Features a variety of towing operations
Features a variety of towing operations.A set of facilities that allow a vessel to tow another floating object or itself to be taken in tow is a towing device. A towing device is necessary for each ship, but there is a need for vessels specially designed for towing operations and assisting ships when maneuvering them in port channels. To the elements of the towing device of conventional marine devices, towing ropes and their wiring and securing. In addition to the above-mentioned elements, special towing vessels also provide towing arches and towing winches. There are three ways of towing, differing in the location of the towed and towing vessels . In maritime conditions, the main method of towing is the wake, in which the towed vessel follows the tow on the towing side. The length of the tow rope depends on the conditions under which the book is carried out. When driving in the open water area with probable waves, a long tow line is used, permitting significant relative movements of the vessels. This reduces the resistance of the towed vessel due to the less influence of the strings thrown by the tug of the tug. The disadvantage of wake towing is poor maneuverability, which makes it necessary to move to towing at a short end in the cramped water areas of the PORT channel raids. In difficult conditions, one must abandon the keel towing and resort to towing lag. In this method, the towing vessel is attached to towed ropes, and the mooring fenders are placed between the sides. Such a towing is possible only with a complete absence
Towing methods : a) wake , b)lag , c) push.
there is excitement, because otherwise it is impossible to reliably keep ships and avoid damage to the side when one vessel hits another. In the third mode of towing, the towing vessel is located behind the towed vessel. This arrangement of vessels allows to reduce the negative effect of the jet with my propellers of the towing vessel, to increase the maneuverability of the whole complex. In addition, the resistance of the pusher vessel decreases, since it moves in the passing stream of the towed vessel. Increasing the thrust of the tugboat drives of the tug Tolkaiye is possible in the offshore areas where there is no wave, but it should be noted that the currently used connection methods admit the substance. Vein relative movements of the towed pusher Although the towing is difficult in marine conditions, it stimulated the appearance and development of composite As a consequence of the above, the handling of the tug system is largely responsible for the successful completion of towing operations. e wind and waves can be reduced by changing the speed axlebox Rovkov rate. To reduce the yaw of the towed vessel, the trim is incremented to the stern and the attachment points of the beaded cable are removed as far as possible from the center of gravity of the vessel. These are based on a theoretical study of the question of the stability of a towed vessel on a course. Assume that vessel A is towed by vessel B to position A, the force Fr is equal to the drag at B in towing vessel B and the force R is equal to the water resistance of vessel A. Both these forces are equal in magnitude and reverse in magnitude direction around the axis, At position 11, when the vessel A has turned through the passing center of gravity of the vessel by an angle to it through the forces Fr and the resultant rdromechanical application
Yaw of the towed vessel
forces R provided that there is no wind, as is assumed throughout the rest of the discussion. The force Fr can be decomposed into the components Fr FM, and the curl of R by Re and Ry. The force gives the moment M r, b, which tends to increase the angle of rotation a, ie, the yaw angle. Momeim Mr is a useful moment, it needs to be increased. For this, point A, in which the tug is attached, should be located as far as possible from the center of gravity of the vessel, i.e., from the point G. The moment M is harmful, so it should be reduced. Approximating the point N, n of which the force R is applied, k point G, we decrease the arm b, and hence, it is the moment MR. Increasing the trim on the stern shifts the N point towards the ship’s gravity center. The stable movement of the towed vessel on the course can be achieved by placing a braking device behind its stern, which makes it difficult to yaw. These devices, as a rule, significantly increase the resistance to towing. However, sometimes it can not be avoided. Such a braking device can be used to feed an anchor chain in one or two bows or a cargo net filled with fenders or bays of an old cable to the back of the rope. For towing, each self-propelled or non-self-propelled vessel has a towing device. The main element of the ship’s towing device is a tow rope providing a strong and elastic connection between the vessels. The dimensions of the tow ropes are set by the Rules , depending on the characteristics of the supply. The steel ropes have become the most widespread in the practice of towing. We recommend the use of rugged steel galvanized ropes of TK type having 6×24 144 strands of 7 organic cores
The use of anchor chains in the towing ropes: a) with one tow rope , b) with two tow ropes.
