Hull GDI Calculator





This excel-based app allows you to estimate quickly the residual ULS (Ultimate Longitudinal Strenght)
after a damage (grounding) on the bottom has occurred.
With this excel app, a fast estimation in term of structural strength can be done,
without employing complex and time consuming tools (FEA, Smith Method)


1. Firstly,the Typology of vessel has to be identified with the relative main dimensions:

h Height of double bottom

B Ship’s Breadth

D Ship’s Depth

  • 2 The information of the relative ULS for the Vertical bending moment in Intact condition for Hogging or Sagging  have to be inserted by the user3 The information relative to the scantling in the INTACT and DAMAGED condition of the Inner and outer bottom has to be identified by the user (ONLY blue cells):
    3.1 The length and the thickness of every strake belonging to the Outer Plate of the Outer Bottom
    3.2 The bilge has to be inserted for SB and PB side
    3.3 The thickness and the length of every vertical girder of the Outer Bottom
    3.4 The Typology, the numbers, and the single area of the Long.Stiffener belonging to the Outer Bottom
    3.5 The length and the thickness of every strake belonging to the Inner Bottom
    3.6 The Typology, the numbers, and the single area of the Long. Stiffener, belonging to the Inner Bottom4 The results are shown in “Results” sheet. Here the Reduction of ULS is determined as well the GDI factor
    A pre-assessment is performed, in case the DAMAGE Area is bigger than the INTACT AreaLimitationsThe GDI app is suitable for Containership and Tankers.
    The GDI Spreadsheet is recommended to use in case of damaged TANKER/CONTAINER vessel. The maximum suggested range of application of GDI is 0.71.References[1]  J.K Paik,Do Kyun Kim,D.H Park, “A new method for assessing the safety of ships damaged by grounding,” International Journal of Maritime Engineering, vol. 154, pp. 1-21, 2012.
    [2]  J. K. Paik, in Advanced Structural Safety Studies With Extreme Condition and Accidents, pp. 94; 475- 477.
    [3]  Do Kyun Kim, Preben Terndrup Pedersen, Jeom Kee, “Safety guidelines of ultimate hull girder strength for grounded container ships,” Safety Science, vol. 59, pp. 46-54, 2013.
    [4]  Do Kyun Kim,Han Byul Kim, Mohd Hairil Mohd, Paik, “Comparison of residual strength-grounding damage index diagrams for tankers produced by the ALPS/HULL ISFEM and design formula method”.
    For feedbacks, write to [email protected]Version HistoryVersion 0.0
    Date 2-Jul-2020
    Notes First Release

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