A new theory of minimum stability,a comparison with an earlier theory and with existing practice

Abstract

The author has already presented his new theory of minimum stability for the intact and damaged ship, and his own programmes for use on computers, at a Yugoslav and at two foreign symposiums.

To the best of the author’s knowledge, only Russian scientists are studying this field, very intensely. They developed a theory that there are several possibilities to obtain a diagram of minimum stability, the most important of which are the ‘diagram of minimum moment’ and of ‘minimum work’. It is becoming more and more important, and essential for a damaged ship, to take the trim into account in stability calculations, generally known in the world only to specialists. It thus seems to the author that even in discussions on the following presentations the very simple essence of that new theory, which is to take the trim into account in the best possible way, has not been understood.

Here we shall try to give an even simpler explanation and also a short description of the mentioned Russian theory, because the author considers that the new theory shows both the mentioned diagrams to be identical, and even represented by a third, which belongs to the second group of those Russian propositions, under the new name ‘diagram with excluded component in the direction of the principal axis of maximum inertia’. In this way the solution is completely determined, which is very important. It seems to the author that the fact that several solutions formerly existed is one of the main reasons why these Russian results, over twenty years old, have not yet entered international stability regulations.

We will also make a comparison with principles applied in computation with trim in systems accessible to the author, like ‘VIKING’, ‘COMPUTAS’ etc. Those principles are not completely exact, but are, it seems, acceptable for practice to date.