the holding force is greatest. On some smaller ships, the chain is replaced by a hawser , sometimes combined with a few meters of chain directly on the anchor (“chain feed”). Sometimes there are anchor cables with built-in lead weights to compensate for the lower weight of the cable to the chain; alternatively, additional riding weights can be attached to the cable.
Anchors on ships
The anchor commonly used on ships today is the patent anchor . For ships of the navy, special work ships, earlier also lightships , light barrels, etc., there are special anchors suitable for these types of ships.
The anchor is attached to the anchor chain with a shackle , welded or forged connections are unusual today. The chain itself is composed of lengths of 25 meters that are connected to one another by shackles. Each shackle is marked with a light color so that it is easier to count the shackles pulled in when the anchor is lifted; this determines how much anchor chain has already been hauled in. When the anchor is hoisted, the anchor chain runs through the anchor hawk onto the ship's deck, from there through a mechanical chain stopper into the pulling wheel, the chain sprocket of the anchor winch and further into the chain case.
Every large ship has on the back two anchor winches with one anchor and to at least one spare anchor, the anchor Reserve including approval of the classification society must not be carried. As a result, if an anchor is lost, the reserve anchor has to be brought to the ship as quickly as possible, which can be problematic for large ships (anchor weight 20 tons and more).
Length of the chain
The anchor chain or hawser must be inserted (extended) so long that the anchor remains flat on the ground even when the anchor chain is subjected to tensile load, otherwise it will be torn out of the ground and no longer hold. If this is not the case, the ship is moored for a short day . This should only be the case immediately before lifting (breaking out of the ground) and lifting (pulling up), as the holding force of the anchor is then only low.
The length of the anchor chain on seagoing vessels is usually between 10 and 12 Italian shackles . This corresponds to between 275 m and 330 m. Newer cruise ships are equipped with up to 14 shackle chains per anchor, which corresponds to a length of 384 m.
The length of the extended anchor chain is given in shackles in commercial shipping. The instructions before anchoring can be: “5 shackles to the water” or “3 shackles to the capstan ”. It mainly depends on the depth of the water at the anchorage and the nature of the soil (silt, sand, shill, stones, vegetation, etc.). For the first few meters, the chain lies on the seabed and then leads in an arch (bay) up to the ship. The weight of the chain lying on the ground contributes significantly to the holding force. The bay in which the chain hangs from the ship to the bottom is opened when the ship is subjected to a brief force, e.g. B. by pitching movements in rough seas or swell, somewhat stretched and thus acts as a shock absorber against force peaks that could otherwise damage the capstan or break the chain. When the force decreases, the weight of the chain or cable sinks back to the ground and the ship is pulled back to its original location. The greater the expected forces on the ship (from wind pressure, current, swell, ice), the more chain must be put in place. If a lighter hawser is used instead of the chain, it should be selected correspondingly longer.
With little wind and no swell, three to four times the water depth is sufficient as the chain length. In rough seas and strong winds, up to ten times the water depth must be attached to the chain length.
Since an anchored ship sweats around the anchor under the influence of wind and electricity , there is a risk that it will collide with a neighboring ship or with barrels or solid structures in a narrow roadstead if the chain length is too long . If this cannot be shortened without risk, the ship may have to drop anchor and seek out a more suitable anchorage.
In the recreational boating industry, the chain length is usually given in the usual meter. Cruising yachts are equipped with between 50 and 100 meters of chain, small ships sometimes only with a hawser. The size of a yacht allows it to travel closer to the shore than commercial vessels to anchor. Yachts prefer sheltered bays for this. The recommendation remains the same to put 5 to 7 times the water depth on a chain, which can also lead to a large swelling circle. If the bay is too narrow, especially in Scandinavian waters, the ship is (additionally) moored to the shore with lines. Of course, this only works on the cliffs of the archipelago or similar shorelines.
Process of anchoring
Choice of anchorage
In general, it should be clear which anchorage is to be occupied before the anchor maneuver is initiated. The water flow, the wind conditions, the anchorage, the water depth and the location with regard to the shipping routes must be taken into account. It is also important to consider how much mass the ship has and which anchors and their number have to be deployed. If possible, the anchorage should be visible from all sides and should not unduly obstruct road users (anchorage is prohibited in some places). The ship does not lie rigidly at a point that is predetermined by the wind and the current, but it mostly moves almost in a semicircle around the anchor, it swims . With major changes in wind direction or current, the space in which the ship swims can also be a whole circle. This must be taken into account so that the ship remains clear (at a sufficiently large distance) from other anchoring ships, from buoys , solid structures and shoals.
In the vicinity of many ports, the anchorages are determined by the local authorities and shown on the nautical chart. A seagoing ship is often assigned its anchorage by the competent authority or the traffic control system.
