GHS-SK Optional Module

The General HydroStatics SeaKeeping Module "SK" is designed to provide the GHS user with an integrated, general-purpose solution for seakeeping and hydrodynamic analyses. SeaKeeping is the result of significant in-house development work, and while it offers many features that may be found in other motions codes, it is also unique in many respects. Integration within the GHS environment also means calculations may be performed using existing geometry files, loading conditions, and run files. This translates to minimal additional user input, unmatched flexibility in its market segment, and ease of use.

SeaKeeping offers an excellent and economical solution for seakeeping and hydrodynamic analysis that is well suited to many applications. Some of the more common use-cases include:
SeaKeeping Features
The module offers users the following features: Don't see a specific feature on the list? Contact Customer Support to inquire about current and prospective feature updates. SeaKeeping is always being updated and improved.

SeaKeeping Output
Seakeeping calculations create a lot of data, which is both a necessity and a curse when you are trying to review results. Seakeeping output is designed to make it as easy as possible to reference specific RAOs or response results for certain Critical Points or heading/speed combinations (a.k.a. Cases) without omitting important supporting information. SeaKeeping reports are organized according to the following structure, with options to include or omit various sections:

  2. Summary of general input parameters, including method type, meshing parameters. coupling parameters, and a table of seakeeping geometry part\component names and types.
  4. Table of user specified Critical Points, overall vessel CG, and any optional derived response points (SHW, MSI).
  5. CASE(S)
  6. Case number, case-specific wave heading and ship speed
    1. Wave Components
    2. Summary of overall wave/spectra type, wave samples, sampling method parameters, and numerically derived variance and significant wave height. Also includes tabulated wave period, frequency, LWL/WvLen, encounter frequency, ordinate, and amplitude for each wave component.
    3. RAOs and Phase Angles (Position, Velocity, and/or Acceleration)
    4. Tabulated RAOs and phase angles for all modes for each Critical Point. Also includes a plot for each mode, with results for all Critical Points plotted together.
    5. Response Statistics (Position, Velocity, and/or Acceleration)
    6. Tabulated response statistics for all modes for each Critical Point. Includes variance (m0, m2, m4), average periods (ZUC/Maxima), RMS, average, significant, average maxima, and optional confidence/interval extreme amplitudes.
    7. Derived Responses (Optional)
      1. Slamming
      2. Deck Submergence/Shipping Water "SHW"
      3. Motion Sickness Incidence "MSI"
    8. Case Summary Table (Optional)
    9. Table of user requested absolute response amplitudes for all modes for each Critical Point. Displays the response for the preceding case.
  7. POLAR PLOTS (Optional)
  8. Polar plots for each user requested response for each Critical Point for all modes.
  9. LIMIT PLOTS (Optional)
  10. Polar limit plots for each user defined dynamic limit over all cases.
  12. Table of overall user requested absolute response amplitudes and corresponding case numbers for all modes for each Critical Point. Displays the maximum over all cases.

To help parse especially large runs, SeaKeeping offers optional case-specific or overall summary tables which display user requested position, velocity, and/or acceleration amplitude components in the x (Surge), y (Sway), z (Heave) translational directions, and the X (Roll), Y (Pitch), Z (Yaw) angular directions. These tables are an ideal "one-location" reference point for design values or initial review, and are always located at the end of each reported case. Automated response and limit polar plotting is also available to further aid in the review process.

In addition to comprehensive reports, SeaKeeping offers six (6) optional comma-separated-variable (CSV) data files that include any of the information found in the report in a convenient form for input into spreadsheets, third-party programs, or further post-processing by run-files.

What Makes SeaKeeping Different?
SeaKeeping is a unique and powerful analysis tool. Below is a selection of white papers that provide a more complete introduction to the software, various use cases, and why SK is different from the competition.

GHS-SK: An Integrated, General-Purpose Approach to Seakeeping and Hydrodynamic Analysis
(Abstract) The General HydroStatics SeaKeeping software module, referred to in short as "SK", is Creative Systemsí entrant into the world of hydrodynamics. Introduced in January of 2018, the module aims to provide users with an integrated, general purpose approach to seakeeping and hydrodynamic analysis. This paper is a moderately technical introduction for the interested individual or prospective SK user. After some introduction, the overall focus will be on the four (4) main areas that make SK unique in its class: Automation, Customization, Technical Capability, and Development & User Support. While some theoretical content is presented here, those specifically interested in a deeper mathematical basis of the module are invited to contact Creative Systems Inc. for a copy of the SK Userís Manual.

Get Access to a Trial Version
If you are interested in testing the SeaKeeping Module, contact sales to inquire about a temporary license. We will work with you to set up a trial period that meets your evaluation needs.

Validation Studies
A number of core validation studies, including coefficients, forcing, RAOs, relative motions, and accelerations, may be found here.

A collection of common questions from SK users may be found at the bottom of this page.

Papers Featuring SK
A newly published paper in the September issue of Ocean Engineering, by GHS SK developer, Kyle Marlantes - "A Fully-Coupled Quadratic Strip Theory/Finite Element Method for Predicting Global Ship Structure Response in Head Seas" -

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