MS Plan B: Evaluating Stability and Structural Integrity of a Modified Cargo S

Jacob Dennis
Masters Student
Department of Ocean & Resources Engineering
University of Hawai’i at Manoa


**This defense will be held in person (POST 418) and Zoom**
Meeting ID: 835 7663 5393
Passcode: JacobMS
Zoom link: https://hawaii.zoom.us/j/83576635393


Modifying existing ships can be a cost-effective way to meet new operational demands without the time and expense of building entirely new vessels. One common modification is increasing the vessel’s length to expand cargo capacity. However, such changes can significantly impact a ship’s stability and structural integrity, raising important safety considerations.
This project investigates the effects of a 52-foot hull extension on a Mariner-class cargo ship originally built in the 1950s. Using hull lines from Applied Naval Architecture, the original ship geometry was reverse engineered in Maxsurf and extended by inserting a parallel midbody section. Initial stability was analyzed using the U.S. Code of Federal Regulations, including evaluations of large angle stability, floodable length, and limiting KG to ensure compliance. Dynamic response simulations were performed in OrcaWave and OrcaFlex using Pacific Ocean wave data to assess ship motions in a 1-year design storm. A midship section was designed based on ABS Rules for Building and Classing Steel Vessels and analyzed using the finite element software HyperMesh to confirm the structural adequacy of the extended hull.
Results showed that the extended vessel met all regulatory stability requirements and demonstrated improved survivability in both intact and damaged conditions. The hull extension led to higher righting arms, increased floodable length, and a more favorable limiting KG curve, especially in lightship and fully loaded conditions. Dynamic simulations confirmed that the modified ship remained well within safety margins during the design storm, with roll and pitch responses staying below down flooding thresholds. Structural analysis of the midship section showed that the existing scantlings were sufficient to handle the increased bending moments introduced by the added length, and no modifications were necessary. Overall, the analysis confirmed that the proposed hull extension is a safe and effective way to enhance the cargo capacity and operational utility of the original vessel.

Event Sponsor
Ocean and Resources Engineering, Mānoa Campus

More Information
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