8 Ropes and Wires Regardless of the type of ship you are serving on, ropes and wires are part of your daily existence and, if outside the engine room, they are your responsibility Using the correct cordage in the proper way and the inspection of this is essential Too many lives at sea are lost by the abuse of wires and ropes and the failure to inspect and replace defective items Most heavy work ropes at sea are Manila, sisal, nylon or polypropylene, and the chart below provides a comparison "Ratings: Best -1, Poorest - 8.1 Manila Rope The main problem with Manila rope is that it has to be stored dry, which causes difficulties if it is used as mooring rope and has to be stowed below in a wet condition If this occurs the line should 50 be flaked down, if possible, to give it the best chance of drying out Other problems are that it is heavy, particularly when wet, and does not float, requiring more manpower in handling Deterioration of the rope is indicated by a discolouration from yellowish white to grey, although to distinguish this from surface grime the inner part of the rope has to be inspected A further indication of deterioration is bristling ends of broken yarn, and rope that is overstrained will show a decrease in diameter Natural rope when overstrained will give out cracking noises and wet rope can show a steamlike vapour All of these signs indicate a line that is in danger of breaking In normal usage natural fibre rope deteriorates by around 30% in two years 8.2 Sisal Rope This is again a natural fibre rope, considerably cheaper than Manila and therefore niton used instead of it It has about 80% of the strength of Manila and lasts about the same time, although it is easily damaged by continuous exposure to weather 8.3 Nylon Rope Of the synthetic ropes, nylon is the best It is more expensive than Manila but lasts longer and, on an equal diameter, is times stronger, It is impervious to weather and can be stowed away when wet as it does not absorb water II is particularly good for mooring lines and any other use where limited shock is required as it stretches up to 30% of its length under normal working loads without any degradation of the line Similar to Manila rope, nylon rope when under strain emits cracking noises and can also show the same steam-like vapour when wet Synthetic rope should always have more turns put on bits than natural fibre rope as the friction ratio Is less While all rope under strain should be kept well clear of, nylon rope in particular must be treated very carefully because of the severe backlash on breaking, with the rope possibly stretched to up to 50% of its length at this point 8.4 Polypropylene Rope This is cheaper than nylon rope, does not stretch as well and so produces more shock It is not as strong but it does have some advantages in that it floats and is lighter than a nylon rope of equal diameter, so is easier to handle It is more susceptible to damage from sunlight though and should be kept covered when stowed outside 8.5 Wire Ropes Wire rope consists of a number of strands laid helically around a supporting core Individual strands are composed of a number of wires laid helically around a centre (core) of wire or fibre The lay of a wire rope is defined by the direction in which the strands are laid into the rope, and by the direction in which the wires are laid into the strands 8.6 Wire Rope Cores At the centre of every wire rope is a core, usually made from either wire or fibre The core acts as foundation for the strands, keeps the rope round and provides clearance between the rope strands for unrestricted movement Ropes with fibre cores have greater elasticity, but metallic cores afford greater strength and resistance to crushing The following different kinds of wire rope cores are available: Independent Wire Rope Core (IWRC), wire strand, Manila fibre, sisal fibre or polypropylene Under normal operating conditions, a fibre core provides fully adequate support for the strands and acts as a reservoir for the lubricant Wire cores are usually composed of a separate x wire rope, termed Independent Wire Rope Core (IWRC) In any case where heavy loads or over-winding on a drum will cause excessive pressure of strands against the core, the IWRC is a necessity 52 8.8 Handling Upon receiving a shipment of wire rope, close attention to the packaging is the first important measure in proper and appropriate care If, for example, the reel has broken or split flanges or loose inner sleeves, it is a fair assumption that there could be damage to the rope as well Always check for distortions in the outer wraps of the reel or any conditions resulting from forklift abuse 8.9 Care and Inspection Wire rope is subject to the same wear and tear of all metals at sea If the diameter of the wire is decreased it is an indication that the wire has been under strain for a prolonged time A good indication of deterioration of wire rope is broken wire strands standing proud of the wire These are commonly called fishhooks as they can rip open an unwary hand or, if wearing gloves, can catch on the glove and drag the wearer's hand into a block or drum To prevent corrosion and rust the wire must be lubricated regularly Some wires are galvanised to prevent rusting, but in this process the strength of the wire deteriorates by up to 10% 53