ShipmoPC

ShipmoPC is a seakeeping prediction code developed by Defense Research and Development Canada (DRDC) which has been validated against model data for a wide variety of ships including offshore supply vessels, FPSO's, coastal defense vessels and barges, icebreakers and naval ships. 

The code is based on two-dimensional strip-theory and solves for frequency domain seakeeping parameters (motions, accelerations, relative motion, shear force and bending moments). Boundary element method or the Lewis forms (conformal mapping) method is used in ShipmoPC to determine hydrodynamic properties of the ship hull. 

As strip theory forms the basis of ShipmoPC, common assumptions for this method are adopted. The fluid is assumed to be incompressible, inviscid, and non-rotational.  Most importantly, motion amplitudes and velocities are assumed to be small.

ShipmoPC can be used to analyze mono-hull ships of all sizes whose length to beam ratio is larger than 4 (to comply with the strip theory assumptions). The code is also more accurate for moderate ship speed (Fr< 0.35-0.4) and sea state up to sea state 6. Outside of these ranges, results from ShipmoPC can still be used for comparison purposes or as initial estimates.  Moreover, it can be used in fatigue analysis as load predictions are reliable in lower sea states.

Outputs from ShipmoPC are ship motion and load predictions including the following: 

  • Ship motions in six degrees of freedom in regular and irregular seas(RAOs and RMS)
  • Motions at user-specified locations
  • Still water and wave induced load assessment
  • Deck wetness, slamming occurrence, slamming pressures, and human tolerance factors (MII, tipping and sliding)