engleski

The effect of voluntary speed reduction criteria on attainable ship speed

The reasons for ship speed reduction in a seaway may generally be divided into two categories: natural reasons, such as the added resistance due to wind and waves, change of wake field and loss of thrust ; technical or “design” reasons that are controlled by the shipmaster, such as very large motion amplitudes, velocities and accelerations, slamming, green seas, overload of the main engine. The natural reasons influence the ship speed at relatively low significant wave heights. 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. There is no strict rule that determines under which conditions the shipmaster would reduce the speed, so various authors have proposed different criteria. This paper presents a study of the effect of the various voluntary speed reduction criteria to attainable speed of ship on seaway.

voluntary speed reduction; seakeeping criteria

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