The word ‘hydrostatics’ is made up of two parts: ‘hydro’, which means water, and
‘statics’, which means characteristics or study of whatever it is that is stationary. It
is quite clear, therefore, that by hydrostatics we are talking about the properties of
stationary water. A ship normally floats in water, and for the water to be stationary,
it is essential that the ship does not move. One can see then that ‘hydrostatics’ deals
with physical systems in static equilibrium. Hydrostatics in naval architecture is
concerned with forces, moments and all other properties of stationary ships.
This obviously implies that there is ‘hydrodynamics’ as well. This sounds really
interesting, but anything dynamic is quite a lot more complicated to study and
understand than those which are static. In fact, it is not too difficult to see that statics
is a special case of dynamics, where the motions happen to be zero.
Let us now go back to still water and consider hydrostatics. Remember that the
water is not moving. This means there is no wave and no current, and no wind
either, since wind will cause waves and make the ship move, which in turn will
disturb water. This cannot represent the reality. We all know that even ‘flat calm’
mirror-like water surface has ripples on it. Why then are we talking about hydrostatics in naval architecture? An immediate, and not altogether flippant, answer is that it is simpler that way! We can understand quite a lot about water if it does not move.