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Author Topic: Rudder Relationship  (Read 3283 times)

bj

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Rudder Relationship
« on: December 11, 2014, 08:17:34 pm »

Looking at the attached sketch, if the prop is positioned at 8 to 10% of the boat overall length then where should the BACK EDGE of a rudder be in relationship to the transom?
Should it be almost the same 8 to 10% figure?



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martno1fan

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Re: Rudder Relationship
« Reply #1 on: December 15, 2014, 11:19:41 am »

I always prefer to have the rudders leading edge either behind or at least level with the trailing edge of the prop.
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Den W

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Re: Rudder Relationship
« Reply #2 on: December 15, 2014, 10:08:17 pm »

To the right  or directly behind the prop
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martno1fan

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Re: Rudder Relationship
« Reply #3 on: December 16, 2014, 06:53:43 pm »

Heres a pic showing the rudder offset to the right ,which is what most seem to use,its in line with the engine stringer.
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Den W

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Re: Rudder Relationship
« Reply #4 on: December 16, 2014, 07:25:38 pm »

Thanks for the photo, whats your take on the rudder being directly in line with prop
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bj

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Re: Rudder Relationship
« Reply #5 on: December 17, 2014, 08:00:19 am »

...... showing the rudder offset to the right ,which is what most seem to use.




 ...... which is OK for the clockwise BMPRS & OMRA circuits but my club races a clockwise M course so turn 3 is a LEFT HAND TURN which really dictates an in line configuration or TWO rudders (one each side of the drive).
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martno1fan

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Re: Rudder Relationship
« Reply #6 on: December 17, 2014, 03:19:44 pm »

Ive never had too many issues turning left with this setup,yes turns are maybe not as sharp but not that youd notice once the boats trimmed in etc.Rudder needs very little throw once boats at full tilt anyway,for a left turn just use a tad more left stick is all ive ever needed to do.I dont like the rudder behind the prop on a surface drive but i know some have tried it.
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w3bby

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Re: Rudder Relationship
« Reply #7 on: December 18, 2014, 03:04:33 pm »

Swedish offshore often race M-course clockwise and their boats manage perfectly well with the right offset rudder....

martno1fan

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Re: Rudder Relationship
« Reply #8 on: December 18, 2014, 10:20:17 pm »

Yes i think a few others do too Ian  :-))
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