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Virtual Technical Meeting Sponsored by Hampton Roads and Capital Chapters

October 21, 2026, 12:30 - 1:15 pm EDT

Topic: SAWE Paper No.  3854: The Impact of Changing Test Weight Vertical Center of Gravity on a Shipboard Inclining Experiment

Presented by: Alan Bryden, Naval Sea Systems Command

When: Wednesday October 21st, at 12:30 pm EST

Abstract: Changes to the vertical position of the test weights during the course of an inclining experiment affects the experiment results. In most cases, weight movements are perpendicular to the ship’s centerline plane and do not change in height. However, this may not be practical, or it may be more economical to raise or lower the elevation of the weights during the inclining experiment. It is up to the naval architect to determine the magnitude of this effect and whether it should be included in the calculations. This paper assists the naval architect in consideration of alternative means of performing an inclining experiment without sacrificing accuracy. This paper takes a geometric approach to the derivation of the GM equation and factors in the adjustment due to vertical weight movements. “Small angle” assumptions for the GM calculation remain and the effect of changes to those assumptions are not addressed in this paper. The primary drivers of error when moving the weights vertically are the magnitude of the angle of inclination and the ratio of the distances of the vertical movement with respect to the horizontal movement. This paper presents a correction factor tool for naval architects to determine the magnitude of the effect and how to include the effect in the results if necessary.