BALLAST TANK

INTRODUCTION

Ballast tank is a very important part of any ship or submarine, It provides vertical stability against shifting of Center Of Buoyancy, when the ship or submarine undergoes loading and unloading process or maybe affected by other dynamical factors, such as ship approaching to shallow waters.

BRIEF CONCEPT OF CENTER OF BUOYANCY

When a body is submerged in a liquid, It gets bombarded by the liquid molecules from all sides. The vertical upward force that is exerted by the bombardment on the body, which balances the weight of the body is known as the Buoyant force. And like the Center of Gravity, The point or center through which this force acts is called as  Center of Buoyancy.

HOW DOES BALLAST TANK WORK 

A Ships body is strengthened by stiffeners, to add stiffness that make up the ship's hull as well as inner compartments. Any type of stiffener may be Floor or Stringer has holes that allow ballast water to occupy the ship's space uniformly.

The picture shown shows a Stringer as well as Floor connecting different Stringers. The Stringers can be identified by the plates having holes that is running from Forward portion or Front portion of the ship to the Aft or End portion of the ship. And the floors running transversely.

In the picture given below, the working of the ballast tank can clearly be illustrated. A ship needs to displace equal amount of water to that of its weight to keep it afloat. Therefore considering the cargo ship given below, when loading the cargo, its total weight becomes greater than the water displaced by the ship and thus to keep it afloat, the ballast water is pumped out until the added weight balances the displaced water weight. This process is reversed during unloading, and In this way the ship achieves vertical stability.