Vessel Degrees of Freedom |
 
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Vessel Degrees of Freedom |
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An attached vessel has six degrees of freedom (DOFs), three translations and three rotations. These are defined in Flexcom in terms of a local vessel coordinate axis centred, as noted above, on the reference point. The vessel direction is initially vertical. Motions in this direction represent vessel heave, and rotations about this axis correspond to vessel yaw. The local and directions form a plane that is horizontal in the initial vessel position. Motions in the vessel and directions correspond respectively to vessel surge and sway, while the respective rotations give roll and pitch. These directions and motions are illustrated schematically in the figure below. Note that vessel RAOs are normally defined for all six degrees of freedom.
Vessel Degrees of Freedom