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Tell me about T foil rudders. |
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Daniel Holman
Really should get out more Joined: 17 Nov 08 Online Status: Offline Posts: 997 |
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Quote Reply
Topic: Tell me about T foil rudders. Posted: 13 Feb 18 at 2:57pm |
Graeme,
First rule of tfoils, you don’t talk about tfoils. Second rule of tfoils, it’s always much, much cheaper and easier to achieve a similar end by making your boat a foot longer :-) Fab. Ha aha ah |
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Sam.Spoons
Really should get out more Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3398 |
Post Options Quote Reply Posted: 13 Feb 18 at 3:06pm |
What about t-foils and rudder gantries combined then, can we talk about those.......
Edited by Sam.Spoons - 13 Feb 18 at 3:07pm |
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Spice 346 "Flat Broke"
Blaze 671 "supersonic soap dish" |
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Jack Sparrow
Really should get out more Joined: 08 Feb 05 Location: United Kingdom Online Status: Offline Posts: 2965 |
Post Options Quote Reply Posted: 13 Feb 18 at 3:27pm |
Basically - Energy recovery. You are effectively surfing your own stern wave as well as reducing the weight of the crew / crew displacement by placing your weight over the foil.
BTW... to the forumite - thanks for the YouTube link. Shame the YouTube bar stewards have stopped paying advertising revenue for YouTubers with under 100k views!
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Daniel Holman
Really should get out more Joined: 17 Nov 08 Online Status: Offline Posts: 997 |
Post Options Quote Reply Posted: 13 Feb 18 at 4:07pm |
Pressure recovery is a very minor part of the gain, applicable to heavily rockered hulls at lower speeds.
It’s all about getting displacement out of the hull (typical dinghy resistance to weight ratio 1:10 at 10 kts) and onto the foil (l/d ratio ~ 30:1) at semi displacement speeds (so 6-12kts for dinghies) Above that speed generally the bow down moment of the rig means you can’t run the foil in positive so it’s just wasted area. Some pitch damping though. At high speeds or when beating Away, running in negative keeps the bow up on short boats with big rigs downwind, meaning you don’t compromise the hull design the rest of the time to make it surviveable in bear aways and hairy downwind stuff. |
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turnturtle
Really should get out more Joined: 05 Dec 14 Online Status: Offline Posts: 2538 |
Post Options Quote Reply Posted: 13 Feb 18 at 4:35pm |
It’s good to know that with all these customisations the new boat will be so FARR out of class, that even you will accept there is no conspiracy around your own personal handicap...
Back to dinghy development, not PYAG bashing... hurrah! Edited by turnturtle - 13 Feb 18 at 4:35pm |
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Jack Sparrow
Really should get out more Joined: 08 Feb 05 Location: United Kingdom Online Status: Offline Posts: 2965 |
Post Options Quote Reply Posted: 13 Feb 18 at 4:59pm |
I thought my post would drag you out of your tower. Now iGRF doesn't need to come to your stand. LOL.
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iGRF
Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496 |
Post Options Quote Reply Posted: 13 Feb 18 at 6:12pm |
Energy recovery I don't buy, nor can I see them doing much about keeping the nose up, but pitching dampening I can see, so could keeping the nose down on upwind legs into the sea. I also think the additional length offwind in marginal planing could help, especially if mounted back a bit on a gantry, but I'm not sure how class regs would view that.
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Jack Sparrow
Really should get out more Joined: 08 Feb 05 Location: United Kingdom Online Status: Offline Posts: 2965 |
Post Options Quote Reply Posted: 13 Feb 18 at 6:34pm |
It's fine in the class rules iGRF. But getting the right section / size for the foil will take some maths / experimentation. As will the adjustment system. Although Moths / N12's have done most of that work for you.
Yes there is energy recovery. Yes there is reduced displacement. Yes there is pitch dampening. It depends which way you pull the strings. FYI... I was in N12's when this idea was first conceived. Conceived by an incredibly bright but back of the fleet sailor. Who's name escapes me. Who was widely ridiculed at the time by top of the fleeter's for his badly built experimentally rudder stock and therefor it's lack of ability to show it's performance gains.
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iGRF
Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496 |
Post Options Quote Reply Posted: 13 Feb 18 at 7:10pm |
Eh? Did I read that right? Have I died and gone to heaven? Bring it on, I can't wait.. |
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Rupert
Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
Post Options Quote Reply Posted: 13 Feb 18 at 7:25pm |
That'll feel 2 feet longer! |
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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