The meta centric height apparatus is used to measure the static stability of a floating body. Simply put, the apparatus is used to calculate the distance between the center of gravity of a floating body and it's meta center.
Meta center is defined as the point after which a floating body starts oscillating when tilted by a small angle. The distance between the meta center of a floating body and it's center of gravity is called meta centric height. A larger meta centric height generally implies enhanced stability against overturning
The meta centric height apparatus is widely used in the shipping industry for simulating real environments on which a floating body has to perform. The simulation is done through developing a model of the floating body and checking it's stability using the apparatus after proportionally tweaking water levels and pressure according to the weight of the model.
Components of Metacentric Height Apparatus
A meta centric height apparatus generally consists of
A horizontal guide bar
Set of weights
A cross bar with two movable hangers
A graduated arc
Procedure for Measuring Metacentric Height Using an Apparatus
A model of a ship or any other floating body is allowed to float in a small tank that has a transparent side.
Removable steel strips are placed in the model for the purpose of changing the weight of the model.
The weight displacement is measured using a scale.
For tilting the floating body model, a cross bar with two movable hangers is provided with the apparatus.
The angle of tilt can be measured on the graduated arc by means of a pendulum.
By equating the results of all above parameters, the meta centric height of any floating body can be achieved.
Common Sources of Error To Be Careful About
The meta centric height apparatus is very accurate in taking measurements. The measurement errors happen largely because of human faults rather than because of any drawback in the apparatus. All in all, there are mainly two sources of errors about which one should be careful while taking measurements.
One is the error in measurement of angle as a result of the set up not being brought to rest completely before taking measurements. The other error commonly arises while noting down the exact angle of the tilt.
Salient Features of Metacentric Height Apparatus
The apparatus is easy to operate and requires minimal maintenance.
It has optimal resistance against corrosion.
The apparatus has enhanced durability, making it very reliable.