Currently rope-rope ropes are rarely used as tow ropes. The ropes of man-made fibers are increasingly spreading. Because of the large relative displacements in the movement of ships on the agitated sea and their considerable mass, the compliance of the connection provided by the sagging tow rope is of great importance. Complex conditions of sea towage make it necessary to use all the reserves. In the general case, the compliance provided by a flexible link is determined by its deformation by changing the shape of the sagging part. The elasticity of the tow ropes depends on the properties of the material and the length. For ocean tows, for example, the total length of the tow can be up to a kilometer. It includes shock absorbers made of synthetic cables. The chain links allow the concentrated loads to increase the viability of making the communication between ships even more compliant. shows the layout of the tow rope using the anchors and anchors of the towed vessel. To secure the tow rope in the bow, each vessel has a pair of special towing hooks of bits. Kiehs, specially designed to secure the rope when towing another ship, are rarely set on transport ships. Usually their functions are performed by ordinary mooring bollards. In some cases, the towline is attached to the barge by a hatch, mast or superstructure enclosed around the compass. The easiest and most convenient is the fixing of the barge around the hatch coamings. For this it is necessary to have a special tee to which the tow rope and the ends of the barge are attached to the anchor brackets. To select the tow line and the return to the cable
Fixing the Braga for poop towing vessel: 1-tow rope; 2-anchor bracket; 3-the ends of Braga with the bodies; 4-the wire and the bracket; 5-earrings; 6-wooden fenders.
in the region of the ogon connect the bracket with the verbs-hook wire (steel mooring end). On ships that have in the stern, the braces of the barge are shown to be produced in ways. In the bow of the towed judge, if it does not have special tow bollards, the cable is bolted For the passage of the tow rope in the bow and stern eye or tufts, the Cylinders serve the Kipovye structures which are similar to mooring haws. When designing the towing device of the transport pass of the Fat Vessels, it is necessary to make the minimum number of changes to the design of the vessel. The towing of such vessels in the open sea conditions is rather rare, and the forces arising when moving them in the ports of the tugboat. with success can be perceived by the elements of the mooring device. When planning ocean towing of floating objects in each case, a complex approach is required, including the choice of the most favorable time of the year, the towing route with an assessment of the probability of the emergence of dangerous situations. Great attention should be given to the layout of the towing link, the main element, which ensures the reliable performance of towing the open sea. The towing connection includes several bow anchors ion zeni, steel cables, vegetable synthetic cables of adequate strength. Due to their elastic properties, the plant’s synthetic cables serve as shock absorbers for the towing system, the preparation of the object must be carefully considered. For example, in the case of a floating crane, all the superstructures, the spikes of the deck devices cover the necks, steel sheets, welded to each other and to the body in tone. Leave one throat for access to the mall only compartment. The cargo arrow is brought into the marching position, rigging is well fixed. Insufficient attention to the provision of distillation in the open for serious consequences. The show to that sea can bring a ship of hers tea towing the body in this respect from the Pro-de-Janeiro to England. In the crossing of the “Sao Paulo”, two ocean tugs were hauling. The tow rope consisted of a ship and 650 m steel of three bowlines of an anchor lien cable with a diameter of about 130 mm. As a shock absorber, an equally strong cable of 200 m length was used. However, during the severe storm in the North Atlantic, the anchor chain of the battleship could not stand, after which its death was inevitable. In this case, the main cause of the disaster is the wrong choice of the route and the time of the transition. The method of towing the vessels in ice is determined by the ice conditions, but in all cases the length of the tow rope must be less than when working in the open sea. This is due to a sharp deterioration in the steerability of the towed vessel, even with relatively light ice conditions. The distance between vessels is often reduced to 30-40 m. This requires constant attention of the personnel on the towed ship in order to have a back up and to pay off the inertia of the vessel when the towing icebreaker suddenly stops. ice towing an icebreaker the towed vessel is moving closely next to each other