Theory and methods for calculating the inertial-braking characteristics of a ship


Yevgeniy Kalinichenko

One of the most serious problems of modern navigation is the accident rate that occurs due to inept or belated maneuvering of ships. As a result of accidents in the world, more than 200 ships sink every year and every fourth receives significant damage.

Full-scale tests show that the stopping distance of large-tonnage ships turn out to be much less permissible, and shipbuilders are able to significantly reduce the astern power of such ships, making them cheaper at the expense of safety.

The low accuracy of inertial-braking characteristics is mainly due to unqualified field tests. Analysis of graphs and tables based on the results of such tests show that the spread in the values of inertial-braking characteristics for ships of the same type reaches 30%, and in some cases even more. In many tables and graphs, inertial-braking characteristics are expressed in relative values and are not suitable for direct use when maneuvering a ship. Finally, even when graphical and/or tabular maneuvering information is available on the navigating bridge, it is difficult to use it when maneuvering a ship at night.

The research carried out by the author results in:

– creation of an alternative computational method for determining the inertial-braking characteristics of the ship, suitable for use on any on-board computer;

– development of an improved methodology for calculating the path and time of acceleration and braking of the ship in various ahead motion modes;

– development of a methodology for taking into account the influence of a passing and opponent current on the length of the stopping distance of the ship;

– development of methods for solving applied problems, ensuring a decrease in the accident rate of ships during maneuvering.

The obtained methods include the development of theoretical foundations, mathematical models and comparison of the calculated inertial-braking characteristics of ships with the data of a full-scale experiment. For the first time, to derive the calculated formulas for the time and stopping distance, theorems are used on the change in the momentum and kinetic energy during accelerated and decelerated motion of the ship. In the course of the study, the problems of calculating and formalizing the inertial-braking characteristics of the ship are being comprehensively solved. For the first time, the hypothesis that the nature of the change in the thrust force of the propeller during reverse can be approximated by linear equations has been substantiated and confirmed. The general results are used to calc