# 1.618

Discussion in 'Boat Design' started by Fanie, Mar 29, 2014.

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### FanieFanie

Hi guys,

This is a weird question. The number 1.618 seems to have some significance in the ratio of things, you can google it and see what comes up.

I was wondering if this has any bearing (or advantage) in boats, multihuls, sail ratio's, and more... perhaps... ?

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Well, if you designed a catamaran and wind up with 1.618 hulls you know you're in big trouble......

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### FanieFanie

Hello Doug,

Yes you would be but that is actually a ratio.

1.618 x 5 would give you 8m... and you'd be in a lot less trouble, right ?

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There must be a mistake somewhere: 5' X 1.618= 8.09' , right?
Sorry, I guess I'm in a silly mood......

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### FanieFanie

There is a mistake, you should take your feet out of it !

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### PARYacht Designer/Builder

This is an old and convoluted bit of fascination in western societies. About 2,500 years ago the Greeks explored mathematics and Euclid (I think) was a proponent of this particular "golden ratio" believing it was an aesthetic and mathematical guide, particularly in geometry. This "golden section" mentality drove a lot of the design in it's day, for example you'd find window opening heights, 1.6 times their width, or in calculating a pentagon. More recently artists have run with it, such as Dali and Leonardo da Vinci. It wasn't until the early 19th century that the various terms received wide spread acceptance.

On a technical level you can get pretty involved with inverse golden ratio, Fibonacci sequence, Odom's construction and geometry. The great Pyramid of Giza is quite close to the golden rule. The Parthenon is suggested to involve it, as are countless other works of art, buildings and even analyses of the stock market (some will just buy into anything). It's a reasonably well documented ratio - though simpler to just remember (line segments): "A+B is to A as A is to B"
or . . .

. . . which makes it reasonable to conclude:

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### RurudyneSenior Member

The Fibonacci series (1-2-3-5-8-13-21-34-55-etc) is approximated by this number and it appears in nature everywhere and is appealing in art and aesthetics. When styling a boat, say its topsides, to the extent you can keep it mind it may help to come up with attractive proportions. Thankfully you don't have to keep exactly to the average even when using the concept, there are times 2:1 looks best, times 8:5 looks best, etc, and it's up to you which for any particular proportion of parts.

But it is no theory of everything. It may help to get a roofline attractively high relative to length or beam or whatever (again, your choice) but I've yet to read anything that says strictly adhering to it will make your hull better.

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### FanieFanie

What's with the hieroglyphics in the post, Par...

I understand the number series etc, if I'm not mistaken then in grade 1 IQ test they had one complete the number lines and that was one of them. You completed the IQ test to see if you are intelligent (yawn...) enough to play with clay and other blunt objects like 9mm ammo as to 308 ammo that was a lot sharper. Well everyone had guns back then, no one got hurt or killed. I guess the low IQ kids got their's stuck up the nose or in the ear and most likely elsewhere as well, and these were probably destined to become politicians since they fcuk everything else up as well, so don't vote. I failed grade 1 though... well I broke a finger and couldn't do the clay exam, had to redo the darn test.

Is there any relation to say a cat's LWL and the beam that represents this 1.618 or come close to it... for drag reduction perhaps ? The height of a sail as to the boom length for better performance... stuff like that. I know it's not being used, I was just wondering about the number ratio. Daggerboard diameter of 1 and the rudder at 0.6... ? The daggerboard at 1 of the 1.6 from the stern maybe ?

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### FanieFanie

Now what ? !

Apparently there was a time in history a lot of people considered this ratio in most things they did, as did the earlier day freemasons who believed it gave them more energy (for some reason).

Anyway, since this ratio exist, there may well be a bit more to it than just a number that comes up. In the previous post I asked if there was some usefulness regarding mutihulls....

and the forum crowd disappeared...

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### PARYacht Designer/Builder

I don't know of any uses in multihulls, though I'm sure someone has incorporated this ratio, in one of it's various forms at some point, begging the question why, but . . .

It's a handy thing in some geometry operations, but in most cases, particularly since the advent of computers, entirely unnecessary. From the aesthetic point of view, it's been loosely held, though most artists are just anal or weird enough (ever know a real artist) to arbitrarily use whatever they think looks right, rather then adhering to a fixed formula. As a rule right brained folks will have difficulty with something like this, while left brained will find some comfort in it.

I'm not sure of you impatience on this topic Fanie, but lots of things have gained favor and widespread use, just to fall away once better understanding came along. The Cod's Head designs where thought to be the bee's knees for a long time, but didn't work out as envisioned or postulated. The world was once accepted as flat. Selling your daughter for a fair value, stoning your neighboring farmer, for growing different crops in adjoining fields to yours, slavery, the idea that man didn't have wings so was limited to ground bound life, that you couldn't sail current over wind speed, that cats can't point and that 12 meters where fast; all have enjoyed ridiculous commentary, by supposedly informed and enlightened, just to have reality or social advancement hand it to them.

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### frank smithSenior Member

PAR, Not to sure how arbitrary what looks right is. There may be more to it than that , but you would have to ask an artist.

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### FanieFanie

I was hoping this would have a more technical turnout and not a socialistic one.

There was a discussion even on shark skin boats, not sure how the skin turbulated itself into more speed, but since there may well be a relation between a lot of things, one of these may well gain you a bit of advantage, perhaps the swell height vs boat length bla bla bla.

If however there is none to say about this, then we will all be on our way again

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### hoytedowCarbon Based Life Form

Sharkskin sounds good but makes it hard to slide boat off trailer carpeted bunks.

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### RurudyneSenior Member

Be an interesting SoF application if someone literally went there (or just figuratively with that swimsuit material).

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### FanieFanie

Yes, but that's because the shark skin is at the 1.618 ratio

You mean wearing it ! The picture is of a leopard that swallowed a beeeg person, just so you know what it could look like.

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