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Ship data

In this tab the specifications of the moored vessel or SPM buoy can be defined by choosing a HYD-file and, if required, scale this HYD-file to the required dimensions.

 

HYD-file

The "Ship data" tab provides information on the selected hydrodynamic object. This object is described in a HYD-file. A HYD-file contains the results of diffraction calculations: added masses, potential damping, first and second order wave force transfer functions. This file is obligatory. The HYD-file can be imported / exported / deleted with the file buttons. The standard HYD-files are located in the aNyMoorDb folder. A specific HYD-file can be provided by MARIN on request. Multiple hydrodynamic objects can be included in one HYD-file which are represented by a body index.

The ‘Hyd file’ button imports and interprets the hydrodynamic file of a floating object and shows its relevant data in the GUI. Not all data is always available in the hydrodynamic file. This is due to the fact that some data items are defined in the IDENT (info) section of the HYD-file. Note that this section is free format. The application tries to search for most appropriate keywords in this section and shows the retrieved data in the panel. Once imported the body index (default=1) can be selected from the required hydrodynamic object.

Because of the interpreted data from the IDENT section, it is advised to check the imported data with the data in the preview windows panel when selecting a hyd-file.

 

Scaling of a vessel 

The original value of the displacement is used to determine the scaling ratio. For instance if a new displacement of 270,000 m3 is entered whereas the original value of the displacement was 200,900 m3  then the scale factor will be 1.1. This scaling applies in the 3 dimensions. The hydrodynamic data file (HYD-file) will be scaled with this factor according to the Froude law.  Note that this means that all data are adapted (including all hydrodynamic characteristics such as KMt, KMl, GMt and GMl). More information about the scaling relations is given in Vessel scaling rules.

When the scaling factor is outside the range of 0.7 to 1.3, a warning is issued that the scaling is exceptional and that the scaling results cannot be trusted anymore. In that case it is advised to use another, vessel specific HYD-file.

The check boxes enable the user to set the value and neglect the scaled value.

All scaled edited values must be greater than zero.

 

Vessel scaling rules

The vessel properties are scaled according to the Froude law. The scale factor λ depends on the displacement: 

λ = (Displacement required/Displacement from hydfile)1/3

The properties are scaled as follows

Property

Scale factor 

 Draft λ
 Beam λ 
 CoG position -X, Y, Z λ
 Wind area λ2 
 Displacement λ3 
 Radii of inertia λ 
 Waterline area λ2 
 Transverse metacentric height λ 
 Longitudinal metacentric height λ 
 Hyd-file – wave frequencies λ 

 Hyd-file – 1st order wave forces – surge, sway, heave

λ2 

 Hyd-file – 1st order wave forces – roll, pitch, yaw

λ3 

 Hyd-file – added masses – surge, sway, heave

λ3 

 Hyd-file – added masses – roll, pitch, yaw

λ5 

 Hyd-file – potential damping – surge, sway, heave

λ 

 Hyd-file – added masses – roll, pitch, yaw

λ 

 Hyd-file – 2nd order wave forces – surge, sway, heave

λ 

 Hyd-file – 2nd order wave forces – roll, pitch, yaw

λ3 
 Damping file - linear damping surge, sway, heave  λ 
 Damping file - linear damping roll, pitch, yaw  λ
 Damping file - quadratic damping surge, sway, heave  λ2
 Damping file - quadratic damping roll, pitch, yaw  λ5

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