GHS Port Reference Center
Information for maritime designers, engineers and builders
Maintained by Creative Systems, Inc., Creators of GHS
Click here for information about GHS and other fine marine software.
Go to Main page

46 CFR 171.080 (f) (6) (iii)
    `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
    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
    report off
Add a free link to your site
Copyright © , Creative Systems, Inc.
Privacy policy