When the weight of the water displaced by an object is the same as the weight of the object the the object is nuetrally bouyant. In other words it floats, or is suspended, at a point between the surface of the water and the bottom of the container or ocean bottom. Port Left side of ship. When the weight of the water displaced by an object is more than the weight of the object then the object is positively bouyant. In other words the object floats.
Pressure Is the thrust or force per unit area.
Is the water tight volume of a boat or ship that is above the waterline. Starboard Right side of ship. Stern Back of ship. Variable Ballast Tank or VBT Is a ballast tank whose volume is adjusted to give a selectable amount of bouyancy. Typically a VBT has three valves.