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General HydroStatics
Ship Stability Software |
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Command of the Week
(New or interesting aspects of GHS that you may not know about) |
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SEAKEEPING (part 3)
(Requires GHS version 16.02 or later with SeaKeeping Module) |
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Typically, FV.GF or TANKER.GF steal the show, and very little attention is given to the humble and hardworking BARGE.GF. We thought it was time to highlight one thing BARGE.GF does very well: carry ISO containers.
It is expected that a scaled-up version of BARGE.GF will be hauling sixty, 40-foot ISO containers on its way up to Alaska. The containers are to be loaded in a 5x6x2 arrangement as shown below. |
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| The expected loading condition is given by the STATUS report shown. Note that the lightship gyradius is specified and each individal container gyradius was included using the ADD /BOX parameter. |
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| BARGE.GF will be transiting some distance offshore, so a Narrow-Band Bretschneider wave spectrum with a characteristic period of 12.0 seconds and a significant wave height of 7.2 feet is specified: |
wave (spe) BR 12.0, 7.2, N |
| In the region of interest, the barge will be transiting at a speed of 6 knots with an expected wave heading of 135 degrees. The fastening points for container #1 and #60 are defined by critical points (1) through (8), so we include these points in the seakeeping analysis. We are interested in the most probable extreme acceleration response amplitudes in a 24 hour period, so we also specify a confidence level of 99% over the desired period and include a summary table of the accelerations. |
sea /head:135 /speed:6 /crt:1,2,...,8 /samp:30 /conf:99,24 /sum:A /gu |
| After running SEAKEEPING with the stated parameters, the resulting Absolute Response Summary table is given below. The surge, sway, and heave (x, y, and z direction) translational acceleration amplitudes are summarized for each fastening point. The rotational accelerations are also given for completeness. |
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Finally, BARGE.GF is getting some well-deserved attention. And judging from the accelerations, it looks like all sixty containers will be onboard when BARGE.GF reaches its destination.
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