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. |
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proj crane `A crane barge energy calculation simulating the sudden loss of a hook load `ignoring damping -- following 46 CFR 173.025. `Create a simple rectangular barge hull: units lt enter pm create hull ends 0 100 top 6 bot 0 out 30 / write quit pm report `Lightship weight & CG: draft 4 vcg 12 solve weight, lcg `Add counterbalance and hook loads: boom "counter" 100 50 0 15 20 -90 0 boom "load" 40 50 0 11 80 90 10 `Macro to show initial status: macro stat1 solve page 75% `minimum percent of page free to continue printing on page. \\\===== Before hook load is dropped =====\ status / .stat1 `Delete hook load: delete "load" `Macro to do calculations for the present case after dropping load: macro stat2 solve trim `solve without changing heel \\\===== After hook load is dropped and before heel changes =====\ status page \\\ \ Note: The following righting arm curve represents heeling to port after \ the hook load is dropped. ra 0, -2, ... -30 /area:1-RA /stop:RA / .stat2 `An equivalent method using heeling moments: delete all weights add "counter" 100 50 0 15 `on centerline add "load" 40 50 0 24.89 `on centerline hmmt 1151.38 /c1 `<-- load minus counterweight .stat1 delete "load" hmmt -2000 `/c1 `<-- counterweight only .stat2 `Finding max. VCG that meets energy requirement, `assuming maximum initial heel angle of 3 degrees: lim area from ABS -3 to RA0 or FLD > 7.0 angles 0 2 vcg = 0 `Compute max VCG curve given a range of drafts: page maxvcg 3 3.25 ... 5 `Find max VCG in present condition: st solve angles * ra/lim solve maxvcg /fixdir `Keeps the heel direction from changing when solving for maximum VCG `Verify max VCG: page 75% `minimum percent of page free to continue printing on page. \\--- At maximum VCG ---\ ra /lim /stop:ra print preview report off end |
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