Ropes have a variety of usages on board a ship. Ropes were the most highly seen equipment on a ship’s deck in the olden days. Though technology has reduced their usage to a certain extent, ropes still have many important applications in a ship’s operation.
Different types of ropes are used for different applications on a ship. The thickness, strength and length of the rope depend on the rope’s usage. The material from which ropes are made can be both, man-made and natural. It is on the basis of the characteristics of these materials that the selection of rope type is done for a particular use.
If we go back to our ancestral age, ropes were widely used in almost all the day to day activities. All these ropes were built from materials found in the natural environment. In those days, fishermen and boaters used ropes made from natural fibers such as helm or sisal. However, presently these materials have been substituted by the modern synthetic materials, which are stronger and durable.
However, choosing a material for a particular rope is a difficult task because each and every material has its own negative and positive points. Knowing the characteristics of a material helps a sailor or boater to choose a rope for specific uses and operations. The different characteristics of materials that one needs to keep in mind are cost, strength, elasticity, durability and resistance to chemicals, water and sunlight.
Let’s take a look at the most common materials of ropes.
Rope materials can be classified into two main categories:
Though obsolete on commercial vessels, natural materials are still used for making ropes by many fishermen and small vessel owners. In the olden days, ropes were made from materials such as sisal, hemp and cotton. The main disadvantage of natural fibers is that they are shorter in length, which makes them weaker and more brittle. This also makes the rope surface harder and difficult to handle. Also, for higher strengths the diameter of the rope needs to be larger. Moreover, all the natural materials have a tendency to absorb more of moisture, which makes them freeze. These materials also have a tendency to decay and degrade from insects, rot and fungus infestation.
Synthetic ropes have substituted almost all the natural material ropes. These ropes are used in a variety of applications because of the long length of their fibers, which increases the strength and durability of the materials. The different types of synthetic materials are:
This is one of the most widely used fibers because of its strength and high resistance to load and degradation. Having very low elasticity, polyester does not stretch and is thus less affected by wear and tear. It also has a high resistance towards chemicals, acids, water and sunlight. The ropes made of polyester do not float and are generally used for mooring applications.
This is the only manmade fiber that is affected by sunlight and thus needs various additives during making. Polypropylene can be made from a single filament fiber or a multi filament-fiber. A polypropylene rope is not used where more of friction is there. Resistant to most of the chemicals, the ropes made from these materials are lighter and float on water.
Generally used for making light weight ropes, this plastic easily wears and tears. The rope made out of this material is a bit difficult to tie in knot. Due to the light weight of the material, the rope made out of it floats on water.
Also known as nylon, it is one of the strongest manmade materials for ropes. It is elastic, durable and is not affected by chemicals or water. Though the material loses strength when wet, it has a high ability to absorb loads, tension and shocks. Ropes made from nylon float on water.