Hi TIG,
I sent you a PM some time ago. Did you have a chance to have a look at it?
Thanks
JM

I have done more experiments.
In the last one, I open both files, each in a separate session of SU.
I open a third session of SU, to have an empty workspace.
In the Superstructure file, i have produced four separate composite C of G's, related to four major classes of objects. I copy only these four composite C of G's, and paste them in place in the empty design.
I do the same for the Hull file. I have there 2 composite C of G's that I copy, and paste in place into the new design.
Thus the new design only contains six composite C of G's.
When I try to combine these composite C of G's in the new design, I can only get a result with the four C of G's of the superstructure file. The two from the Hull file won't combine when I select them and choose the Composite C of G menu option.

If I do it the other way round, and copy the Composite C of G's from the Hull file first, only those would combine. I am unable to combine those that were pasted later.

Is this a clue to the reason of the problem?

jgb : thanks for the advice. Unfortunately, the pasting way is not successful either.
In the meantime, I have also tried doing this :

• Open SU, a new design is created (an empty one)
• import one file
• import the other file

It does not work either. One intersting thing is, like in my above post, that the total weight is that of the C of G that belongs to the file imported FIRST. T can confirm this, as I tried both ways.

Still at my wit's end...

Hi,
I have a problem with the composite C of G.
I am designing a houseboat, and I have designed the hull and the superstructure in two different files.
In each file I have calculated the individual C of G's and blended them all to get a global C of G. This worked well.
Now I need to merge the two files, to calculate the C of G of the whole boat. What I do is :

• Open one of the files (e.g. the Hull)
• import the other file (e.g. the superstructure).

The imported items are automatically grouped as a component. I explode it.

When I try to combine the C of G of the Hull with that of the superstructure, I get a composite C of G very close to that of the hull, with the weight of the hull only.

I have tried to do it the other way round :

• Open the superstructure file
• Import the hull

If I try to produce the composite C of G of both, I get a C of G close to that of the superstructure, with the weight of the superstructure only.

To make a long story short, apparently the addition of the weights (and the calculation of the location of the composite C of G) fails with the imported C of G.

Could you help me?
Jean-Marc

Hi,
I have just installed CofG in Trimble Sketchup 8 and it works fine.
However I have a special need. I am designing a houseboat, and I need to calculate the global center of mass of it.
For the parts that are made with materials, like walls, floors, the plugin is ok. But for components that I have added as a whole, like a diesel genset, or a washing machine, I do not know the equivalent density.
What I would like to do is to assume the component is homogeneous, and to assign it a weight.
I have studied how CofG works, and I noticed that each CofG group is given 2 attributes : volume and weight. I have tried to edit the weight attribute, to see what happens. Of course, the text associated with it must also be manually edited.
What surprises me is that whenever I change the weight attribute, the composite calculation command fails. It says "calculating", but produces nothing : no new CofG object is created. What prevents it from working?
Actually what I would like is an additional command with a new dialog to calculate the CofG: instead of entering the density, I would like to be able to enter the total weight, and have the command place the G point at the center of mass of the group or component. In other words, once the volume is calculated, and the center of mass found, assign the weight attribute with the weight specified in the dialog.
Is this feasible?
Jean-Marc