GHS LIMIT commands based on Navy stability criteria
Intact severe wind and wave:
HMMT WIND /C2
ROLL = 25
LIM RISE > 0.667
LIM RESIDUAL RATIO FROM ROLL TO RA0 > 1.4
Lifting, Crowding & Turning:
HMMT = x /CS
LIM RISE > 0.667
LIM ABS ANGLE AT EQU < 15
LIM ABS RATIO FROM EQU TO RA0 > 1.667
Towline adds to Lifting:
LIM ANGLE FROM MAX TO ABS 40 OR FLD > 0
LIM ABS RATIO FROM EQU TO ABS 40 OR FLD > 1.667
LIM ABS ANGLE AT EQU0 < 15
LIM RESIDUAL RATIO FROM ROLL TO ABS 45 OR RA0 > 1.4
LIM RESIDUAL RATIO FROM ROLL TO FLD OR RA0 > 1.4
`roll angle depends on displacement
LIM RA AT MAX > 0.25 `(units must be feet)
These interpretations of the Navy criteria are not necessarily appropriate for every type of
vessel in every loading condition and in all types of service. Additional limit commands
and/or changes to the parameters as shown above may be needed in order to guarantee
A value attained for the RISE limit (A) can be converted to the value of the ratio of righting
arm at equilibrium to righting arm at max (B) as follows:
B = 1 / (1 + A)
For example, A = 0.667 yields B = 0.6.
A value attained for the ABS RATIO limit (A) can be converted to the value of the ratio of
residual area to total area (B) as follows:
B = 1 - 1/A
For example, A = 1.667 yields B = 0.4.
To allow for off-center weights, the transverse center of gravity can be set to an appropriate
value. If it is desired that the transverse center of gravity of the total weight (including tanks)
be 0.05, the following command can be used:
WEIGHT (TOTAL) *, *, 0.05, *
This will set the transverse componenet of the light ship CG such that the overall TCG comes
out to be 0.05. Since the MAXVCG command ignores the TCG (as well as tank loads), this
will not affect MAXVCG curves.
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Creative Systems, Inc.