Marine Engineering Specialists -- Bentley Systems has acquired Ultramarine's MOSES Software [ Press Release ]
By loadout, we mean the process of moving a structure from a set of skidways on the land to a cargo barge. Normally, the barge is placed some fixed distance away from the land skidway and the structure is skidded along the land skid. At some point, part of the structure will cantilever over the gap between the barge and the land. The structure is moved further until part of it is over the barge. At this time, the barge ballast is changed so that the barge partially supports the structure. Now, the structure is skidded further off of the land and onto the barge. Throughout this process two things are important:
  • The ballast in the barge, and
  • The stresses in the structure.
These two things are intimately related. Even if the structure is completely on the barge, it is possible to ballast the barge so that the structure becomes overstressed.

Instead of considering the problem as a single difficult one, it is normally separated into two problems:

  • Analyze the structure with a set of stiff supports which model the barge skidways, the land skidways and the gap between the two.
  • Design a barge ballast plan for the loadout so that the barge has zero deflection when the reactions of the first analysis are applied to it. The barge ballast condition must be computed for quite a few intermediate positions between when the barge first picks up load, and when the structure in completely on the barge.
Since the barge has essentially zero deflection under the reactions computed assuming zero deflections, the results of the two analyses should be comparable. At the conclusion, however, one should check a point or two to make sure that nothing was omitted.