Large angle stability righting arm curve

This is an Excel Program for the calculation of the GZ curves and large angle stability properties of a wall-sided vessel.  The program can be used to obtain reasonable estimates the GZ Curves of many vessels.  The results are exact for rectangular parallelepipeds (brick-shaped) vessels.  Try the online calculator below. Edit only the yellow cells. Specify one, two ore zero raked ends. They will be built with the same dimensions.

Large Angle Stability Calculator

hydrostatic stability vessel geometry

Simple Vessel Geometry Input

Input to large angle stability hydrostatic analysis

The barge length, beam and depth are input, together with draft and KG (the distance from the keel to the VCG). The length of any forward rake and the depth of the headlog are input, or no forward rake may be specified. An aft rake identical to the forward rake may be specified. These 8 terms, plus the mass density of the water, enable the program to calculate small angle hydrostatics for the vessel and to calculate the large angle stability (righting arm) curve. The vessel is constrained to an even keel, zero trim, condition.

Large Angle Stability Results

Numerous checks against various stability criteria are made, including those from 46 CFR 173 for Protected Waters and for Exposed Waters.  Wind heeling calculations are included and Residual Ara Ratio Checks are made.  Residual Area Limits with Crane Load, NAVCRANECEN INSTRUCTION 11450.2, March 2013 are made.

large angle stability results with charts showing residual areas

Wind Areas and Wind Heeling

Simple wind area geometry input is provided. Accurate calculation of the projected areas to wind forces is made at large angles. ABS height coefficients are automatically used in the calculation of large angle stability residual areas and area ratios.

See our other online calculators, including our Catenary Anchor Chain Length Calculator.

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