Allowable KG & Stability Macros

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This sample shows how to use our automated stability macros to assess the stability of a single condition, or to find an allowable condition. The data file is much like that for the other samples here, except that it contains the line:

use_mac stab which loads the two stability macros: STAB_OK and KG_ALLOW.

STAB_OK produces the righting arm, heeling arm, and area ratio curves for the draft specified. Since the righting arm is based on the equilibrium of the buoyancy and weight of the vessel, the vessel weight must have been previously defined. This is accomplished here with the stanza:

   $
   $*********************************     set transit condition
   $
   &INSTATE -CONDITION 7
   $
   $*********************************      compute weight for cond.
   $
   &WEIGHT -COMPUTE  5 32 85 85

Here, we perform stability checks with the two commands:

   $
   $**************************************      check one intact
   $
      stab_ok 7 2.5 10 -wind 100 -yaw 0
   $
   $**************************************      check one damaged
   $
      stab_ok 7 2.5 10 -wind 100 -yaw 0 -damage 5p

These two checks are identical, except that the first one checks intact stability for a draft of 5 feet, while the second one checks stability with compartment 5p damaged. There are other options for STAB_OK, so check out the general documentation mentioned

The command:

    kg_allow -draft       5       \
             -wind        100  50 \
             -damage      5p      \
             -yaw         0 45    \
             -i_ar_ratio   1.4 \
             -i_arm_ratio    0 \
             -i_down_h       0 \
             -i_gm           0 \
             -i_are@marm     0 \
             -i_are@dfld     0 \
             -i_are@40       0 \
             -i_arm_ar       0 \
             -i_zcross      90 \
             -i_theta1      90 \
             -i_range        0 \
             -i_ang_diff     0 \
             -i_dang_t1      0 \
             -i_dang         0 \
             -i_ang@marm     0 \
             -d_ar_ratio     0 \
             -d_arm_ratio    0 \
             -d_down_h       0 \
             -d_gm           0 \
             -d_are@marm     0 \
             -d_are@dfld     0 \
             -d_are@40       0 \
             -d_arm_ar       0 \
             -d_zcross      90 \
             -d_theta1      90 \
             -d_range        0 \
             -d_ang_diff     0 \
             -d_dang_t1      0 \
             -d_dang         0 \
             -d_ang@marm     0

Produces an allowable KG for a draft of 5 feet.