Materials for Mooring rope/chain

Mooring lines and docklines are being produced in various constructions (3-strand, double braided), materials (polyester, nylon, dyneema), diameters etc.

First of all stretch in mooring lines is very important. The mooring line should be able to absorb shocks that are generated by waves or wind. The amount of stretch required is defined by the situation your yacht is moored. Marinas and harbours with good protection require minimal stretch, while mooring places in where you might experience big waves it is important to have great stretch. In this case even extra items may be required such as rubber stretchers.

Stretch is being generated by the right construction and material used in the docklines. 3-strand construction generates very good stretch. The 3-strand construction is the oldest way of making ropes and still very effective for mooring lines! The disadvantage of 3-strand is that it might get a stiff after a while.

The more modern double-braided ropes have 12-strand “woven” core and 32-strand woven cover. This makes the rope very flexible and strong.

The material used is quite important as well. Mooring lines are usually made from manila rope or a synthetic material such as nylon. We now work with materials such as nylon, polyester and dyneema.

Nylon is losing market share in the ropes for yachts. 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. The stretch is good, but the disadvantage is it will shrink and get stiff due to UV radiation.

Mostly used material is nowadays polyester.

Polyester still provides stretch if constructed in the right way. Polyester has a great resistence against abrasion which is a great benefit since mooring lines mainly need to be replaced because of abrasion.

Dyneema actually has even a better abrasion resistance but simple is too slippery to handle. Therefore our dyneema mooring lines are protected with a polyester cover. Dyneema is great for handling; the material is very light and strong. Because the great strength it is possible to work with much smaller diameters whilst still having the same breaking load on the rope.

Since dyneema has virtually no stretch, we recommend using polyester loops as stretchers. The length and diameters of these loops depend on the required stretch, which again is defined by the yacht and mooring properties.

Mooring lines made from materials such as Dyneema 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. 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.