Stability of Floating Vessels

Overview

Source: Alexander S Rattner and Kevin Rao Li Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA

The objective of this experiment is to demonstrate the phenomenon of stability of floating vessels - the ability to self-right when rolled over to the side by some external force. Careful design of hull shapes and internal mass distribution enables seagoing vessels to be stable with low drafts (submerged depth of hull), improving vessel maneuverability and reducing drag.

In this experiment, a model boat will first be modified to enable adjustment of its center of mass (representing different cargo loadings) and automated tracking of its roll angle. The boat will be placed in a container of water, and tipped to different angles with varying heights of its center of mass. Once released, the capsizing (tipping over) or oscillating motion of the boat will be tracked with a digital camera and video analysis software. Results for the maximum stable roll angle and frequency of oscillation will be compared with theoretical values. Stability calculations will be performed using geometric and structural properties of the boat determined in a computer aided design environment.

Procedure

1. Measuring maximum angle of stability

Select a small model boat. A relatively simple hull design is recommended to reduce analysis complexity in Sections 3 and 4.
Connect a lightweight brightly-colored vertical mast to the boat (blue recommended). The provided MATLAB code tracks the position of the mast in the video by looking for bright blue pixels in the image. If a different color mast is used, the imag

Results

Total mass (m, kg)	Center of mass (H_cm, m)	Center of buoyancy (, m)	Moment of Inertia (I_zz, kg m²)
0.088 Log in or to access full content. Learn more about your institution’s access to JoVE content here Application and Summary This experiment demonstrated the phenomena of stability of floating vessels and how ships can stay upright even with relatively high centers of mass. For example, in the representative results, a small model boat with a center of mass (H_cm = 5.3 cm) well above the water line (H_{water line} ~ 1 - 2 cm) could return to its upright position after being tipped to a ~25° angle. In the experiments, the maximum stable angle was measured for a model boat with different vertical centers Log in or to access full content. Learn more about your institution’s access to JoVE content here Tags Floating Vessels Stability Performance Metrics Staying Upright Positive Buoyancy Capsized Vessel Safety And Comfort Crew And Cargo Orientation Vessel Stability Tradeoff Design Optimization Fuel Efficiency Maneuverability Shape And Weight Distribution Experimental Testing Computer aided Design Software Buoyancy Gravity Object Orientation Skip to... 0:07 Overview 1:30 Principles of the Stability of Floating Vessels 4:49 Performing the Experiment 8:07 Numerical Approach to Design 11:33 Applications 12:37 Summary Videos from this collection: Now Playing Stability of Floating Vessels Mechanical Engineering 21.4K Views Buoyancy and Drag on Immersed Bodies Mechanical Engineering 29.3K Views Propulsion and Thrust Mechanical Engineering 20.6K Views Piping Networks and Pressure Losses Mechanical Engineering 57.0K Views Quenching and Boiling Mechanical Engineering 7.7K Views Hydraulic Jumps Mechanical Engineering 40.3K Views Heat Exchanger Analysis Mechanical Engineering 27.8K Views Introduction to Refrigeration Mechanical Engineering 24.3K Views Hot Wire Anemometry Mechanical Engineering 15.4K Views Measuring Turbulent Flows Mechanical Engineering 13.4K Views Visualization of Flow Past a Bluff Body Mechanical Engineering 11.0K Views Jet Impinging on an Inclined Plate Mechanical Engineering 10.6K Views Conservation of Energy Approach to System Analysis Mechanical Engineering 7.1K Views Mass Conservation and Flow Rate Measurements Mechanical Engineering 22.4K Views Determination of Impingement Forces on a Flat Plate with the Control Volume Method Mechanical Engineering 25.8K Views Privacy Terms of Use Policies Contact Us Recommend to library JoVE NEWSLETTERS Research JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive Education JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site Authors Overview Publishing Process Editorial Board Scope and Policies Peer Review FAQ Submit Librarians Overview Testimonials Subscriptions Access Resources Library Advisory Board FAQ ABOUT JoVE Overview Leadership Blog JoVE Help Center Copyright © 2025 MyJoVE Corporation. All rights reserved