Besides tugs operating in port waters there are seagoing tugs designed for salvage of vessels in remote areas. They are about 150-250 ft (46-76m) tong. powered with 5,000-10,000hp. It’s only natural that they have portable salvage facilities viz, pumps, fire fighting equipment, diving gear, beach gear, patching materials, compressors and cargo handling gear. Salvage boats are manned with trained personnel such as divers, pump engineers, carpenters and riggers. Some salvage companies fly their crews and equipment to the distressed vessels from a central base
Salvage vessels are stationed close to congested traffic routes and areas where accidents occur most frequently.
They effect rescue towing of vessels becoming disabled due lo engine breakdown, fire, loss of propeller 01 steering control and collisions.
Sometimes ships running aground on a submerged reef or on a shoreline due to a navigational emir or failure of aids to navigation such as a buoy, lighthouse or radar need be refloated by tugs on high tide.
In case of severe strandings beach gear consisting of anchors planted hi ■deep water and wins cables connected to purchase tackles on the stranded vessel are used for pulling.
if necessary distressed vessels are made lighter by means of jettisonning or offloading the cargo.
When a vessel sank but the main deck is out of water the hull is patched and water is pumped before refloating. For deep sunken vessels a cofferdam (a waterproof wall) is built around the main deck before patching and pumping is carried out Different techniques may be applied to force water out of the ship to make ft buoyant. The first one is pumping of foam which hardens very quickly forcing the water out. Another technique is the use of expanding plastic particles and the last one is pumping of hollow polystyrene balls into the sunken vessels. One of the most convenient and fastest methods is raising of a sunken vessel by heavy lift floating cranes.
Sunken barges and small vesseJs are refloated by means of pontoons, which are either metal tanks or rubber bags. First, they are flooded alongside the distressed vessel and then the water is forced out by pumping in compressed air thus enabling the sunken vessel to refloat.
Salvage operations are carried out in accordance with the salvage contract with the term «No cure-no pay» which means that the salvor is pafd an award if he saves some property of value, but never in excess of the value of the property saved. The salvage services are estimated taking into account many factors such as value of the property saved and that of salvage boat and equipment, duration and cost of salvage service and others.
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