A mooring is any permanent structure to which a seaborne vessel (such as a boat, ship, or amphibious aircraft) may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring.[1]
These moorings are used instead of temporary anchors because they have considerably more holding power. They cause lesser damage to the marine environment, and are convenient. Where there is a row of moorings they are termed a tier.[2] They are also occasionally used to hold floating docks in place. There are several kinds of moorings:
Swing moorings
Swing moorings also known as simple or single-point moorings, are the simplest and most common kind of mooring. A swing mooring consists of a single anchor at the bottom of a waterway with a rode (a rope, cable, or chain) running to a float on the surface. The float allows a vessel to find the rode and connect to the anchor. These anchors are known as swing moorings because a vessel attached to this kind of mooring swings in a circle when the direction of wind or tide changes.
For a small boat (e.g. 22' / 6.7 m sailing yacht), this might consist of a heavy weight on the seabed, a 12mm or 14mm rising chain attached to the "anchor", and a bridle made from 20mm nylon rope, steel cable, or a 16mm combination steel wire material. The heavy weight (anchor) should be a dense material. Old rail wagon wheels are used in some places (e.g. Clontarf, Dublin, Ireland) for this purpose. In some harbours (e.g. Dun Laoghaire, Ireland), very heavy chain (e.g. old ship anchor chain) may be placed in a grid pattern on the sea bed to ensure orderly positioning of moorings. Ropes (particularly for marker buoys and messenger lines) should be "non floating" to reduce likelihood of a boat's propeller being fouled by one.
Pile moorings
Pile moorings are poles driven into the bottom of the waterway with their tops above the water. Vessels then tie mooring lines to two or four piles to fix their position between those piles. Pile moorings are common in New Zealand but rare elsewhere.
While many mooring buoys are privately owned, some are available for public use. For example, on the Great Barrier Reef off the Australian coast, a vast number of public moorings are set out in popular areas where boats can moor. This is to avoid the massive damage that would be caused by many vessels anchoring.
Twenty foot diameter sheet pile cell mooring structure and five steel pipe pile tripods
Pile cluster and another sheet pile cell mooring structure
There are four basic types of permanent anchors used in moorings:[3]
Dor-Mor pyramid-shaped anchors used in mooring
Dead weights are the simplest type of anchor. They are generally made as a large concrete block with a rode attached which resists movement with sheer weight; and, to a small degree, by settling into the substrate. In New Zealand old railway wheels are sometimes used. The advantages are that they are simple and cheap. A dead weight mooring that drags in a storm still holds well in its new position. Such moorings are better suited to rocky bottoms where other mooring systems do not hold well. The disadvantages are that they are heavy, bulky, and awkward.
Mushroom anchors are the most common anchors and work best for softer seabeds such as mud, sand, or silt. They are shaped like an upside-down mushroom which can be easily buried in mud or silt. The advantage is that it has up to ten times the holding-power-to-weight ratio compared to a dead weight mooring; disadvantages include high cost, limited success on rocky or pebbly substrates, and the long time it takes to reach full holding capacity.[4]
Pyramid anchors are pyramid-shaped anchors, also known as Dor-Mor anchors. They work in the upside-down position with the apex pointing down at the bottom such that when they are deployed, the weight of wider base pushes the pyramid down digging into the floor. Lateral pulls cause the side edges or corners of the pyramids to dig deeper under the floor, making them more stable.[5][6]
Screw-in moorings are a modern method. The anchor in a screw-in mooring is a shaft with wide blades spiraling around it so that it can be screwed into the substrate. The advantages include high holding-power-to-weight ratio and small size (and thus relative cheapness). The disadvantage is that a diver is usually needed to install, inspect, and maintain these moorings.
Multiple anchor mooring systems use two or more (often three) light weight temporary-style anchors set in an equilateral arrangement and all chained to a common center from which a conventional rode extends to a mooring buoy. The advantages are minimized mass, ease of deployment, high holding-power-to-weight ratio, and availability of temporary-style anchors.
Mooring to a shore fixture
Crew of Hong Kong's Star Ferry using a billhook to catch a hemp mooring rope.
A vessel can be made fast to any variety of shore fixtures from trees and rocks to specially constructed areas such as piers and quays. The word pier is used in the following explanation in a generic sense.
Mooring is often accomplished using thick ropes called mooring lines or hawsers. The lines are fixed to deck fittings on the vessel at one end and to fittings such as bollards, rings, and cleats on the other end.
Mooring requires cooperation between people on a pier and on a vessel. Heavy mooring lines are often passed from larger vessels to people on a mooring by smaller, weighted heaving lines. Once a mooring line is attached to a bollard, it is pulled tight. Large ships generally tighten their mooring lines using heavy machinery called mooring winches or capstans.
A sailor tosses a heaving line to pass a mooring line to a handler on shore.
The heaviest cargo ships may require more than a dozen mooring lines. Small vessels can generally be moored by four to six mooring lines.
