Rudder shape ?

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trebor
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Rudder shape ?

Post by trebor »

What is considered the best shape for a Rudder blade ?

The Rudder blade on Sprint, which I assume is same for all Minisails, the leading edge is angled back from vertical, quite a bit actually, I have altered angle of mine so it is almost vertical.
Class legal issues do not apply, I will make blade "shape" and length width etc considered most efficient.
Robert
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Nigel
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Re: Rudder shape ?

Post by Nigel »

don't know the answer but I did think this looked rather exotic -

http://www.ebay.co.uk/itm/Fixed-rudder- ... 3aaf461c7e
JimC
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Re: Rudder shape ?

Post by JimC »

The current fashion seems to be vaguely like that but with the tip under the centre of the board so that there's a reverse curve in the trailing edge.
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trebor
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Re: Rudder shape ?

Post by trebor »

Nigel, could be useful for dealing with fishermen.

I am sure I read somewhere the Rudder blade should be no more than 2 thirds of centre/dagger board ?
Robert
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Rupert
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Re: Rudder shape ?

Post by Rupert »

On a boat like the MS, a simple rectangle will be fine, and far easier to make a nice cross section, which is where the current rudder is very poor.
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roger
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Re: Rudder shape ?

Post by roger »

Hornet 191 Shoestring,
Hornet 595 Demon awaiting restoration
Hornet 610 Final Fling
Hornet 353
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trebor
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Re: Rudder shape ?

Post by trebor »

Wow, figures look impressive.
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Re: Rudder shape ?

Post by GAv »

My Wooden Sprite rudder fits the pintails on the Monaco Minisprint hull, but I can't remember what the rudder tiller was like when I had a Minisprint 11 but would make an uneducated guess that they are the same. :x
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Re: Rudder shape ?

Post by Nigel »

trebor wrote:Wow, figures look impressive.

but..... they seem to be quoting research on the fin "tubercules" (i.e the whale fin) rather than testing the "Turbocle" rudder's performance directly

I cannot see why increasing the surface area would reduce straight ahead drag but someone with your skills should be able to knock up a blade easily enough and do some testing - that is the only way to find out really
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Re: Rudder shape ?

Post by JimC »

trebor wrote:Wow, figures look impressive.
If you look more closely I'm not entirely convinced that all the things they quote translate into advantages on the race course. For instance being able to put the rudder over harder before it stalls may actually be slower rather than faster because of all the extra drag from the rest of the hull if you turn too fast. We already know that in most circumstances people over use rather than under use the rudder.
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trebor
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Re: Rudder shape ?

Post by trebor »

The only independent discussion was on the y and y forum In 2012, the consensus was, needed more testing, manufacturer claims narrower blade achieved with this design, due to reduced cavitation
Last edited by trebor on Tue Aug 11, 2015 5:59 pm, edited 1 time in total.
Robert
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Re: Rudder shape ?

Post by roger »

There is one I know of being used on a Hornet, probably not a large enough sample to be useful but they were positive about it. They probably would have to be as they own 50degree sailing.
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trebor
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Re: Rudder shape ?

Post by trebor »

The basis of this design, is taken from nature, the humpbacked whales fins are substantially narrower than other marine creatures of comparable size (Dolphin, Shark etc).

I wonder how many they have sold ?
The designs been out there for a long time now, are their any newly designed dinghies using it?
I know a lot of classes would not be able to use this rudder shape, but their are plenty of classes with out restrictions.
One of the contributors on y&y forum said this would be ineffective below 5 knots and would probably be slower, also ineffective above 30 knots, thats me out then :D
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trebor
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Re: Rudder shape ?

Post by trebor »

I am going to try Tubercules, combined with a Chord.

I hope I will not be breaching someones patent ?
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Re: Rudder shape ?

Post by realnutter »

trebor wrote:I am going to try Tubercules, combined with a Chord.

I hope I will not be breaching someones patent ?
Don't think Mother Nature takes out patents....
Matt

Int Moth K2992
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