Experiment 5: Stability of Floating Bodies


Laboratory experiment 5 is an exercise in hydrostatic. It is designed to demonstrate the stability of a floating cylinder and to familiarize the student with the concept of buoyancy, metacenter and metacentric height. It is also an experimental verification of the theory presented in the textbook.

The center of the buoyancy of a floating body depends on the shape of the body and on the position in which it is floating. If the body is disturbed by a small angle of heel, the center of buoyancy changes because the shape of the submerged volume is changed. The point of intersection of the lines of action of the buoyancy force before and after heel is called the metacenter (M) and the distance between the center of gravity (G) and M is called the metacentric height (GM).

For stability the metacentric height GM must be positive. Stability (restoring force) increases with increasing GM.


The objectives of this experiment are:

1. To determine how the floating characteristics of a pontoon changes as it is loaded with weight and tilts.

2. To determine the metacentric height of the pontoon by measurement and calculation.


As a conclusion, this experiment was successfully carried out even though the data collected are a large difference between the value of metacentric height obtained by extrapolation on a graph and the calculated metacentric height. There are some error take place during the experiment was carried out which could give effect to the data obtained. Firstly, error due to the observer or parallax error. This error take place during the observer take the reading of the depth of pontoon submerged in water and the angle tilt. Thus, to overcome this error, the eye of the observer must be 90o perpendicular to the measurement in order to get an accurate result. Next, the disturbance due to the water and air also can affect the measurement taken. Thus, to overcome this error, the experiment should being done in ideal condition so that an accurate measurement will be obtained.


1. http://www.engineering.uiowa.edu/~cfd/pdfs/57-020/stability.pdf

2. http://atapaje.blogspot.com/search?updated-min=2008-01-01T00:00:00-08:00&updated-max=2009-01-01T00:00:00-08:00&max-results=18


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