Cof/CoG

[gonzo]

I have asked in the past without success about some software that can easily change loads in a design. Something where you could click on say, the engine or a tank, drag it and it would calculate how the vessel floats.

[Ad Hoc]

That is the job of the naval architect, because this is a multidisciplinary design.

Changing the tank location..is there room for it...software wont tell you that...is there sufficient volume available, software can tell you that, but wont tell you if it is easily accessible, nor if it complies with Class/Flag rules...the software you draw this new location in, is just that, drawing software. It may provide, if set up correctly the new LCG, but that also requires input to the software to begin with. Then this new LCG must be taken into a hydrostatic software, which is different again. This software is not linked with any drawing or LCG/Mass software.

All these softwares are stand alone. It requires even the user to plug data into one software then extract "the result" from that one and import "this" data into another to obtain the result.

If you don't know what you're doing, it ends up the usual GIGO.

That is why one uses a naval architect for proper results and analysis of implications of moving things about and not put ones faith into ostensibly a data input person.

[gonzo]

Ad hoc: If you can't answer my question, please stay off this thread. I don't need your bad attitude. The question is simple.

[Ad Hoc]

Gonzo

Thanks for the childish immature neg reps.

the question has been answered. If you fail to understand this, that is your problem, not mine, and just demonstrates that the task you wish to perform is beyond your ability.

[lewisboats]

You can create various blocks and assign them weights in Freeship...export them as .part (s) and then import them into your designs. Move them around and you can see where the cog will be in the data at the bottom of the design hydrostatics page, which you can then compare to the various other data to get your moments. Once that is achieved you can rotate the model and reposition the waterline to balance things up and it will show you your resting attitude for that particular combination. It is a bit of effort but it does work.

[MikeJohns]

Originally Posted by gonzo

I have asked in the past without success about some software that can easily change loads in a design. Something where you could click on say, the engine or a tank, drag it and it would calculate how the vessel floats.

That's what we really do all the time, you assign a new location in the weights and moments entry for that item and calculate your trim, heel, GM KG etc accordingly. As noted the easiest way is to put the new LCG into the hydrostatics package. Calculating the result on the fly dynamically as you drag the item is beyond a PC's capability unless the data is already extant.

[gonzo]

I was looking for software that does in on the fly. For small designs I can do it on paper faster than I can do it with software. Maybe I'll go ahead and write software that does it on the fly. What interest may there be for it?

[jiggerpro]

Hi, Gonzo,

I have a partial solution for you, that you might find better than waht you was looking for but it involves some basic math related to the calculation of the CG of an object so it is not as straight input as you want it to be but the final result I find very interesting.

You calculate the longitudinal position of your center of gravity, assigning weights and distances to the origin of coordinates wich of course you can alter by changing the distance of every heavy item for example the tank.


When you input the position of this calculated position of the CG into Orca 3d which is a plug in for Rhinoceros the Orca software will draw for you taking into account the geometry of the hull the position of the water line level.

Sorry if I have not expressed myself clear enough if you did not understand my not so good english I can try again being more elaborate please let me know and feel free to PM me.

This I find very interesting as it works as a floating simulator allowing you to (trough some trial en error) position your main weights accurately and see the result as the floating vessel.

I only have one example to show you, which I did to see how my hull would float with 6 (75 kg each ) persons in one of the stern corners.

The program takes into account the buoyancy of the designed geometry and the position of the center of gravity.

Rhinoceros also can calculate for you an estimation ( based on skin specific weight ) of the position of the CG of the hull itself.

I did all this some time ago and now Orca 3D has changed version and I have not used it since then but roughly what I explained is what I did.

Not really sure if I have been of any help

[gonzo]

Yes, I think I follow. Thanks

[ontwerp]

Hey gonzo, i often do what you are describing, using napa. It has a loadcase editor where you can shift weights around and see the resulting floating position, bending moments, and results of stability in real time.

Hope that is of some help...

[gonzo]

I have never used napa. I will look into it.

[Humberto]

Hi Gonzo,

This is a part of he design process I tried to optimise in my jSDN software. You can assign a weigth or density to any NURBS volume or surface, and the program automatically computes its CoG, it is shown on the design windows, and when you move a volume/surface, both global CoG and moments of inertia are automatically recomputed. The trim is also computed, but drawings are not modified.

You are free to use it. And I can provide information on how to use such features.

Humberto

[gonzo]

Thanks. I'm on vacation until next week. When I get back home my brain will be ready to take on the challenge. I will be in touch with you. From the responses in the past, it seemed like no one had anything.

[quequen]

Originally Posted by gonzo

For small designs I can do it on paper faster than I can do it with software. Maybe I'll go ahead and write software that does it on the fly. What interest may there be for it?

Gonzo, can you post here a short explanation about your paper calc metod? Is it a graphic metod?
I guess many people has interest on the software you try to do, please keep us informed!
Humberto, I emailed you a few questions to jsdn-info@ingeniatecno.com , no answers yet, is this e-mail valid?

Thanks

[Humberto]

Originally Posted by quequen

Humberto, I emailed you a few questions to jsdn-info@ingeniatecno.com , no answers yet, is this e-mail valid?

Thanks

Back to work. I have been sailing (very good racing indeed). And I am now answering emails.