Current Loads |
 
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Current Loads |
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Current loads, denoted 
, 
and 
, are calculated using:
(1)
where:
•
, 
and 
are the current coefficients in surge, sway and yaw respectively for an equivalent current incidence of 
•
is the water density
•
is the vessel draft
•
is the vessel beam
•
is the length between perpendiculars which is the sum of 
and 
•
is the distance from the vessel centre of gravity to the forward perpendicular
•
is the distance from the vessel centre of gravity to the aft perpendicular
•
is the equivalent current velocity
The equivalent current incidence 
is obtained using:
(1)
and the equivalent current velocity 
is given by:
(2)
where 
and 
are as previously defined.
You can specify that a certain fraction of Munk’s yaw moment be subtracted from the current loads applied to the vessel. Munk’s moment is calculated using:
(3)
where the various symbols are as previously defined. Additionally, you can specify that a certain fraction of Molin’s yaw moment is added to the current loads applied to the vessel. Molin’s moment is calculated using the following expression:
(4)
where:
•
is Molin’s yaw coefficient
•
is the transverse component of the relative fluid velocity at a distance 
from the vessel centre of gravity, given by 
•
is the total relative fluid velocity at a distance y from the vessel centre of gravity, given by 
•*MOORED VESSEL is used to define a moored vessel and its associated properties. Specifically, the TYPE=GEOM inputs are used to specify vessel geometrical data such as draft, beam, length between perpendiculars etc.
•*CURRENT COEFF is used to specify current coefficients used to determine the current loading on a floating body or moored vessel.
•*MOMENTS is used to specify the value of Molin’s yaw coefficient for a moored vessel, and also to specify the fractions of Molin’s Moment and Munk’s Moment that are applied to the moored vessel.
If you would like to see an example of how these keywords are used in practice, refer to D01 - Moored Vessel.