Question:

As we know, Ship's Block Coeff. is calculated based on the molded hull form. ie, Cb= Volume/(Lbp*B*d), where Volume is molded volume and B is molded Breadth. In order to get the ship's exact displacement, I use a 'shell' command in Part maker. As the ship's volume will have changed, it will no longer be 'MOLDED Volume' of the hull. The Cb value calculated according to this volume should not be correct.

Is there any solution to this problem?

How can I handle 'shell plate' as appendage that will not affect the hull volume?

Answer:

In order to get the form coefficients for the molded hull you have to create a molded version of the geometry file. Here is one way to go about it:

READ geofile
ENTER PM
MODIFY HULL.C
SHELL 0
/
WRITE TEMP.GF
QUIT PM
REPORT file1.pf
\\Note: The following curves of form are based on the molded hull.\
COMPONENT HULL\HULL.C /FORM
REPORT OFF
CLEAR
ERASE TEMP.GF
READ geofile.gf
REPORT file2.pf
...

Note that the curves of form go onto a separate report (file1). The same report file could be used for the subsequent calculations by making use of the /APPEND feature of the REPORT command.