`46 CFR 171.080 (f) (6) (iii) requires the area between equilibrium and
`downflooding or the second intercept to be > 0.0025 (equ - 1) m-rad.
`This variable area requirement can be calculated and used in the limit
`definition.  Since the limit is static after the limit command has been
`issued, it will not serve for maximum VCG calculations.  But it can be
`applied to individual cases where the heel angle at equilibrium is known.

`The following run demonstrates how this can be done.

proj 171080f6

`Create a simple hull with compartments sufficient for this example:
enter pm
units mt
create hull
ends 0 100
top 14
bot 0
out 15
margin 0.5
/
create cmpt1.s
ends 40 50
inb 10
fit hull
/
create cmpt2.s
ends 50 60
inb 10
fit hull
/
write
quit pm

report /nograph

`Derive a weight and CG:
draft 8
vcg 8
solve weight, lcg

`Define a point of downflooding:
crtpt = "Downflooding point" 70, 15, 15

`Define a heeling moment (wind and/or passengers):
hmmt 20000

`Flood two compartments:
type (cmpt1.s,cmpt2.s) = flood

`Issue the limits:
limit (1) angle at EQU < 15
limit (2) angle from EQU to RA0 > 20
variable A,H
solve `(finds the equilibrioum heel angle)
set H = ABS {HEEL} minus 1
set A = {H} times 0.0025 `(this assumes metric units)
limit (3) area from EQU to RA0 or FLD > {A}

\
\Equilibrium heel angle = {HEEL:2} degrees\
\Area required = 0.0025 * {H:2} = {A:4}\
\

`Calculate and evaluate the righting arm curve:
ra /lim

view
report off