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Finding the angle theta3, where A2 = A1 as in the RINA Cargo Loss criterion.
    `Finding the angle Theta3, where A2 = A1 as in the RINA Cargo Loss criterion.
    `In this run file, the TCG of the vessel is set to create conditions during
    `lifting and after the cargo loss.  Since the effect of TCG varies with the
    `cosine of the heel angle it is equivalent to setting a cosine based heeling
    `When using this method, the run file should either set up actual loading
    `conditions with and without the crane load, or use a heeling moment to represent
    `the counterballast weights.  Keep in mind that the equilibrium angle during
    `lifting is saved as variable t1 and is necessary to evaluate the criteria.
    proj theta3
    read subdivy
    crt(1) Vent 25a, 5s, 11 /sym
    draft 6
    vcg 8
    solve weight lcg
    macro findt3            `finds Theta3, then evaluates RINA Cargo Loss
     macro t3               `incrementally adjust t3 until t < 0.05
      lim title --Find Angle Theta3----------
      lim(1) res ratio from abs {t1} to abs {t3} > 1
      ra /lim /noprint
      \limmarg: {limmarg};  t3: {t3};  t: {t}  `prints iteration history
      if {t} < 0.005 then exit
      if {limmarg}>0 then set t3={t3} minus {t} else set t3={t3} plus {t}
      set t={t} times 0.5
      exit t3
     variable t3=30         `theta3-terminating angle for res ratio limit
     variable t             `amount to increment or decrement t3
     set t={t3} div 2
     lim off
     \\Theta3 is {t3:1} degrees, as demonstrated below.\
     ra /lim:att /graph:none `/stop:fld
     if {t3}>30 then set t3=30 | ,,
     \Theta3 not to be taken greater then 30, therefore Theta3=30\
     lim off
     limit title RINA Pt E, Ch 19, Sec 2: 2.2.3
     lim(1) res ratio from abs {t1} to FLD or RA0 > 1
     lim(2) angle from abs {t3} to FLD or RA0 > 20
     ra /lim:att /stop:fld
    tcg=.5                  `Simulate lifting condition - hook load on starboard side
    variable t1={heel}      `Equilibrium heel angle during lifting
    tcg=-1.5                `Simulate dropped load condition - counterballast on port side
    `Setting angles direction and sign of starting angle, t1, if RAH to port.
    `(Righting arm direction is determined by equilibrium angles before and
    ` after the hook load is dropped.  When the righting arm is to port, ABS
    ` angles are the opposite of the normal sign convention, which is +=STBD.
    ` Angles * is not sufficient to direct the righting arm direction for all
    ` combinations of equilibrium with and without lifting.)
    if {t1}>{heel} then angles 0 -5 ... -30 | set t1=minus {t1},,
                   else angles 0  5 ...  30
    print preview
    report off
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