Full or fin keel? - Page 84 - SailNet Community
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post #831 of 847 Old 05-21-2013
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Re: Full or fin keel?

Paulo:
I would be extremely surprised if someone working with any of the AC cat teams did not do some CFD. But given the seat of the pants revisions to the designs it appears they should have done more. Because M&M did not do the CFD does not mean that someone else didn't do it.

My comment about M&M was made because Jody Culbertson who does my 3D rendering work has also been working with M&M on a cat project (not AC). We discused this today, this morning. He asked M&M about doing some CFD work on another project he was involved in and Gino told him they did not use it. They use VPP's. This is not first hand information. But it is second hand. I did not read it on the internet.

The horse is really still now. Doesn't look good. Probably playing possum.

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post #832 of 847 Old 05-21-2013
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Re: Full or fin keel?

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Originally Posted by bobperry View Post
My comment about M&M was made because Jody Culbertson who does my 3D rendering work has also been working with M&M on a cat project (not AC). We discused this today, this morning. He asked M&M about doing some CFD work on another project he was involved in and Gino told him they did not use it. They use VPP's. This is not first hand information. But it is second hand. I did not read it on the internet.

The horse is really still now. Doesn't look good. Probably playing possum.
Bob, I was not doubting. M&M have a specialist in VPP in their design team but then VPP is strongly based on CFD. They are very complex program with its roots in it. Some work directly with CFD, some use programs that are based on. Both are very powerful computer analytic tools that can predict how a boat will behave and can help boat design. On AC teams they have both, CFD and VPP specialists.

Regards

Paulo


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post #833 of 847 Old 05-21-2013
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Re: Full or fin keel?

Paulo:
Thank you for educating me. If you had been around 35 years ago I might have made a name for myself in this business.

I herebye declare this horse well and truly dead.

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post #834 of 847 Old 05-21-2013
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Re: Full or fin keel?

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Originally Posted by bobperry View Post
Paulo:
Thank you for educating me. If you had been around 35 years ago I might have made a name for myself in this business.

I herebye declare this horse well and truly dead.


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post #835 of 847 Old 05-21-2013
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Re: Full or fin keel?

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Originally Posted by bobperry View Post
Paulo:
Thank you for educating me. If you had been around 35 years ago I might have made a name for myself in this business.

I herebye declare this horse well and truly dead.
Bob, I don't know why you find everything I say offensive I was just trying to say this regarding the correlation between the more advanced VPP computer programs and CFD:

"CFD programs do not calculate how fast a boat of any type will pass through the water or predict the time to complete a course around the buoys. Predicting speed on a racecourse is the domain of another class of programs called Velocity Prediction Programs or VPP. The VPP makes use of
lift and drag numbers calculated in a CFD program to estimate the speed about will sail a course given the sail drive forces and the stability or righting moment of the hull
.

The VPP is a closed loop simulation continuously varies estimated speed and resulting lift, drag and righting forces until retarding and driving forces are balanced and a stable speed results. A CFD program on the other
hand is an open loop simulation that simply states that given an angle of heel and speed for a specified hull and appendage configuration, here are the forces that will result for that instant in time. No consideration is given to how the vessel achieved that speed or sailing condition."


http://www.vacantisw.com/articles/co...20dynamics.pdf

I am quite sure you know the relation of a powerful VPP program with a CFD program and know that M&M use advanced computer simulations to develop their hulls but this is a Forum and most here don't know how an advanced VPP works or its relation with a CFD. I like to share the little knowledge I have and contribute to a more informed forum.

Regards

Paulo


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post #836 of 847 Old 05-21-2013
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Re: Full or fin keel?

paulo with all due respect the problem is you are not. many here work with computers daily either doing cad/cam,economic predictions,hard science or medical science. we are aware of various types of multivarient analysis, basic and complex statistics,vecter analysis, engineering design and the various purposes computing can be put to. however, we are less informed as to why we get on some boats and they sail well, we are comfortable, everything is in the right place and we feel confident in all weathers and get on other boats and at some organic level it's just not right. Jeff and Bob have been teaching us why some things work and some don't. all boats are compromises. I been learning why I made the choices I have. I know what I want in a blue water vessel but I don't know why on a detailed level. it is self evident anyone in the competitive environment of yacht design will make use of what tools they can to produce the design their client desires. they have been the guides to understanding our desires and how they try to meet them . you have not. please allow the discussion to move on.

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post #837 of 847 Old 05-22-2013
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Re: Full or fin keel?

outbound, you hit it. did that with a block wall I had to build for aclient once. I could see generally how to design it, BUT, I had a feeling it was not quite right. Talked to some one, he cranked a few numbers, said do it this way, even tho the design specs said do it that way! Glad I did it this way, as a 5 something quake hit a yr or so later. While I will not say the wall would not have held as the spec said, the way it was built, it did hold up with more wt behind than initially though!

Like all things, there is more than one way to skin a cat! or dog, or catfish or __________!

If someone can get a full keel to plane at 2x the hull speed of a boat, I'll buy one, if not, I'll take the fin thank you very much!

marty

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I drives me dinghy!
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post #838 of 847 Old 05-22-2013
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Re: Full or fin keel?

The moderators have moved two off topic post to Holding for further review.


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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
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Re: Full or fin keel?

Jeff, I don't see the thread in the off topic forum. I think it's a shame to move it there over a few differences of opinion, especially when it's one of the more informative threads going right now on SN. Unless I missed something, it's been pretty civil so far.

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Re: Full or fin keel?

It is not being moved to "Off-Topic". Two posts were moved to a thread that only the moderators can see. We were asked to disclose when we moved things out of sight. That is why the bread crumbs were left.


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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
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