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An approach to converting general cargo ship to cement carrier is analysed in the present study, emphasising the structural aspects of the conversion. A comprehensive re-appraisal of the conditions of the ship hull, considering her history and present condition of the structure, is provided. Two case studies are presented where the strength assessment has been performed using 2D sectional and 3D finite element models, generated according to the available hull drawings and thickness measurement reports. The results of the two studies are interpreted with respect to the structural modifications carried out during the conversion process, and some general conclusions are drawn.

The most important degradation effects of ship structures are corrosion and fatigue cracks. Both of these aging effects have clear consequences of increasing the level of stresses and degrading the strength of ship structures for almost all relevant failure modes. This study presents an overview of some recent developments on the aging effects on the ship structural integrity. The analysis of the thickness measurements has been undertaken to improve understanding of the corrosion degradation phenomena and to develop prediction models of aging effects suitable for practical applications in the ship structural design and analysis. The study also deals with the application of the non-linear finite element analysis as a suitable tool for a collapse assessment of uniaxially loaded plates and stiffened panels of ship structures weakened by non-uniform corrosion degradation and fatigue cracks. Experimental studies have also been reviewed to better understand the recently found degradation of mechanical properties of corroded steel, while theoretical calculations have been performed to evaluate consequences of such degradation on the ship structural integrity.

When the ship is caught in heavy seas, there are two manoeuvres that the shipmaster can undertake to avoid excessive ship motion and hull damage: changing course or voluntary speed reduction. This paper presents a study of the effect of the various voluntary speed reduction criteria to attainable speed of ship on seaway. The speed loss is calculated by taking into account wind and wave effect on ship speed, the engine and propeller performance in actual seas as well as the mass inertia of the ship. The attainable ship speed for ship in head, following and beam waves by accounting for voluntary speed reduction is estimated for various significant wave height. The criteria of slamming, deck wetness, propeller emergence, excessive accelerations and roll are taken into account. The impact of variations of the limiting values of certain criteria due to which the captain intentionally reduces the ship speed is analysed and discussed.