Demonstration calculator
Barge stability calculator
Intact stability of a trapezoidal pontoon is determined from its hydrostatics, the resulting righting-lever curve, and the applicable intact-stability criteria.
At each heel angle, the equilibrium draft is obtained from constant displacement, and the centre of buoyancy is determined from the actual immersed volume. Consequently, the GZ curve can be continued beyond deck-edge immersion by integrating the changed immersed geometry; deck-edge immersion does not, by itself, terminate the hydrostatic calculation. For a shallow pontoon, however, deck-edge immersion may occur at a relatively small heel angle and can become an important limiting condition, depending on the applicable stability criteria and downflooding arrangements.
A demonstration of method. It models a bare pontoon with no superstructure, no downflooding openings, no free surface and no wind heeling arm. A stability booklet for your vessel includes all four; we prepare it and support it through the classification society’s review.
About the calculator
Intact stability of a pontoon barge
A pontoon barge carries deck cargo high above a shallow hull, so its stability is set by the metacentric height and by how soon the deck edge goes under as it heels. The calculator finds the draught from the displacement, the metacentric height from the waterplane, and the righting lever curve from the immersed volume at each heel angle, holding the displacement constant. The curve is then checked against the Intact Stability Code 2008 criteria for areas, the angle of maximum righting lever and the static heel under wind.
Taking it further
When a full stability study is needed
A loading manual, a tow approval or a heavy-lift operation needs the barge's actual lines, its tanks and free surface, the cargo's wind area and the operation's own criteria. These are calculated as a customised analysis, and the result is documented for the surveyor or the warranty surveyor.