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Go Back   SailNet Community > General Interest Forums > Boat Review and Purchase Forum > Sailboat Design and Construction
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Old 09-19-2012
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Moment curves

I came across this amongst the pile of plans.. Can anyone tell me exactly what it's trying to tell me?



Thanks,
Cameron
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Old 09-20-2012
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Re: Moment curves

whoa ... did all the pans come with her C ? That is wonderful.

Now as for me I have no idea what that actually means but how about the wave created by the boat at the nominated angles of heel at max hull speed ?
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Old 09-20-2012
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Re: Moment curves

but I think I'd be totally wrong ....



though that illuminates my poor dim mind not one iota.
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Old 09-20-2012
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Re: Moment curves

Try this ....

Understanding monohull sailboat stability curves | M.B. MARSH DESIGN

Seemingly absolutely nothing to do with wave motion and all to do with stability.

May I go back and remove my first post please ?
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Old 09-20-2012
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Re: Moment curves

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Originally Posted by tdw View Post
.....though that illuminates my poor dim mind not one iota.
I looked at that link... that must make us 'dim' and 'dimmer'.....
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Old 09-20-2012
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Re: Moment curves

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Originally Posted by Faster View Post
I looked at that link... that must make us 'dim' and 'dimmer'.....
Add me and we have "dimmest". Unless it's Steven Hawking speaking I can usually grasp the concept but that link was totally ununderstandable.
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Old 09-20-2012
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Re: Moment curves

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Originally Posted by tdw View Post
whoa ... did all the pans come with her C ? That is wonderful.
..and not just the plans but the specification also!! - including the following statement which explains why it's all so rare.

Do Jeff and Bob write stuff like this? I'd be curious to know:

Moment curves-untitled.jpg

That the original owner ignored that statement and that the previous owner was an architect (and document hoarder!) is one of the reasons the ANMM catalogued her.
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Last edited by Classic30; 09-20-2012 at 03:26 AM.
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Re: Moment curves

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Originally Posted by SloopJonB View Post
Add me and we have "dimmest". Unless it's Steven Hawking speaking I can usually grasp the concept but that link was totally ununderstandable.
At least now I know I'm not the only one!

From Wikipedia: "The convex hull of any finite set of points on the moment curve is a cyclic polytope.[3] Cyclic polytopes have the largest possible number of faces for a given number of vertices, and in dimensions four or more have the property that their edges form a complete graph. More strongly, they are neighborly polytopes, meaning that each set of at most d/2 vertices of the polytope forms one of its faces. Sets of points on the moment curve also realize the maximum possible number of simplices, among all possible Delaunay triangulations of sets of n points in d dimensions.[4]"

Repeat that quickly at your next dinner party and your 'neighbourly polytopes' will tie you up in white canvas and pack you off to the local looney bin!!


(..so I'm secretly hoping one of the Design Gurus around here can teach us something before we all go barmy. )
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Last edited by Classic30; 09-20-2012 at 03:28 AM.
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Old 09-20-2012
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Re: Moment curves

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Originally Posted by Hartley18 View Post
I came across this amongst the pile of plans.. Can anyone tell me exactly what it's trying to tell me?

Thanks,
Cameron
I believe that is a graphic of the moments of the immersed area taken about a longitudinal axis of the hull at the indicated heeling angles.
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Old 09-20-2012
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Re: Moment curves

Those are very interesting curves but they don't tell me anything. I just need a more simple explanation other than the Wiki one. I would think a more useful set of curves would be immersed volumes at various heel angles. For my simple approach to design that would be a more tangeable way to look at immersed heeled volumes. I've been around the world of yacht design professionaly now for 45 years and I have never seen them before. Maybe Jeff can explain them. Now I really want to know.
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