This article presents selected results of investigations on adverse events of ships throughout one year. The in- vestigations included mainly merchant vessels used to transport bulk material and heavy objects. Ships have been divided into functional systems and elements and into navigational and machine parts. An attempt was made to classify the causes of accidents and evaluate material losses. The quantitative analysis of the causes of the events leads to different conclusions than those reached on the basis of the analyses of losses. Although the failures on-board the vessel occurred more frequently, the costs of machine adverse events were larger. The most critical consequences was fire of a ship caused by loosening of the bleed screw of the fuel filter. Auxiliary engines of the vessel were operated in different external and internal conditions, and were fed by distillation fuel. As a consequence, the evacuation of the crew and fire suppression were required, using the CO 2 installation of the ship. The ship was stopped and deprived of its primary sources of electric energy. An analysis of the event was along with the elaboration of a plan of preventive measures. The results should be useful for selecting the monitored diagnostic objects of vessels.