Of course next weekend is the final test but it is clearly seen here what the problem was!
https://www.facebook.com/…otif_t=video_wall_create
https://www.facebook.com/…e=2&theater¬if_t=like
i might pick up 2 knots, and able to fly a hull easier...
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Here is the Transom fix Of my Reynolds 21!
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Posted: Apr 20, 2014 - 08:10 PM
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Posted: Apr 21, 2014 - 11:14 AM
I can't get to the items linked in Facebook. :(
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Sheet In!
Bob
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Prindle 18-2 #244 "Wakizashi"
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Posted: Apr 21, 2014 - 02:02 PM
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Posted: Apr 21, 2014 - 07:10 PM
Sorry about this i have to recreate this video
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Apr 22, 2014 - 08:20 AM
http://magis.to/Ins6TFlaRF0tPSkHDmEwCXt9
Here you go i hope it works that link!
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Apr 23, 2014 - 01:00 PM
Putting the boat into lake this Saturday. . Test time
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Apr 23, 2014 - 02:00 PM
I can't really tell what the problem was or what you did to fix it?
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Damon Linkous
1992 Hobie 18
Memphis, TN
How To Create Your Signature
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Posted: Apr 23, 2014 - 05:13 PM
IIRC from last year, he had weather helm, big time. It appears the "plug" added to the transom angled the top of the rudders aft, & moved the tips forward, more under the boat.
I hope he designed it to be adjustable, or gets lucky, otherwise it might end up with lee helm.
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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
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Posted: Apr 23, 2014 - 08:07 PM
we built a box, see the black box on the transom! that is what i added it makes the rudder straighter, if you see the one video the rudder is like angled once you turn the rudder it made it very hard to steer at higher speeds. i also had Lee Helm the boat would fall off to add to the steering problem so now i hope this MOD will fix my problems.. if you look at all transoms that have rudders on the stern they all are straight and not at a angle.
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Apr 23, 2014 - 10:57 PM
aft raked cat rudders and daggers were a bit of a design fashion in the 70s+80s
think tornado centreboards, hobie and nacra rudders
i think they thought they would have less drag that way?
the raked rudders gave a horrible helm but maybe it was thought the price for the speed
but slowly all the foils went vertical and as the sky didn't fall
older boats have been slowly mod'ed to catch up
in nz the old gbe cats like this
http://www.boatdesign.net/forums/attachments/multihulls/68623d1332285419-historical-multihulls-gbe.jpg
have now been mod'ed like this
http://assets.cougar.nineentertainment.com.au/imagegen/p/black/1024/768/assets/momoads/2013/01/22/17/great_barrier_express_(gbe)_for_sale.jpg -
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Posted: Apr 24, 2014 - 06:22 AM
I think there are two phenomena to distinguish: Weather or lee helm and helm resistance.
Whether or lee helm is about where the boat wants to go by itself, without steering. It depends on mast rake mainly (think about windsurfing).
Helm resistance is about the forces caused by water on the rudder when you steer. This is what is being addressed here and it depends on how far is the rudder surface relative to the axis of rotation (rudder pin). In simple terms (I'm sure there are more complex physics..) the surface aft of the axis produce forces against the steering efforts and the surface forward will help steering.
So the mod done by soulofasailor will certainly help with helm resistance and should not produce lee helm (or if it produces some, just adjust mast rake), because there is no rudder surface forward of the rudder pin, as seen on the video. That also means that there's still room for improvement, by changing the rudders shape (same shape displaced forward) or raking beyond the vertical. -
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Posted: Apr 24, 2014 - 07:26 AM
We will know if this worked . But I have already did and tried taking of mast .. and tightening of the stays nothing helped Iif you watch the first video you will see the angle of the rudder doesn't look correct . What also was wrong was the toe in all of this is much better now so I can'twait to fly this mug! :) stay tuned
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Apr 24, 2014 - 08:29 AM
Yes, we are saying the same, the mast rake wouldn't help with the helm resistance that you had, because it was caused by the angle of your rudders.
The mast rake may bias the boat to turn towards one side or the other, but the helm resistance acctually happens when turning to either side, so you would feel it anyway, whether to steer or to fight against an unbalanced helm. -
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Posted: Apr 24, 2014 - 08:56 AM
Here is how you could further decrease the helm resistance (or rudder moment)
Explained here, scroll down until you see the picture above.
http://www.catsail.com/archives/v2-i8/feature1.htm -
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Posted: Apr 24, 2014 - 12:47 PM
For anyone following this topic or finds it when searching here is an old article that does a great job of explaining the forces that cause weather or lee helm.
What's All This About Weather Helm.
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Damon Linkous
1992 Hobie 18
Memphis, TN
How To Create Your Signature
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Posted: Apr 29, 2014 - 02:05 PM
What a difference i can set the boat and leave the tiller now! Awesome Stuff!
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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