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Naval Architecture & Ocean Engineering

EN342: Ship Hydrostatics and Stability

Catalog Description

EN342: Ship Hydrostatics and Stability (3-2-4)

Theories and procedures for predicting a ship’s hydrostatic response to various conditions are addressed. Methods for computing the stability characteristics of both intact and damaged ships are studied. Floodable length computations are taught. Stability and subdivision criteria are explained. The lines plan for a hull form is developed and analyzed.


  • Introduction to Naval Architecture (Gillmer and Johnson, 1982)
  • Practical Naval Architecture, Volume I (Johnson, Compton, White, and Miller)


  1. Describe methods for calculating a ship’s hydrostatic properties, including calculation of areas, volumes, centroids, and important hydrostatic parameters such as Δ, LCF, LCB, KB, KM, TPI, MT1”.
  2. Draw and interpret a ship’s lines drawing.
  3. Calculate and assess basic intact, impaired, and damaged stability characteristics of a ship. Specifically, calculate metacentric height (GM), calculate and plot righting arm curves (GZ), and calculate changes in drafts and trim for weight additions, removals, or shifts.
  4. Describe basic methods to calculate a ship’s damaged stability and trim and determine required watertight subdivision, including development of floodable length curves.
  5. Describe basic design criteria for assessing intact and damaged stability of naval and merchant ships, including intact and damaged heeling moment and righting energy criteria, and extent of damage and watertight subdivision criteria.
  6. Describe basic characteristics of submarine hydrostatics, stability, and trim, including the equilibrium polygon, and basic hydrostatic and hydrodynamic effects on depth control.


  • EN247, Principles of Naval Architecture and Marine Engineering, OR
  • EN245, Principles of Ocean Systems Engineering

Class Topics

  1. Naval Architecture Terminology
  2. Hydrostatic Pressure and Archimedes’ Principle
  3. Centers of Buoyancy, Flotation, and Gravity
  4. Ship’s Hull Form, Form Coefficients, Lines Drawing & Table of Offsets
  5. Changes to Center-of-Gravity Due to Weight Additions, Removals, and Shifts
  6. Initial Stability and Metacentric Height
  7. Impaired Stability: Free Surface, Grounding/Drydocking
  8. Longitudinal Stability and Draft Changes: Weight Additions, Removals, and Shifts
  9. Numerical Integration of Areas, Volumes, and Centroids
  10. Intact Overall Stability and Righting Arm Curve, Cross-Curves of Stability
  11. Weight Changes on Righting-Arm Curve
  12. Curves of Form, Bonjean Curves
  13. Inclining Experiment
  14. Intact Stability Criteria
  15. Damage Stability: Added Weight and Lost Buoyancy Methods
  16. Load Lines and Floodable Lengths
  17. Subdivision Criteria
  18. Submarine Hydrostatics, Stability, and Trim

Laboratory Projects

  • FFG-7 Trim Lab
  • FFG-7 Inclining Experiment
  • FFG-7 Righting-Arm Lab
  • FFG-7 Flooding Experiment
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