Improving the safety of towing by transport vessels

During the operation of the fleet, there is a need for emergency towing operations by transport vessels. For these purposes, as a rule, standard steel tow ropes are used, the length of which is set by the Rules of the USSR Register in the range of 190-300 m. Ropes of this length have low damping properties, so their use is limited by favorable weather conditions. So, for example, with a rope length of 300 m with a safety factor that meets the requirements of good maritime practice, the permissible wave height is 0.7—1.2 m, which corresponds to a wave of 3 points. Consequently, the towing capabilities of transport vessels are significantly limited.

In order to expand these capabilities during emergency towing on a wave, good maritime practice recommends that a section of the anchor chain of an emergency object (sometimes together with an anchor) be included in the tow line, which is not always feasible in difficult weather conditions and an emergency situation.

The rules of the USSR Register allow the possibility of using synthetic ropes as tow ropes and regulate the choice of their strength characteristics. However, the Rules do not put forward special requirements for the minimum allowable length of elastic inserts, as is done for steel tow ropes. The length of the elastic insert determines its fatigue strength, sets the minimum allowable wave height when towing on a wave and is therefore a very important characteristic of the tow line.

To improve the safety of emergency towing by transport vessels, it is recommended to introduce elastic inserts made of synthetic ropes into the regular towing supply of these vessels. At the same time, it is necessary to develop recommendations for choosing the minimum allowable length of these inserts.

As practice shows, the efficiency and safety of towing unmanageable objects when using synthetic ropes as braking ropes also increase. It is known that uncontrolled objects when towed on tow ropes under the action of hydrodynamic forces prowl. In the process of yawing, the resistance of the towed object increases, the speed and safety of towing decrease. The use of various kinds of travois to eliminate yawing is ineffective, especially when towing large floating objects. To avoid yawing, a stern tow truck is used, which follows the stern of the towed object and creates traction back by the operation of its own screws and the resistance of the hull.

With this method, it is most effective to use two nylon ropes wound from the right and left sides of the aft extremity of the towed object to the brake tow truck. As a result, with the optimal choice of the brake stop and the exclusion of yaw resistance of an uncontrolled object, it is possible to achieve an increase in the speed of the caravan.

The expedition detachment of the Baltic Shipping Company ASPTR carried out two towing of semi-submersible platforms with a displacement of 2,034 tons from the port of Myantyuluotto (Gulf of Bothnia) to Leningrad. The main tow in both cases was the icebreaker "Ivan Kruzenshtern" with a capacity of 3970 kW (5400 hp), working at full speed. The icebreaker "Yuri Lisyansky" was used as auxiliary vessels in the first towing, and the rescuer "Hermes" was used in the second.

The braking vessels in both cases became nose forward, with the icebreaker "Yuri Lisyansky" working backward at a low speed, and the rescuer "Hermes" working backward at an average speed. As a result, the average towing speed, despite the 6-7-point wind, was 6 knots, which exceeded the planned speed by 1 knot. The saving of the running time on the 468-mile journey was in each case one day. The economic effect only due to the reduction of running time for two tugs amounted to 30 thousand rubles. Добро пожаловать в мир сладких приключений с Sweet Bonanza ! Наши азартные слоты наполнены удовольствием и безграничными возможностями выиграть большие призы. Попробуйте удачу сегодня и окунитесь в мир сладких бонанз!