The Free Water on Deck

Abstract

The effects of free water on decks are considered in relation to the transverse stability of ships.
First, the weight and the inclining moment of free water contained in a open rectangular tank are calculated for general cases and their graphical representations are obtained in a compact form.
Second, the general characters of stability curves of ships with free water on decks are explained and the calculating method of the curves is described, when the freeing ports are neglected but the houses, hatch coamings etc. are taken in count.
Examples of stability curves are shown for a rectangular ship (calculated) and a model of a steel fishing vessel (measured), in which the existense of negative stability range is ascertained.
Finally, an approximate integration of the rolling equation is worked out to see a character of ships motion.
In a inclining experiment, the changes of the trim of about 2 degrees are obtained, of which the effects upon transverse stability will be made clear in the near future by model experiments.