Wind and swell
The preferred anchorage is a place with offshore wind (slipstream and in the lee of the coast). It should be noted that the wind can turn, and because of local wind systems ( land and sea wind ) it will do so overnight at many anchorages. It is therefore important to ensure that there is sufficient water depth on land from the chosen anchorage if the ship should drift there. Anchorages in strong onshore winds are avoided, as the ship could run aground if the anchor is not held properly and the propulsion system may malfunction. In addition, considerable swell is to be expected with onshore wind, which can seriously impair the calm.
On seagoing vessels, the bridge must be permanently manned while the anchor is at anchor ( anchor watch ) and the machine must be kept clear for immediate use if the weather is deteriorating. The officer on watch must constantly check the ship's location in order to immediately determine whether the anchor has been driven off or the anchor has broken out. If it is evident that it has been driven away, either more chain has to be put in or the anchor has to be hoisted and the anchorage left. In general, if the ship is at an anchor during the anchor maneuver, the second anchor must always be held so that it can fall. With careful machine maneuvers, the chain and anchor can be relieved somewhat, but this can only be a temporary measure until the anchor is hoisted.
In general, anchors are only anchored in waters with little current in order to be able to guarantee the vehicle a certain grip and not have to fight with wind and current. When the wind is against the current, the sea becomes choppy. At a densely occupied anchorage, in the presence of both wind and currents, one must also take into account that not all ships could swim in unison. Contrary to intuition, motor boats with their high superstructures align themselves with the wind, while sailing ships with their deep lateral plan align with the current.
Water depth
Anchoring is only possible if the anchor chain is long enough for the water depth. The angle between the stretched anchor chain and the anchor base is decisive: the flatter the better. Therefore, the entire chain must be at least five times as long as the water depth. If a line is used instead of a chain, the length of the line must be at least ten times the water depth. One possibility of reducing the chain or line length (with a constant flat angle on the anchor) is to use a riding weight that is attached to the anchor line so that it can be moved (for example with a shackle). Anchoring in tidal waters poses an additional challenge because enough chain has to be put in place so that the chain is still at least five times the depth of the water when the water is falling or the Schwojkreis does not become too big when the water is falling.
On ocean-going ships it occasionally happens that the anchor is anchored when the water is too deep and the anchor cannot be hoisted again later because the power of the capstan is insufficient for the combined weight of anchor and chain. The classification societies stipulate a tensile force that ensures that the anchor and chain can be heaved in at 50 meters. You should therefore avoid anchoring at greater depths.
In the case of greater water depths, the anchor should not be dropped right from the start, otherwise it will pick up too much speed and be damaged on impact on the bottom. From a water depth of around 30 meters, it is safer to first dig out the anchor with the capstan until it is around 10 meters above the ground, and only then disengage the capstan and let the anchor fall the rest of the way.
Anchorage
Depending on the type and nature of the ground, the types of anchors offer different levels of hold:
- Mud (Schl.) Used to be completely unsuitable for anchoring (no liability for stick anchors)
- Schlick (Sk.) Has a very poor primer and was previously unsuitable for longer anchoring (stick anchor sinks too deep)
- Gravel (K.) and stones (St.) are considered difficult to ideal, depending on the grain size of the stones or the gravel and the nature of the anchor
- large stones (g. St.) are problematic because the anchor wedges and can then be applied only with difficulty
- Sound (T.) is a good reason, since it is composed uniformly and certain porosity has
- Sand (Sd.) Is the best anchorage.
The nature of the ground is indicated on the nautical charts. In the area guides, suitable anchorages are described, together with information about the weather conditions - especially wind directions - under which an anchorage is suitable.
To improve the hold of a stick anchor in loose anchorage ground, an anchor shoe was sometimes used in the past, i.e. i. a wooden covering of the plow.
execution
An anchor is not “thrown” but dropped. The command is: anchor drops . When fastened with only one anchor, the vehicle can rotate freely around the anchor ( schwojen ). The choice of an anchorage is based on several criteria, such as water depth, anchorage ground, wind direction and current. If the nature of the subsoil and the water depth are not known, a swivel circle is first driven to check whether the water depths are sufficient at all points within the swivel circle. There are several ways to connect the anchor to the ship: using a chain, a line or a combination of both.
If anchoring is carried out with a patent anchor, the anchor is deployed with slow reverse travel in the direction of the main force to be expected (wind, current). The aim is to initially deploy the anchor gear as straight as possible on the bottom. The anchor is slowly pulled over the ground (“grazing”) and digs into the ground with the fluke lying on the ground . Often, at the end of the anchor maneuver, the chain is pulled vigorously again (by machine power astern) in order to dig the anchor deep and to check the anchor's hold. If the anchor is broken out and pulled over the ground ("streaking"), this can be felt or felt by jerky chain movements.