Mooring lines are usually made from manila rope or a synthetic material such as nylon. Nylon is easy to work with and lasts for years, but it is highly elastic. This elasticity has advantages and disadvantages. The main advantage is that during an event, such as a high wind or the close passing of another ship, stress can be spread across several lines. However, should a highly stressed nylon line break, it may part catastrophically, causing snapback, which can fatally injure bystanders. The effect of snapback is analogous to stretching a rubber band to its breaking point between your hands and then suffering a stinging blow from its suddenly flexing broken ends. Such a blow from a heavy mooring line carries much more force and can inflict severe injuries or even sever limbs. Mooring lines made from materials such as Dyneema and Kevlar have much less elasticity and are therefore much safer to use. However, such lines do not float on water and they do tend to sink. In addition, they are relatively more expensive than other sorts of line.
Some ships use wire rope for one or more of their mooring lines. Wire rope is hard to handle and maintain. There is also risk associated with using wire rope on a ship's stern in the vicinity of its propeller.
Mooring lines and hawsers may also be made by combining wire rope and synthetic line.[clarification needed] Such lines are more elastic and easier to handle than wire rope, but they are not as elastic as pure synthetic line. Special safety precautions must be followed when constructing a combination mooring line.
The two-headed mooring bitts is a fitting often-used in mooring. The rope is hauled over the bitt, pulling the vessel toward the bitt. In the second step, the rope is tied to the bitt, as shown. This tie can be put and released very quickly. In quiet conditions, such as on a lake, one person can moor a 260-tonne ship in just a few minutes.
Quick release mooring hooks provide an alternative method of securing the rope to the quay: such a system "greatly reduces the need for port staff to handle heavy mooring ropes … means staff have to spend less time on exposed areas of the dock, and [reduces] the risk of back injuries from heavy lifting".[8] The Oil Companies International Marine Forum recommend the use of such hooks in oil and gas terminals.[9]
The basic rode system is a line, cable, or chain several times longer than the depth of the water running from the anchor to the mooring buoy, the longer the rode is the shallower the angle of force on the anchor (it has more scope). A shallower scope means more of the force is pulling horizontally so that ploughing into the substrate adds holding power but also increases the swinging circle of each mooring, so lowering the density of any given mooring field. By adding weight to the bottom of the rode, such as the use of a length of heavy chain, the angle of force can be dropped further. Unfortunately, this scrapes up the substrate in a circular area around the anchor. A buoy can be added along the lower portion of rode to hold it off the bottom and avoid this issue.
Other types
Non-line mooring ("hands-free") is used where pier time is highly valuable, and includes suction cups[10][11][12] or magnets.[13][14] It can also be used between ships.[15]
Mediterranean mooring, also known as "med mooring" or "Tahitian mooring", is a technique for mooring a vessel to pier. In a Mediterranean mooring the vessel sets a temporary anchor off the pier and then approaches the pier at a perpendicular angle. The vessel then runs two lines to the pier. Alternatively, simple moorings may be placed off the pier and vessels may tie to these instead of setting a temporary anchor. The advantage of Mediterranean mooring is that many more vessels can be connected to a fixed length of pier as they occupy only their width of pier rather than their length. The disadvantages of Mediterranean mooring are that it is more likely to result in collisions and that it is not practical in deep water or in regions with large tides.
Travelling/running mooring
A mooring used to secure a small boat (capable of being beached) at sea so that it is accessible at all tides. Making a Travelling Mooring involves (1) the sinking of a heavy weight to which a block (pulley wheel) is attached at a place where the sea is sufficiently deep at low tide, (2) fitting a block / pulley wheel to a rock or secure point above the high tide mark, and (3) running a heavy rope with marker buoy between these blocks.
Mooring involves (a) beaching the boat, (b) drawing in the mooring point on the line (where the marker buoy is located), (c) attaching to the mooring line to the boat, and (d) then pulling the boat out and away from the beach so that it can be accessed at all tides.
Canal mooring
A wooden mooring bollard
A mooring used to secure a narrowboat (capable of traversing narrow UK canals and narrow locks) overnight, during off boat excursions or prolonged queuing for canal lock access. Water height with minimal exceptions, remain constant (not-tidal); there is water height variance in close proximity to locks.[16]
Types of canal moorings:
Mooring pin (boat operator supplied) driven into the ground between the edge of the canal and the towpath with a mooring-line rope to the boat.[17]
Mooring hook (boat operator supplied) placed on the (permanent) canal-side rail with either (boat operator supplied) rope or chain-and-rope to the boat.[17]
Mooring ring (permanent) affixed between the edge of the canal and the tow path, with (boat operator supplied) rope to the boat.[17]
Mooring bollard (permanent) affixed canal-side on lock-approaches for the short-term mooring of advancing boats and lock-side to assist in ascent and descent.[17]
An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα.
Seamanship is the art, knowledge and competence of operating a ship, boat or other craft on water. The Oxford Dictionary states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea."
A marina is a dock or basin with moorings and supplies for yachts and small boats. A marina differs from a port in that a marina does not handle large passenger ships or cargo from freighters.
