software to calculate CG

[gonzo]

What is the most user friendly software to calculate Center of gravity and Center of floatation? I am looking for something where it is easy to shift engines or other heavy parts and will recalculate everything.

[CGN]

Excel, there is no "easy way" becouse you need to know each of the weights of each of the parts on the boat so you can get the CG, and once you have this figured, then you can play around moving the heaviest objects like engines to see how you boat reacts.

Maybe something like this:

http://users.isp.com//vsw/pwe-pg1.htm

but you need to have geomtry of your hull and the location of frames and bulkheads

other way to go at it is if is a new design you can "guesstimate" where you want your CG to be, and play around until you are satisfied with the vessel floating condition, but again this is a "guesstimate" you still need to know (or best guesstimate) of the weights of all items and parts of your boat so you can have a fair aproximation to the final weight.

or use some boat for reference so you can "guess" more or less where you can locate your CG

cheers

[gonzo]

I am hoping for something where I could click and drag an object and it would recalculate the waterline. I can do it by hand but is very tedious and easy to make mistakes.

[CGN]

"easiest" thing close to that, maybe bio design

http://www.geocities.com/dumchikov/bio_design/

if you have a hull you can use it to add weights to the hull and see it in free floating condition.

But again you need to know more or less as a preliminary where is your CG, then you can play moving around the main weights (engine, large weights ect..)

[Satan]

You can find Xg coordinate when you know displacement and static moment of the hull.

Xg = Ms/Displacement

Ms is the integral of weight force * coordinate rispect axes of rudder in the range (0 to L.O.A.)
Is easy to find in exel don't worry

[duluthboats]

AC and Excel will interact to some extent, I think maybe Rhino also. Would it be possible to have a 3D model update an Excel spread sheet to accomplish what Gonzo is asking? For the Rhino developers out there this would be a great plug-in.

Gary

[ludesign]

Easy to do in TouchCAD. Just enter a weight or weight per area unit setting for each object in the Object info palette, and do an automatic weight and center of gravity calculation whenever you want. Compare notes with the automatic center of buoyancy. I do this continuously during the design process and requires almost no effort.

www.touchcad.com