To get the anchor up again, you can slowly drive towards it to relieve the chain and thus make the anchor winch's work easier. The process of up-bringing is Lichten or hoisting called. The command for the lift is anchor up! . The message Anchor open after the maneuver has been completed means that the anchor has been hoisted (but not necessarily hoisted into the hawse yet). It may then be necessary to report after the (often difficult) pre-heaving of the anchor into the hawse: the anchor is in and has been pre-heaved.
The expression "anchor anchor" is seen in commercial shipping as an unmistakable characteristic of a landlubber - it is not used there. The same applies to the command “heave anchor!”.
Anchor ball and anchor light
An anchored ship must be marked with an anchor ball during the day and with an anchor light at night and when visibility is poor. Both inform other road users that the ship is no longer in motion.
The lights on ships at anchor are prescribed in the collision prevention rules , Article 30:
- Vehicles less than 7 meters in length only have to use an anchor light if they are in a narrow fairway , a fairway, in a roadstead (or in the vicinity thereof) or where other vehicles usually drive.
- Ships that are less than 50 meters long must have a single white all-round light. It should be placed where it is best seen. Sailing ships usually have the anchor light in the mast top.
- Ships longer than 50 meters have a white all-round light in the front part of the ship and another white all-round light near the stern, which is lower than the front one.
- Ships that are longer than 100 meters must also have the deck lighting switched on when anchoring, others are free to do so.
If the ship is aground, two red all-round lights must be placed one above the other or three black balls must be placed one above the other during the day, except for ships less than 12 meters in length.
Anchor buoy
An anchor buoy can be placed above the anchor by connecting a clapper or a small buoy as a floating body to a rope with the anchor. This buoy marks the position of the anchor and gives other ships an indication of where they should preferably not drop anchor. Crossed anchor lines can lead to "anchor salad" when catching up, which is uncomfortable for both ships involved and can lead to the loss of an anchor or the tearing of the other ship. Anchors that could hinder shipping must be marked with yellow pegs with radar reflectors according to the European Inland Waterways Regulations and the German Inland Waterways Regulations . If the anchor buoy is attached to the head of the anchor with a “tripple line”, it can be used to free an anchor that is hooked on the seabed.
variants
Anchoring for mooring
In some harbors where neither dolphins nor mooring lines or buoys are laid out, the anchor is required for mooring. The maneuver known colloquially as Roman Catholic mooring is particularly widespread in the Mediterranean region: the skipper drops the bow anchor a few boat lengths from the quay and then slowly drives back to the jetty, where the boat is also covered with stern lines. Many modern yacht designs have a wide, relatively low stern so that it is easy to go ashore. This mooring variant, which is not easy to navigate in strong winds and requires time for both mooring and casting off, also harbors the risk of “anchor salad” when the harbors are full: when the anchor chains of adjacent ships cross each other, it can be difficult to to raise one's own anchor without pulling out that of a neighbor.
In Scandinavia , the bow is often moored to the jetty or an island. In this case, the (second) anchor is deployed over the stern and the bow is secured to trees or to pegs brought along on land. Berthing forwards is necessary because the water depth below the desired berth often does not drop quickly enough, so that the rudder under the stern would otherwise be damaged.
Anchoring with an additional stern anchor
Stern anchors are additional anchors that are deployed during a storm or to ensure in tight anchorages that the vehicle moves only a little and does not ram other vehicles by moving around its (bow) anchor on its long chain ( schwoit ). In practice, good seamanship demands that the vessel be anchored in such a way that waves can roll against the vessel from the bow.
In the commercial shipping of the stern anchor is especially common where ocean-going towing maneuvers are driven with them by delivering the anchor at a salvage or towing vehicle, ensures there and used the anchor chain as a "rope". This can be seen particularly often in the deep sea oil industry, when an oil tanker has to be brought to its place for loading by oil island suppliers and deep sea tugs during a storm.
Anchoring with additional land festivals
So that the vehicle does not sweat, it can be attached to the shore in addition to the bow anchor with a line on land. The line is attached to the rear of the vehicle and is brought ashore by means of a dinghy or a swimmer and is fastened there, for example on a rock. The disadvantage of this variant, similar to anchoring with an additional stern anchor, is that the vehicle cannot align itself with the wind and / or current and lateral wind, current and swell offers a large area to attack.
Reasons for anchoring
Reasons for anchoring can be weathering (waiting for better weather or better sea), waiting for help (e.g. as an emergency anchor due to inability to maneuver or maneuvering hindrance) or waiting for a berth . In addition, anchoring itself can represent lying at a berth, especially in small harbors or bays. The crew then uses a dinghy to go ashore if necessary.
