Part Maker Tutorial      

1. Part Maker Introduction    2. Geometry Files    3. Getting Started With Part Maker    4. Making Models in Part Maker   

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Geometry Files

GHS uses a multi-level scheme for organizing the model. The top level is when we view the whole model together and say 'this is a computer model of vessel X'. In practical terms, we deal with the whole model as a single file on the computer. This is called a GEOMETRY FILE, and it contains all of the information about the shapes, sizes and locations of the hull, appendages, tanks, etc.


Inside the Geometry File, you find the first level, which is the PART level. Here we have the parts of the model (namely the hull, tanks and compartments), which will need to be dealt with when doing calculations like loading and stability analyses. In GHS terminology, a part is classed as: 1) a HULL or displacer; 2) a TANK or container; or 3) a SAIL or superstructure element which neither displaces nor contains but only provides windage area.


Parts are quite often made up of more than one COMPONENT, some of which may be negative or deducting components.

That may seem like enough levels, but there is actually another level below the component level called the SHAPE level. Neither the part level nor the component level contain very much data. It is only when you get down to the shape level that you find things like stations and offsets. The reason for this is that we would like to avoid having a lot of redundant information lying around. In a steel ship, you need twice as much steel if you want to build a pair of tanks, port and starboard, even if they are mirror images of each other. In the computer, however, we can get by with just one set of offset data for both tanks as long as the program knows how to make a mirror image out of it.

A component does little more than point to a shape and tell whether it belongs to the port, starboard or both sides or if it is symmetrical about the centerplane. Since a component must point to one and only one shape, you can consider that the shape data really belongs to the component ... just remember that another component could be pointing to the same shape.

GEOMETRY FILE (Complete Vessel)
PART                                              PART
(HULL)                                             (DEEP1)
|                                                           |
(HULL.C)               (SKEG.C)                (THRUSTER.C)                    (DEEP1.S)               (DEEP1.P)
|                      |                               |                                               |                       |
       SHAPE           SHAPE                   SHAPE                                   SHAPE                   SHAPE
If you understood all of that, you should have no trouble understanding how to use Part Maker. At this point, it would be a good idea to read the first few pages of the Part Maker section of the User's Manual where these concepts are discussed in a little more detail. Maybe you are thinking that so much complexity is unnecessary for the type of vessels you deal with, or that this multi-level data structure is too much for you to handle right now. You can be sure that when you get down to punching the keys, it will be much easier than it seems now. And you certainly do not have to build a detailed model if you don't need one. What constitutes enough detail for your purposes is something that only you can decide.

Part Maker never forces you to put more complexity into the model than you want. But when you need an accurate accounting of free surface within tanks, or when you need to assess stability with flooding, or when you need to model semi-submersibles, dry docks and SWATHs, then Part Maker will literally save the day. In fact, it will make a job that was tedious to the point of being unthinkable with other methods easy and surprisingly fast.

Getting Started

1. Part Maker Introduction    2. Geometry Files    3. Getting Started With Part Maker    4. Making Models in Part Maker   

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