Long Term Prediction

Once a short term prediction has been performed, Hydro can calculate a long term seakeeping prediction using voyage and wave data specified by you.

Before a long term prediction can be performed, you must specify details about the voyage to be undertaken using the Long Term Calculations dialog. See Seakeeping Dialog - Long Term Tab a more detailed discussion about entering data into this dialog.

Irregular response results for a selected speed are evaluated using a standard set of sea states. The long-term seakeeping assessment is then computed using the current long term data. The latter consists of the Voyage data and the criteria set for each of the motions to be analyzed. Any motion response that has been calculated in the short term calculations can be assessed by the long term assessment routine.

The wave data supplied with Hydro contains data for a small number of North Atlantic Sea areas taken from Hogben et al., References 37. Additional sea areas can be modelled by importing a file that contains long term wave statistics for several sea areas. It is your responsibility to ensure that any sea area in the voyage file exists in the wave data file. This wave data file is converted from an ascii file to the associated direct access binary file upon initializing the long term calculations. Alternatively, the binary file may be specified directly, avoiding this conversion.

The format of the wave data file is given in Wave Data File Structure.