Handling Vessel Data

Slide 1 of 14www.orcina.com OrcaFlex User Group, 2010

Handling Vessel Data

Introduction

• The vessel object is complicated

– Different calculation options

– Different data types

required from varied

sources

• Guidance on how to import the different data types required



Overview of Vessel Data

3 main methods for importing diffraction data:

• Manual: Copy/paste (not advised!!)

• Semi-automatic: Marked-up text file

• Fully Automatic: AQWA and WAMIT

This data is manually set



Units and Conventions

• OrcaFlex has its own units and conventions system. Diffraction data may have different units or conventions

• AQWA / WAMIT import: data automatically converted to match OrcaFlex units and conventions at time of import

• For marked-up text files:– If units and conventions are specified then

OrcaFlex converts these as above

– If units and conventions are not given then the data is imported unconverted



RAO Data Import

• Either Displacement or Load form

• AQWA / WAMIT files:

– read by OrcaFlex (‘Import Hydrodynamic Data’ button)

– either .lis (AQWA) or .out (WAMIT) file (note that

WAMIT .sif file is not supported)

• Otherwise you need a ‘marked-up text file’,

with appropriate header for data type:

– *** OrcaFlex Displacement RAO Start ***

– *** OrcaFlex Load RAO Start ***

• Use ‘Check RAOs’ button for sanity check



Wave Drift (QTF) Data Import

• Again can be imported either:

– From a full AQWA/WAMIT import

– Or from a marked-up text file

• Previous releases required non-dimensional

QTF data

• In v9.4 QTF data must be dimensional:

– Units are specified in the marked-up text file

– Old binary (.dat) OrcaFlex files will be

automatically converted



Stiffness, Added Mass & Damping

• Again, data is either:

– Imported directly from AQWA/WAMIT

– Or from a marked-up text file

• OrcaFlex requires dimensional data. Source

data often non-dimensional or different units:

– AQWA / WAMIT handle automatically at import

– Marked-up files. Conversion is done with scaling

factors in the marked-up file. Examples for

MOSES, ARIANE/HYDROSTAR and WADAM in

v9.4 help



Structure

• Much less data is required here

• Mass and mass moments of inertia:– AQWA / WAMIT automatically set if available

– For a marked-up text file, these need to be manually added

• CoG:– OrcaFlex uses this as a common reference origin

for AQWA / WAMIT import so must be manually set

– For a marked-up text file, this is not set and needs to be manually added



Hydrodynamic & Wind Damping

• This data is not automatically imported (but

much less data required here)

• So copy/paste or manual entry

• Loads due to relative flow past the vessel

• Data sources:

– OCIMF (Tanker vessel forms, with minimal topsides)

– Wind tunnel tests (both above and below waterline)

– Semi-analytical or CFD methods



Drawing

Visual only, no impact on calculations or results

Import from .x file in

shaded views

Copy/paste or

manual entry



Things to look out for…(1)

AQWA / WAMIT:

• Set CoG location in OrcaFlex before import

• Symmetry convention must be set manually

• Equilibrium position:

– Must be set manually for WAMIT import

– Z-position imported for AQWA but not heel/trim

• Import file should have single vessel data

• Some AQWA / WAMIT files not in format

OrcaFlex expects. OrcaFlex warns and may

not import



Things to look out for…(2)

Marked-up text files:

• Some data needs to be set manually:

• With forward speed, Moses/Ariane present

encounter frequency. OrcaFlex needs zero-

forward speed data

• Hydrostar recently introduced a WAMIT

output format.

RAO, QTF and Phase Origins Stiffness Matrix

Symmetry Convention Equilibrium Position



Marked-Up Text File Example(s) …(1)

There are examples of how to mark-up the data

for some common diffraction packages in the

OrcaFlex help, see:

System Modelling – Data and Results | Vessel Types |

Importing …. (there are a few different pages covering

the different data types)

A typical generic file is shown in the next slide



Marked-Up Text File Example(s) …(2)



Summary

• If you have data from AQWA or WAMIT data

then simply import these directly

• If you have data from another package then

used marked-up text files:

– These can be imported individually on each

vessel type data form

– Or you can merge all the individual text files into

one large text file and import directly through the

‘Import Hydrodynamic Data…’ button

Handling Vessel Data

Documents

handling vessel datamarked

handling vessel datathings

orcaflex user group

text files

text file

set manually

manually set

orcaflex