Task 1: Synthetic Fibre Ropes

1.Polypropylene (Characteristics,Advantages,Disadvantages) Is the most popular of the man-made fibres at sea. Is reasonablyeconomical very cheap. Has same strength even if its wet or dry. Is used for mooring ropes. Is permanently damaged and weakened from exposure to heat and UV radiation such as that present in sunlight. Affects acids,alkalis and oils. A by-product from polypropylene called fibrefilm, is a very cheap version of the fibre and it is very common used on board ships. Is lightweight and easier to handle in thicker diameters. Is not the strongest rope around; its not recommended for safety ropes which might be exposed to very high stresses. Is stiff and slippery and is notorious for coming undone because it slips out of knots and cleats. It is highly flexibile and has minimum stretch. It has the lowest melting temperature from all synthetic fibre ropes ( 150 F).

Fig.1: Polypropylene Ropes

2.Polythene (Characteristics,Advantages,Disadvantages) It absorbs only 0.01 % water. Its used on mooring tails and mooring ropes. It doesnt float and in cold climates they tend to stiffen up and become difficult to handle. They are not that economic in comparation with polypropylene. Due to its materials, it has a good resistance to UV radiation and sunlight. Is very close to nylon in strength when a steady force is applied. It stretches very little and cant absorb shock loard as well. It is also as equally resistant to moisture and chemicals as nylon, but is superior in resistance to abrasion and sunlight.

Fig.2: Polythene Ropes

3.Nylone (Characteristics,Advantages,Disadvantages) Is the strongest of all the man-made fibre ropes. It has a very excellent elasticity and a good schock absorber; this makes it a good choice for live loards, including towing and anchoring. It does not float. It is transparent to infrared light. It has a good resistance against UV radiations, oil and organic solvents. It does not burn when it break down in fire it forms hazardous smoke, or ash. It is sensitive to high temperatures and will degrade releasing toxic materials including cyanide. Because it absorbs water it is liable to stain; this is not necessarily harmful but can be unsightly. It resists rot and mildew but can stain particularly in water soluble stains. It looses strength when its wet. If it is repeatedly cycled at high percentage of its breaking strength, it generates a large amount of internat heat,which degrades the performance of it and can cause failure at high loads, such as anchor rodes during a hurricane.

Fig.3: Nylon RopesTask 2

In the fig4, we deal with a Direct Pipeline System. Direct Pipeline is the simplest type of pipeline system that uses a few valves than the other types. Its main role is that it takes oil directly from the tank to the pump and it reduces friction. This has an affect of increasing the rate of discharge. It is easy to operate and less crew is required. The role of the few valves is that it takes less time to set it the valve system before commencing a cargo operation. Also, it is a very inflexible system, which makes it very difficult to plan for a multiportdischarge. Block stowage has to be used which makes it difficult to control the trim operation. Washing in the direct pipeline system is pretty difficult because there is no circular system and the washings must be flushed into the tanks. In my point of view, the Direct Pipeline System is the most efficient system, when we speak about discharging and loading the tanks with the cargo. I think that because it takes less time and it doesnt cost to much to maintain it.

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