Three motion components are described in the following articles, namely:
'Vessel Offset' - which is used to specify the mean (static) offset that is to be applied to a vessel in an analysis.
'Vessel Motion' - which is used to specify the dynamic motions of a vessel, including first order (RAO) motions and second order (drift) motions. There are two main options available in PipeLay for the specification of vessel motions. With the first option, the vessel motions are defined by separately specifying (a) the vessel RAOs and (b) low frequency drift motions, while the second option allows the vessel motions to be read from a file containing a time history of the combined (first and second order) vessel motions. The Vessel Motion component is referenced by the Vessel component, and can optionally reference the RAO Conversion component, if RAOs need to be converted to the standard Wood Group format.
'RAO Conversion' - which is used to define the various conventions that apply to a particular set of vessel RAO data. RAO data is not input directly into the PipeLay UI; RAOs are instead specified in an ASCII data file, and the name of this RAO file then becomes the UI input. This has the added advantage that the same file can be used in any analysis with this vessel, without the need for constantly specifying the same data. As RAO data can use many different conventions; the RAO Conversion component allows you to define these conventions for a particular file. Note that you can have a number of different vessels in your project file, so you can likewise have multiple RAO Conversion components.