Mooring to a shore fixture::Mooring (watercraft)


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Mooring to a shore fixture

A man at the front of a large boat throws a rope to another man on a nearby pier wearing a blue sailor uniform who is holding a long pole with a hook at the rear to catch it
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 fittings on the shore, such as bollards, rings, or cleats, on the other end.

Mooring requires cooperation between people on the pier and on a vessel. For larger vessels, heavy mooring lines are often passed to the people on the shore by use of smaller, weighted heaving lines. Once the mooring line is attached to the bollard, it is pulled tight. On large ships, this tightening can be accomplished with the help of heavy machinery called mooring winches or capstans.

A sailor tosses a heaving line to pass a mooring line to a handler on shore

For the heaviest cargo ships, more than a dozen mooring lines can be required. Small vessels generally take 4 to 6 mooring lines.

Mooring lines are usually made out of synthetic materials such as nylon. Nylon is easy to work with and lasts for years, but has a property of very great elasticity. This elasticity has its advantages and disadvantages. The main advantage is that during an event, such as a high wind or the close passing of another ship, excess stress can be spread among several lines On the other hand, if a highly stressed nylon line does break, or part, it causes a very dangerous phenomenon called "snapback" which can cause fatal injuries. Snapback is analogous to stretching a rubber band to its breaking point between the hands, and then suffering a stinging blow from the retracting loose ends of the band - in the case of a heavy mooring line this blow carries much more force and can inflict severe injuries or sever limbs. Mooring lines made from materials such as Dyneema and Kevlar have much less elasticity and therefore much safer to use, but the lines do not float on the water, and tend to sink, are costly, so they are used less frequently. Manila rope is preferred.

Some ships use wire rope for one or more of their mooring lines. Wire rope is hard to handle and maintain. There is also a risk of using wire rope on a ship's stern in the vicinity of its propeller.

Combination mooring lines made of both wire rope and synthetic line can also be used. This results in a hawser. This is more elastic and easier to handle than a wire rope, but not as elastic as a pure synthetic line. Special safety precautions must be followed when constructing a combination mooring line.

A typical mooring scheme
A typical mooring scheme
Number Name Purpose
1 Head line Keep forward part of the ship against the dock
2 Forward Breast Line Keep close to pier
3 Forward Spring Prevent from advancing
4 Aft Spring Prevent from moving back
5 Aft Breast line Keep close to pier
6 Stern line Prevent forwards movement

The two-headed mooring bitt 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".<ref></ref> The Oil Companies International Marine Forum recommend the use of such hooks in oil and gas terminals.<ref></ref>

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.

Mediterranean mooring

USS Orion (AS-18) "Med moored" with the stern tied to the pier and two anchors forward, in La Maddalena, Sardinia.

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 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 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.

Types of canal moorings are

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

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

Mooring ring (permanent) affixed between the edge of the canal and the tow path, with (boat operator supplied) rope to the boat.

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.


Canal River Trust<ref></ref> A picture of mooring pin, mooring hook, chain with rings and hammer here <ref></ref>

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Mooring to a shore fixture
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