A longboat is a type of ship's boat that was in use from circa 1500 or before. Though the Royal Navy replaced longboats with launches from 1780, examples can be found in merchant ships after that date. The longboat was usually the largest boat carried. In the early period of use, a ship's longboat was often so large that it could not be carried on board, and was instead towed. For instance, a survey of 1618 of Royal Navy ship's boats listed a 52 ft 4 in longboat used by the First Rate Prince, a ship whose length of keel was 115 ft. This could lead to the longboat being lost in adverse weather. By the middle of the 17th century it became increasingly more common to carry the longboat on board, though not universally. In 1697 some British ships in chase of a French squadron cut adrift the longboats they were towing in an attempt to increase their speed and engage with the enemy.
Boat building is the design and construction of boats and their systems. This includes at a minimum a hull, with propulsion, mechanical, navigation, safety and other systems as a craft requires.
A diving shot line, shot line, or diving shot, a type of downline or descending line, is an item of diving equipment consisting of a ballast weight, a line and a buoy. The weight is dropped on the dive site. The line connects the weight and the buoy and is used by divers to as a visual and tactile reference to move between the surface and the dive site more safely and more easily, and as a controlled position for in-water staged decompression stops. It may also be used to physically control rate of descent and ascent, particularly by surface-supplied divers.
A sea anchor is a device that is streamed from a boat in heavy weather. Its purpose is to stabilize the vessel and to limit progress through the water. Rather than tethering the boat to the seabed with a conventional anchor, a sea anchor provides hydrodynamic drag, thereby acting as a brake. Normally attached to a vessel's bows, a sea anchor can prevent the vessel from turning broadside to the waves and being overwhelmed by them.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
In sailing, a sheet is a line used to control the movable corner(s) (clews) of a sail.
A drogue is a device trailed behind a boat on a long line attached to the stern. A drogue is used to slow the boat down in a storm and to prevent the hull from becoming side-on to the waves. A boat that has deployed a drogue should not overspeed down the slope of a wave and crash into the next one, nor will the vessel broach. By slowing the vessel, the drogue makes the vessel easier to control in heavy weather and will help to prevent pitchpoling.
Seine fishing is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.
Braye Harbour is the main harbour on the north side of the island of Alderney, in the Channel Islands, a dependency of the British Crown. A 3,000 feet (910 m) breakwater was built by the Admiralty to protect the Navy in the 19th century shelters Braye Harbour. The harbour faces out onto the Swinge, which is part of the English Channel, and it is at Braye that most of the island's freight comes in. Braye is more or less a suburb of St Anne, the island capital; the centre of St Anne lies approximately 1 mile from the harbour.
A windlass is a machine used on ships that is used to let-out and heave-up equipment such as a ship's anchor or a fishing trawl. On some ships, it may be located in a specific room called the windlass room.
To worm, parcel and serve a line is to apply a multi-layered protection against chafe and deterioration to standing rigging. It is a technique not usually used on modern small boats, but is found extensively on traditionally-rigged sailing ships. Worming, parcelling and serving —referred to collectively as "service"— is traditionally applied only to traditional twisted rope, either natural fiber or steel wire-rope, not the braided line almost exclusively used on modern vessels, but some traditional vessels now use modern high modulus braided lines in place of wire rope and serve the line to maintain the traditional appearance. It can be applied to the entire length of a line, such as a shroud, or selectively, to specific parts of a line, such as over the spliced ends of a stay, where the chafe on the middle section of the stay precludes complete protection.
A mooring in oceanography is a collection of devices connected to a wire and anchored on the sea floor. It is the Eulerian way of measuring ocean currents, since a mooring is stationary at a fixed location. In contrast to that, the Lagrangian way measures the motion of an oceanographic drifter, the Lagrangian drifter.
A Single buoy mooring (SrM) is a loading buoy anchored offshore, that serves as a mooring point and interconnect for tankers loading or offloading gas or liquid products. SPMs are the link between geostatic subsea manifold connections and weathervaning tankers. They are capable of handling any tonnage ship, even very large crude carriers (VLCC) where no alternative facility is available.
A current meter is an oceanographic device for flow measurement by mechanical, tilt, acoustical or electrical means.
In underwater diving, a downline is a piece of substantial cordage running from a point at the surface to the underwater workplace, and kept under some tension. It can be used as a guideline for divers descending or ascending, for depth control in blue-water diving, and as a guide for transfer of tools and equipment between surface and diver by sliding them along the downline at the end of a messenger line. A shotline is a special case of downline which uses a heavy weight at the bottom and a float at the top. A jackstay is a more lateral equivalent, that commonly follows a surface, and will not usually allow materials transfer without a messenger line from the destination end.
A jackstay is a cable or bar between two points to support and guide a load between those points, or as an anchor to attach something to be constrained along that line. The term is mostly used in a marine context and originated on sailing ships. Note the use of "stay" implies load bearing working rigging. In diving it is also a line to guide the movements of a diver between the endpoints.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
References
↑ Maloney, Elbert S.; Charles Frederic Chapman (1996). Chapman Piloting, Seamanship & Small Boat Handling (62ed.). Hearst Marine Books. ISBN978-0-688-14892-8.
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