Principle Of FlotationĪccording to Archimedes principle when we submerge a substance / object in fluid there is apparent loss in its weight due to upward buoyant force. The buoyant force or buoyancy is caused due to fluid pressure acting on the opposite side.Ĭonsider an object A which is submerged in a water to a depth of “h” distance: This is the same reason why you feel lighter in a swimming pool or a ship floats but nail sinks. In short it is the ability of an object to float caused by the upthrust force which when is equals or more then its weight will float. It is equals to the weight of the volume of fluid displaced by the object. It is the upward force exerted on the submerged or partially submerged object in a fluid. Let us first give you a quick reversion of the parent topic “buoyancy”. It is this reserve buoyancy which then converts into buoyancy and stabilizes the ship preventing it from sinking.Ī ship would simply sink if the lose in buoyancy due to extra weight added to the ship unless when excess of reserve buoyancy is available to compensate for the losses.īut before you learn in detail about the reserve buoyancy and its critical role in ship stability. When we add more weight to the ship (cargo or crew) it tends to sink downwards as it looses some of its buoyancy. The distance between the top deck plate to the waterline on the ship side.

Thus many a times it is also termed as the free board. In short it is the watertight volume of the ship above its waterline providing additional buoyancy. The term reserve buoyancy refers to the volume of enclosed space or the part of ship above the waterline that can be made watertight. Without which you simply cannot understand practical operation of ship and its seaworthiness. Reserve buoyancy is a key concept of ships stability lessons.

Ship stability formula