Lengthening a ship

In some cases a ship has to be extended. In such a case a new hull shape has to be used either in the existing project or in a copy of the existing project. To use as much of the already created construction as possible, the existing blocks in the area where the lengthening is performed need to be shifted. Shifting a block will not change the contour or shape of the construction, it will only shift items' positions.

In CADMATIC Hull, the construction of a block is stored in the construction database belonging to that particular block. For each construction part the relations used in defining the part as the resulting calculated contour (in absolute coordinates) will be saved in the construction database. Relations of a part can be other construction parts (even from other blocks), the hull shape, grid values and fixed values.

The calculated contour is used when the part is presented in a view and when the part is used as a relation of another part. When the relations of a part are modified, the contour will automatically be recalculated and stored in the construction database.

There are also cases in which the relations of a part do not change, but a recalculation of the parts might still be necessary, for example, when using a new hull shape. When a part is recalculated, the system will evaluate the currently stored relations of the part and the new calculated contour will be stored.

Lengthening types

There are three different situations depending on the type of lengthening/extension.

• Situation A – Only the position of the construction in the ship changes, the frame numbering stays intact. That is. the ship is lengthened starting at a certain length and no new frame numbers are added, but the frames after the lengthening position are shifted with the size of lengthening.
• Situation B – Both the position and the frame numbering change. That is, new frame numbers are added in the part that is added.
• Situation C – The shape at the new position changes.

In principle there is no need to recalculate the construction in the shifted blocks in situation A or B. However, it is recommended to recalculate or at least check and possibly adjust the relations of the construction items in the block(s) that were next to a block(s) which were not shifted.

In situation C, all constructions in the shifted blocks need to be recalculated, but this should be done after all blocks have been shifted.

Drawing properties after lengthening a ship

The properties of the drawings (views) in a block such as the view plane and/or the areas have to be modified manually after shifting a block. The 2D drafting items present in the drawings such as text, dimension and drawn lines have to be shifted manually over the same shifting value as used during the shift block action.

In case of shell views created in the Shell application, the part numbers of the shell plates might have to be placed again.