Anchoring is generally more difficult and risky than mooring, especially because an anchorage is usually less protected than a berth in a harbor (protected by a mole) and anchor can break out in unfavorable conditions. Mooring lines or cables on the jetty do not usually break easily. Anchoring in a lonely bay is a special experience and can also go easy on the budget, because overnight fees are usually charged for berths in the harbor, whereas anchorages can be used free of charge in most places in the world.
See also
- Sea anchors are used to reduce a ship's drift .
- Warpankers are used to move .
- A dragge (also: a draggon ) is a small multi-armed stickless anchor for fishing objects (e.g. lost anchors).
- Roadstead denotes an anchorage in front of the port or within its pier.
- Airships are often moored to anchor masts .
- Large balloons can be slowed down with a tow or sea anchor and anchored to the ground with ropes to heavy masses, structures or pegs.
- Small balloons are given balloon weights that outweigh the buoyancy, Airwalker foil balloons stand up on their feet on the ground.
- Fluke : shovel-shaped part of the anchor
- Muring : fixed chain for mooring ships, especially in the Mediterranean
- Anchor (heraldry)
literature
- Alain Poiraud: Better to anchor . Palstek-Verlag, Hamburg 2004; ISBN 3-931617-20-3 (for yachts and boats)
- Joachim Schult: Anchor properly . Delius Klasing , Bielefeld 1988; ISBN 3-87412-041-4 (for boats and yachts)
- Joachim Schult: Sailors Lexicon . 13th updated edition. Delius Klasing, Bielefeld 2008, ISBN 978-3-7688-1041-8
- Dieter Vierus: Little anchor customer - from anchor stone to patent anchor . Edition Die Barque, Hamburg 1998, ISBN 3-88412-288-6 .
- Müller-Krauss: manual for ship command . Springer-Verlag, Berlin / Göttingen / Heidelberg 1962, Vol. 2, Edition 6; Pp. 321-324.
- Ernst Wagner: Deck work . Hammerich & Lesser, Hamburg 1959, 6th edition; Pp. 182-189.
- Friedrich Woerdemann: Steamship maneuvers . ES Mittler & Sohn, Berlin, Frankfurt / M. 1958, 2nd edition; Pp. 42-64, et al. a.
- Georg-Samuel Benzler: Lexicon of the dyke and hydraulic engineering (...) occurring (...) artificial words and expressions , Kurhannoverischen Oberdeichgräfen in the Duchy of Bremen, 1792, Leipzig [1]
- Seamanship. Yachting manual. 30th edition, Delius Klasing, Bielefeld 2013, ISBN 978-3-7688-3248-9 .
Web links
- Anchoring on long-haul yachts
- Anchoring with an animated representation of the anchor maneuver
- SkipperGuide.de Principle, implementation and variants of anchoring in recreational shipping
Individual evidence
- ↑ see also: Stone anchor from Plymouth .
- ↑ A drag anchor is sometimes also referred to as a grapnel; Dragge and Dregge are identical
- ↑ Segler-Lexikon, keyword stock anchor
- ↑ a b c d e f seamanship. Yachting manual. P. 94 ff.
- ↑ Segler-Lexikon, keyword bow anchor
- ↑ Anchor maneuvers . In: Andreas Siemoneit (Ed.): Nautical Lexicon. Retrieved November 17, 2019.
- ↑ Article "Chain" . Ship lexicon - terms from the world of merchant ships. Retrieved April 3, 2014.
- ^ Seamanship, handbook for yachting. P. 237
- ↑ after Benzler, p. 16
- ↑ to http://www.kollegensegeln.de/Dokumente/Ankern.pdf
- ↑ Johann Christoph Adelung : Grammatical-Critical Dictionary of High German Dialect, 1793: Ankerschuh
- ↑ esys.org: Stock anchor
- ↑ Exception: sand anchor, this must be screwed into the ground by hand and can therefore only be used on land or in shallow waters
- ↑ Inland Waterways Regulations : Section 3.26 Additional designation of vessels, floating bodies and floating systems whose anchors can endanger shipping and their anchors .
- ↑ Inland Shipping Working Group, Inland Transport Committee, Economic Commission for Europe: European Inland Waterways Regulations , Fourth Revised Edition, 2013, § 3.24 and § 3.26.
- ↑ Felix Keßler: What to do if the anchor does not want to go up? In: Yacht . 5th June 2017.
- ↑ Use triple leash . In: Andreas Siemoneit (Ed.): Nautical Lexicon . Retrieved November 17, 2019.
- ^ Seamanship, manual for yachting , 28th edition, pages 191ff