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Weight Distribution Calculations in ShipWeight

The following attempts to describe how weight distribution is calculated inShipWeight. In general, ShipWeight approximates the distribution for each individual

weight item to either a uniform, triangular or trapezoid distribution. These individualitems are then added together making up the total accurate distribution. Theaccurate distribution can be converted to a distribution of stations or bars.

Consider the following weight items:

Nr Weight LCG LCG_min LCG_max

1 10000 50 0 100

2 6000 40 20 60

3 2000 30 10 40

4 2000 58 50 70

In ShipWeight, the distribution of these items will individually be represented like this:

When ShipWeight calculates its accurate distribution, the items are added together.

Compare the colors in the individual representations with the colors of the accuraterepresentation to locate each weights items contribution to the total curve.

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The user may choose to represent this curve in stations. ShipWeight calculates the

stations by dividing the accurate curve into the number of stations to be plotted.Each share of the accurate curve is integrated giving the area under the curvebetween the stations. Next this area will be represented by a station or bar with thesame area as the curve area it replaces.

This secures a one to one relationship in area between the accurate curve and thestation curve. Further, this means that the area contribution from individual itemswhich distribution is covering more than one station will be split into appropriate partsin each station. This secures the best possible conversion between accurate andstation curve.

See figure on next page representing the station version of the curve. Again, thecolors will help compare the curves to visually inspect how conversion takes place.

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In both cases, the area under the distribution curve equals 20 tons. The figure belowshows the accurate curve drawn in red with the station curve superimposed and

drawn in green. This shows how the curve is transformed and the area preserved.

Of course, the same reasoning is also valid with any other number of stations, notjust 10. The figures below shows same principles for the distribution curves as

discussed above, only this time with a 20 station curve.

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Exporting weight distribution

Pushing the Print/Export button in the dialog makes it possible to send the curve to aprinter or file, either graphically or numerically. It is also possible to export the weightcurves in formats to be read by GHS, Tribon, NAPA and AutoShip.

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