Effect
of advance speed
Effect
of advance speed 
is determined
by a tank test in short waves.
Fig.1.
Flow chart of calculation for 
Effect of advance speed is obtained as follows:
(1)
: Measured added
resistance due to waves
: Added
resistance due to ship motion
: Froude number
The experimental results of effect of advance speed 
are shown below.
Fig.1. Container ship
(length 300m)
Fig.2.
PCC (length 190m)
Fig.3.
Panamax Bulk Carrier (length 217m)
The figures show that 
is a good approximation
at the speed of actual operation.
Actual operation
Container ship , PCC: Fn=0.2-0.25
Panamax Bulk Carrier: Fn=0.1-0.15
The coefficient of advance speed in directional waves is determined
by the same procedure
as mention above. The experiments in directional waves
are carried out and the following relation between the coefficient
of advance speed and the bluntness coefficient is
obtained.
Fig.4.
Relation between coefficient of advance speed and bluntness coefficient
From the figure the following formula is derived for
practical use.
for 
>0
in case; 
in case; 
: a functional symbol of the constant part
: a functional symbol of slope part
: the coefficient of advance speed determined by the tank
test
: the bluntness coefficient in heading waves
: the bluntness coefficient in directional waves
The coefficient of advance speed derived from the tank
test contains the effect of
hull form above water line though the line Fig.4 is
derived from conventional hull forms.
