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  #16  
Old 10-06-2010, 01:09 AM
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Martijn_vE Martijn_vE is offline
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Quote:
Originally Posted by MikeJohns View Post
Just make sure the package is free to trim. Archimedes wasn't the last time I looked at it .

Is freeship?
No, it's not (at least up to version 2.6) which makes it next to useless especially for small boats.
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  #17  
Old 04-17-2013, 02:56 AM
smp smp is offline
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Combining Rhino and MAAT Hydro may be a solution:

http://www.sistre-shipdesign-softwar...on/#maat-hydro
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  #18  
Old 04-17-2013, 03:39 AM
J Feenstra J Feenstra is offline
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Don't you need the Orca plug in for extracting the GHS markers?
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  #19  
Old 04-17-2013, 03:48 AM
smp smp is offline
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MAAT Hydro just operates directly on Rhino's IGES exports and doesn't need any plugin. It provides free real-time hydrostatic analysis, basic stability calculations, etc...
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  #20  
Old 04-24-2013, 12:31 AM
quequen quequen is offline
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For simple "on the fly" hydrostatics and Stability Curve, including Trim Angle, GZ, Cp, SWA, Area Curves, Tc, T, etc. you can try PolyCAD. It's free. Check this links:

PolyCAD tutorial: Hydrostatics for Delftship, Freeship, Rhino files

PolyCAD tutorial: Hydrostatics for Delftship, Freeship, Rhino files
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  #21  
Old 11-23-2016, 03:33 AM
terrnz terrnz is offline
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I have a problem with FreeShip stability calculation of soft curves in that although there is a an input field for center of gravity (VCG) it seems to have no effect on the cross curve values. I am working with yacht designs and clearly a deep keel and bulb ( resulting in a negative VCG) should have a significant effect on righting moment.
The KNsin data is equivalent to GZ ?
Is the KNsin data only form stability ?
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  #22  
Old 12-20-2016, 06:45 AM
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jonathan jonathan is offline
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Quote:
Originally Posted by terrnz View Post
The KNsin data is equivalent to GZ ?
Is the KNsin data only form stability ?
KNsin(Ф) is only form stability, yes, but it is fairly easy to compute the actual GZ from it. Just add or substract the horizontal distance from the center of gravity to the keel, and that will get you the GZ.

The actual formula would be GZ = KN*sin(Ф) - KG*sin(Ф)

If your center of gravity is not on the centerline, do not forget to take it into account.

Hope that helps.
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  #23  
Old 12-22-2016, 02:04 AM
terrnz terrnz is offline
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stability

Ok formula which have the I have worked with. My question is: taking the measurements from the lowest point of the hull as base line which is how FreeShip and Delft work with a light displacement sailboat and a bulb keel you have a negative CG . it makes sense to me mathematically and empirically and seems to give a credible figure.
Should VCG be taken from the base line or VCB?
changing the baseline to the lowest point of the keel/bulb so all figures are positive gives an unrealistic value. I am probably doing something wrong
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  #24  
Old 12-22-2016, 02:09 AM
terrnz terrnz is offline
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Quote:
Originally Posted by Martijn_vE View Post
No, it's not (at least up to version 2.6) which makes it next to useless especially for small boats.

what do you define as a small boat LOA?
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  #25  
Old 12-22-2016, 05:02 AM
TANSL TANSL is online now
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Quote:
Originally Posted by terrnz View Post
Should VCG be taken from the base line?
Of course.
Choose a baseline, whatever you want, and take all measures regarding that B.L.
Before you start calculating things, it would be convenient to review your concepts about ship theory. Ask your questions here, as simple as they may seem, and we'll give you some answers, but you must provide some basic knowledge.
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