This data record is invalid if the convolution method is used, i.e. CONV option is on, in a time domain analysis. The drift frequency damping will default to zero. If additional damping is to be added for the drift frequency motion, one should use the frequency independent damping defined by the FIDD data record (The FIDA/FIDD Data Record - Frequency Independent Additional Diagonal Added Mass and Damping ).

      2   5  7   11         21        31        41
    - --- -- ---- ---------- --------- --------- --------- ---------
   |X|   |  |DGDP|XXXXXXXXXX|         |         |         |         ...
    - --- -- ---- ---------- --------- --------- --------- ---------
       |  |   |                  |         |         |         |
       |  |   |                  |-------------------------------------
       |  |   |                  |
       |  |   |                  |_(1)Up to 6 Damping Coefficients(6E10.0)
       |  |   |
       |  |   |_Compulsory Data Record Keyword(A4)
       |  |
       |  |_Optional User Identifier(A2)
       |
       |_Compulsory END on last data record in data categoy(A3)

(1) These 6 values specify the Drift Damping of the structure indicated by the Data Category Keyword, at each of the 6 degrees of freedom of motion.

Typical values of damping for a ship structure in the surge,sway and yaw direction range between 1 and 10 per cent of critical. For freedoms where there is no mooring stiffness, the critical damping is not defined. In this event, reference should be made to the literature.