<< Click to Display Table of Contents >> Navigation:  Flexcom > Theory > Model Building > Vessels and Vessel Motions > Calculating Vessel RAO Response >
Flexcom Waves

One very important point to note is that in Flexcom all waves emanate from the origin. A number of examples of wave direction specification are shown in the first figure below. When defining an RAO in terms of wave heading, it is important to ensure that the wave directions specified using any of the various wave specification options produce waves that are, in fact, incident on the vessel between the vessel heading values specified – see the second figure below.

Examples of Wave Direction Specification

 

Wave Direction and Wave Heading

It is important to be clear on the difference between wave direction and wave heading. Wave direction is the angle between the direction of wave advance and the global axis system; this remains constant throughout an analysis. You specify wave direction data when specifying other wave data, such as amplitude(s) and period(s). Wave direction data is independent of RAO data, because of course an analysis with waves included does not necessarily include vessel motions (although it would in most cases).

Wave heading on the other hand is a method of defining the direction of wave advance relative to a vessel axis system. As such, wave heading definition is intimately tied up with the specification and use of RAOs.