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Based on ISO power yacht stability standards. Design category A assumed.
    `Based on ISO power yacht stability standards
    `Design category "A" assumed
    
    MACRO ISOY-FLD
     PAGE
     \\----\
     \ISO POWER YACHT - DOWNFLOODING (6.1)\
     \Downflood Height (6.1.2)\
     \Downflooding Angle (6.1.3)\
     \----\
     \\\\>>>> Heel induced by passenger crowding <<<<\
     \\
     CRTPT OFF
     CRTPT (1) "%1" %2 %3 %4
     HEEL = 0
     SOLVE
     STATUS WEIGHT, CRTPT /NOREF
    
     Part = hull
     Refpt = %2, %3, %4     `<--- Downflooding point
     VARIABLE h
     SET h = {Lh} DIV 17
    
     \
     \(6.1.2) Downflood height above waterplane = {height}\
     \This height must be > {h:2} (hull length/17.0)\
     mac pass
      \PASSES\
     //
     mac fail
      \FAILS!\
     //
     IF {height}>{h} THEN .pass ELSE .fail
    
     LIM OFF
     LIM TITLE DOWNFLOODING ANGLE (6.1.3)
     LIM ANGLE FROM EQU TO FLD > 25
     LIM ABS ANGLE AT FLD > 30
    
     VARIABLE t
     SET t = 24 MINUS {Lh}
     SET t = {t} TIMES {t} TIMES {t}
     SET t = {t} DIV 600
     SET t = {t} PLUS 10
     LIM ANGLE AT EQU < {t}
     \\\Max heel angle at equilibrium = 10 + (24 - {Lh})^3 / 600 = {t:2}\
     PAGE
     RA 0 5 /LIM:ATT /GRAPH:NONE
    /
    
    
    MACRO ISOY-WW
     PAGE
     \\----\
     \ISO POWER YACHT RESISTANCE TO WAVES & WIND (6.3)\
     \Rolling in Beam Waves & Wind (6.3.1)\
     \----\
     \\\\>>>> Heel induced by wind <<<<\
     \Heeling moment = {HMMT}\
     \\
     HEEL = 0
     SOLVE
     HMMT REPORT
     \
     STATUS WEIGHT /NOREF
    
     VARIABLE x
     SET x = 10 DIV {DISPL} PLUS 24
     \\\\\Roll angle = 24 + 10 / {DISPL} = {x:2}\
     ROLL = {x}
     HEEL = *-ROLL
     LIM OFF
     LIM TITLE ROLLING IN WAVES & WIND (6.3.1)
     LIM RATIO FROM ROLL TO ABS 50 OR FLD > 1
     PAGE
     RA 0 5 /LIM:ATT
    /
    
    MACRO ISOY-W
     PAGE
     \\----\
     \ISO POWER YACHT RESISTANCE TO WAVES & WIND (6.3)\
     \Resistance to Waves (6.3.2)\
     \----\
     \\\\
     HEEL = 0
     SOLVE
     STATUS WEIGHT /NOREF
    
     MACRO B
      LIM RA AT MAX TO ABS 30 > 0.2
      \\Area requirement is 0.2 m-rad.\
     //
     MACRO C
      VARIABLE x
      SET x = 30 MINUS {HEEL} TIMES 0.057 PLUS 3.15
      LIM AREA: DEGREES
      LIM AREA FROM ABS 0 TO MAX > {x}
      \\Area requirement = 3.15 + ( 30 - {HEEL} ) x 0.057 = {x} m-rad.\
     //
     LIM OFF
     LIM TITLE RESISTANCE TO WAVES (6.3.2)
     LIM ABS ANGLE AT MAX > 15
     RA 0 5 ... 120 /STOP:MAX /HOLD /NOPRINT
     \\\\Angle of maximum righting arm = {HEEL:2} degrees.\
     IF {HEEL} < 30 THEN .C ELSE .B
     HEEL = 0
     SOLVE
     PAGE
     RA 0 5 /LIM:ATT
    /
    
    macro sample
    read my.gf
    units mt           `<--- Metric units required
    
    variable Lh
    set Lh = 29.6      `<---- Put length of hull here
    
    weight = 145.0     `<------ full load weight w/o passengers
    lcg = 14.339       `<------ full load lcg w/o passengers
    vcg = 1.804        `<------ full load vcg w/o passengers
    
    ADD "28 People up dk"   2.100, 10.67, 2.92, 5.953 `<--- Offset loading
    ADD "57 People mn dk"   4.275, 15.13, 2.74, 3.591 `<--- Offset loading
    
    .ISOY-FLD "Engine vent" 17.09, 1.52, 3.75        `<--- Downflooding point
    
    ADD "28 People up dk"  *, *, 0.0, * /nowarn `<--- Normal loading
    ADD "57 People mn dk"  *, *, 0.0, * /nowarn `<--- Normal loading
    
    HMMT =  17.017  `<--- Wind heeling moment
    .ISOY-WW
    HMMT OFF
    
    .ISOY-W
    /
    `.sample
    
    

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