Resistance prediction

Hello all,

I need a small clarification as to what the below text actually mean

1 {0.93 ( / )
0.521448 0.6906
0.92497
1 13 12
C C lcb
k c c B L
P P
R
− − +
+ = +
−
In this formula, CP is the prismatic coefficient
based on the waterline length, L and lcb is
the longitudinal centre of buoyancy forward
of 0.5L as a percentage of L??

Please kindly tell me what the highlighted text means

My vessel is a catamaran and am calculating resistance for a demi hull...

My vessel length is 18m...and my LCB demi hull is 8.9m from aft

thank you

 

Longitudinal centre of buoyancy expressed as a percentage of L, measured from the mid-ship (0.5 L). If it is forward of the mid-ship, then it is a positive value - otherwise it is negative.

For example:

L = 80 m
Xlcb = 3 m aft of the midship​

gives:

LCB = -3/80 = -0.0375​

or, in percentage:

LCB = -3.75%.​

The value is negative because it is aft of the 0.5L.


Another example:

L = 60 m
Xlcb = 2 m forward of the midship​

gives:

LCB = 2/60 = 0.0333​

or, in percentage:

LCB = 3.33%​

The value is positive because it is forward of the 0.5L.

Hope it helps.