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Wire Rigging Tutorial

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In the world of ships a wire rope or cable is referred to as a wire. There are reasons for this which are no longer important. Most likely it comes from a shortening of wire rope. Early wires were much stronger than natural ropes but they were unfamiliar to sailors at the start of the global industrial revolution of the 1890's.

Early sailors hated metal rigging other than chain for long runs. This was due to unrefined manufacturing techniques that made handling difficult. Additionally, wires under load would break and kill or injure crew members.

The bad reputation is well earned. Wires can easily kill as they snap back like a rubber band that has broken. A broken wire is both heavy and sharp and gives little warning before it breaks.

Anatomy of a Wire

A wire is composed of thin strands that can flex easily. This is what gives wires their flexibility. The individual strands are arranged in bundles and twisted together. Then the bundles are joined and they are also twisted together.

All of the twisting is done in a direction that keeps the elements pressing against each other so they will not lose their twist. This is the same way some fiber rope is manufactured.

Wires are labeled according to the number of strands in a bundle and number of bundles in the finished wire. So a wire labeled 6-19 has six bundles of nineteen strands each.

The number of strands and material gives the wire its characteristics. Low strand counts in the bundles usually mean stiffer wire, high bundle counts in the finished product usually mean greater flexibility and kink resistance.

Wires used in maritime applications are made of stainless steel or steel alloys. Steel wires are much more common than stainless steel and can gain corrosion resistance by galvanizing the strands before twisting.

The Right Wire for the Job

Your classification society or insurer has a lot to say about how you set your rigging. There are certain grades of wire to be used for specific jobs. They are not interchangeable since careful engineering goes into each design.

Lashing - There are many things to secure on a ship and your heavy duty choices come down to chain or wire. Wires are heavily utilized in roll-on-roll-off vessels to secure vehicles. Container vessels also have significant deck lashes using wire.

Towing - Long tow lines made of wire are the most common equipment on tugs. Some high technology lines are Kevlar but there are at least 100 steel wires in use for every Kevlar line.

Towing wires are carefully maintained and inspected since the loads are very high and breakage is often deadly for exposed winch operators. Luckily breakage is rare with proper care since modern wires are much more resilient than their early counterparts.

Lifting - Lifting wires are heavily regulated and often logged for the life of the wire. Overhead lifting has dangers from falling objects but also from wires whipping as they snap.

Wire Care

Above all wires must be kept clean. Proper storage is also important so the wire does not get out of shape or kinked.

Fine sand and other particles can work their way into the twists and cause abrasion and strand failure. Wires need to be carefully inspected for broken strands since one missing strand will allow the neighboring strands to move and flex beyond the design specifications causing increased wear.

Any kinks or other types of damage may make replacement necessary.

Best practices must also be followed when using thimbles to form eyes for shackles or hooks.

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