Abstract
A method is presented for evaluating the performance of piston internal combustion engines used as the main engines on sea-going ships and acting in typical operating conditions. These conditions are described taking into account the performance area of engines of this type. The presented method provides opportunities for calculating the numerical effect of the action using the integral calculus. The above effect is presented as a physical quantity expressed by a number with the metric unit called the joule-second. Proposed is the use of types of integrands (which are functional dependences of the energy converted in these engines on time) which make it possible to use the second fundamental theorem of calculus justifying the use of the Newton-Leibniz formula. The object of the analysis is the process of changes of the energy converted in the internal combustion engines during their operation, described with the aid of a deterministic model of the real process taking into account its sample realisation.