losing data

[Dirk]

Hallo everybody,

I made a rough design of a sailboat, and after that a weight calculation.
To check a few things, I made a copy of the file.
Weight was still the same as in the original.
I went back to the original and had still the same weight.
But when I returned to the copy again, there was a weight difference af some 15%.
When I checked several items, I found out that the weight of the hull had gone to 0, and there must be some other items I have not found yet.
Returning to the original, the same thing had happende there to.
This gives me a very uneasy feeling.
Probably I'm doing something wrong, but when it is that easy.

Is there anyone who has run into this problem?

[lleibman]

Hello Dirk,

We'd certainly be interested to find out what is happening. Is it possible to send us the model (support@orca3d.com)?

Is it possible you made a change to the model after assigning weight/cost properties, for example regenerating a surface or joining/exploding surfaces?

Thanks,

Larry

[Dirk]

Hallo Larry,

I had the time to check a lot of things this weekend, and I think I solved the problem.
I had for some reason copied the hullform on top of the other one, and deleted the one with the info coupled to it. The copy still has the problem, but the original is back to the first weight I calculated.

But I have an other problem.
I made a weight calculation, and put that into the define design condition.
When I choose weight/center and put the weight and LCG, TCG and VCG in, I get a message that there is a sinking feeling.
When I choose float/plane, I get no message, and the weight is close to the calculated one, except that it is negative instead of a possitive.
The model of the hull is made by using the create plate function because I was not able to make a double ended hull using the create hull function.
I'm used to having the hullform with the bow to the right, and for bigger ships, the baseline is the bottom of the ship while x=0 is the centre of the rudderstock.
So, what's wrong? I'll send you my model

[lleibman]

Hello Dirk,

The negative displacement you computed is a general indication that the positive surface normal is not pointing in the expected direction for Orca3D. Orca3D wants the positive normal to point into the fluid. You can use the Rhino Dir command to see the normal direction as well as to flip the normal. I suspect this is the reason for the "sinking feeling" of the model. Let me know if this does not address the issue.

Larry

[Dirk]

Hallo Larry,

Thank you very much, that solved this problem, but I've got a new one. (new program, new things to learn)
Fidling a bit with sinkage in "Float Plane", I found out that the draught for the weight as calculated in Weight and Cost, should be something like 150mm.
When I go to "Weight/Center", and link the weight, LCG, TCG and VCG as given in the Weight and Cost calculation, I get a sinkage of some 48mm.
Is this the extra sinkage because of trim and heel, or do I have to interpret (is this the right word) this in an other way?

[lleibman]

Hello Dirk,

It is important to note that the sinkage is very different from draft. Sinkage is defined as the distance from the origin of your model to the resultant flotation plane. It is sometimes referred to as "origin depth". It is dependent not only on how the vessel ends up floating, but also where the origin was in the model as originally defined, and is very much dependent on trim and to a lesser extent roll.

There is a pretty good writeup explaining the Orca3D orientations in the section, "Heel, Trim, and Sinkage" in the "Hydrostatics & Stability" chapter of the Orca3D help file. Hopefully this clears up any questions related to the reported heel, trim, sinkage.

Thanks,

Larry

[Dirk]

Hallo Larry,

This is what I was looking for. Been looking at the wrong places.
Thanks a lot,

Dirk

[ross]

I really learn a lot in this forum, reading back all the post, my confusions and questions have been answered. Will, its hard reading  all the post but, its worthed. Thanks guys.