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 Post subject: T-foil rudder?
PostPosted: Thu Mar 03, 2011 4:12 pm 
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Joined: Fri Jan 28, 2011 1:40 pm
Posts: 9
From the way i've read the rules, we are allowed to use T-foil rudders.
Has anyone ever tried one?


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 Post subject: Re: T-foil rudder?
PostPosted: Thu Mar 03, 2011 6:33 pm 
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Joined: Tue Jun 02, 2009 8:22 pm
Posts: 98
Yes, John Ellis


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 Post subject: Re: T-foil rudder?
PostPosted: Thu Mar 03, 2011 9:21 pm 
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Joined: Fri Jul 18, 2003 7:53 am
Posts: 142
Location: Emsworth Hants United Kingdom
Yes, Lester Noble.


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 Post subject: Re: T-foil rudder?
PostPosted: Fri Mar 04, 2011 8:06 am 
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Joined: Mon Sep 22, 2003 7:28 pm
Posts: 235
Location: United Kingdom
Andy Paterson tried one on Tin Tear Drop

If you were to try one what would you hope it would do? It seems from people who have tried them, and I have spoken to, that they just add to drag. I think most other classes that have tried them either are a lot shorter or have a lot more sail area. There is actually nothing to stop you putting a foil on the dagger board, but the rule about being able to draw it out through the hull while sailing makes it a difficult one to achieve, and even if you did manage to work around that rule then there is a rule about no holes through the boat except for the dagger board or rudder, and no out riggers, so that means no control wand, (at least that's how I read the rules) I was going to try and work this one out ( I am sure there is a solution within the rules) but realised that it was prob better use of my time getting a new boat together and go sailing!

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Alistair


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 Post subject: Re: T-foil rudder?
PostPosted: Sun Mar 06, 2011 9:26 pm 
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Joined: Sat Oct 10, 2009 8:20 pm
Posts: 24
Location: Leighton Buzzard
Surely one of the main advantages of a T foil rudder is the end plate effect that most classes need to give them more effective rudders, on an IC we already have the end plate at the other end of the rudder so why bother?


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 Post subject: Re: T-foil rudder?
PostPosted: Mon Mar 07, 2011 8:44 am 
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Joined: Mon Sep 12, 2005 7:45 pm
Posts: 766
Location: United Kingdom
>end plate
AIUI the theory behind the things is that its a lot more efficient to lift the boat out of the water and reduce displacement with a 10:1 aspect ratio double sided rudder foil than it is with a 1:10 aspect ratio single sided planing surface.


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 Post subject: Re: T-foil rudder?
PostPosted: Mon Mar 07, 2011 9:51 am 
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Joined: Thu Mar 23, 2006 9:07 pm
Posts: 47
Location: United Kingdom
o jim you havnt learnt yet have you the idea is to keep the b....y thing in the water :lol: :lol: the our tiny rudders work on max efficiency :mrgreen:


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 Post subject: Re: T-foil rudder?
PostPosted: Mon Mar 07, 2011 9:54 am 
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Joined: Thu Mar 23, 2006 9:07 pm
Posts: 47
Location: United Kingdom
sorry forgot to add the major amount of rework unless you have an ellis hull or t :evil: ransom hung rudder to allow you to fit one :twisted: by the way hows your fat a...e affect :lol: ing stickiness :lol: :lol:


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 Post subject: Re: T-foil rudder?
PostPosted: Mon Mar 07, 2011 11:57 am 
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Joined: Mon Sep 12, 2005 7:45 pm
Posts: 766
Location: United Kingdom
bob wrote:
o jim you havnt learnt yet have you the idea is to keep the b....y thing in the water

reduced displacement != boat out of water!
When planing dynamic lift from the hull shape reduced displacement of water and thus wave drag, also to an extent wetted area...
The theory of these foils, AIUI, is that you have a more efficient lifting device having the same effect. Naturally then weight has to be moved back to correct the trim, otherwise it will go bow down.
I think it ought to be possible to make it work, but I'm not at all convinced that its a complication that *I* want to get involved with! It seems possible, even probable that below a certain level of boat speed the extra dynamic lift won't compensate for the extra wetted area, and it seems likely that it would be quite easy to set the foil angle of incidence such that the boat is slower rather than faster.


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 Post subject: Re: T-foil rudder?
PostPosted: Tue Mar 08, 2011 10:51 am 
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Joined: Mon Nov 02, 2009 2:48 pm
Posts: 8
Interesting stuff, I'm a former Mothie from the days of T foil rudders and have sailed a 14 with the large T foil rudder. On the Moth the biggest benefit was that it added pitch inertia to the boat and stopped it hobby horsing upwind. The short Solent chop is just the right wavelength to get an 11' hull pitching and stuffing into each wave upwind. The T foil transformed this motion into gentle bodily rise and fall and made a big speed difference. I snapped my T foil off when launching once and carried on out into the chop, what a huge difference. In addition it almost banished nosedives downwind. On the 14 the foil is large and does a similar thing with the crew moving weight aft to counter the nose down trimming effect going upwind. Downwind in the 14 the kite does most of the bow up trim plus the dynamic lift from the hull of course.
On a canoe being so much longer the pitching effect is not so marked in the chop at Lymington, plus we can't move weight aft so much to balance the trim effect a foil would give. Like all foils it would add drag, which may outweigh any benefit. I'm not trying one either.


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