| Re: A-class has hydrofoil problems!
[Re: CrisBolle]
#147161 08/30/08 02:48 PM 08/30/08 02:48 PM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
veteran
|
veteran
Joined: Aug 2001
Posts: 1,307 Asuncion, Paraguay | ...the side force on the sail is roughly 43 Kg (421 N). Each foil will have to supply 10.75 Kg of side force and lift 37.5 Kg (367 N). So your ratio of vertical to side force is 37.5/10.75 or an angle of 74 degree... In practice the boards are designed, angled and placed so that their lift resultant points toward the sails' CE in order to minimize (neutralize) the heeling moment. In this case they are true "Bruce foils". I believe you will need less than four 1m boards at work to fly an A Class at that speed. Maybe half of it. Also, it makes more sense to use one slightly larger canted board aided by a small horizontal foil in the rudder. Regards, Luiz
Luiz
| | | Re: A-class has hydrofoil problems!
[Re: Luiz]
#147162 08/31/08 08:57 AM 08/31/08 08:57 AM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | An original effort with large, externally-fastened surface-piercing foils on a Tornado in UK in the 1970s involved 4 foils. They soon abandoned 4 foil approach. Boat didn't turn.
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: A-class has hydrofoil problems!
[Re: dacarls]
#147163 08/31/08 09:07 AM 08/31/08 09:07 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | Dave, does you Jackalope A cat have T foils on the rudders too or just the two Bruce foils up front?
Blade F16 #777
| | | Re: A-class has hydrofoil problems!
[Re: Timbo]
#147164 09/01/08 08:51 PM 09/01/08 08:51 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | Yes- old Hobie fiberglass rudders have T-foils. The obsolete aluminum surface-piercing foils are located at the front cross bar to provide lift. It works..... So again- when are you going to appear at Lake Santa Fe this fall to fly it? Ya can't spend the whole year on-line.....
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: A-class has hydrofoil problems!
[Re: dacarls]
#147165 09/01/08 08:57 PM 09/01/08 08:57 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | BTW- the foiling A-cat seen in my avatar is 34 years old- epoxy/tortured marine plywood: going strong. In contrast- See the old Tornado discussion ongoing- fragmentary boats not worth restoring or messing with.
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: A-class has hydrofoil problems!
[Re: dacarls]
#147166 09/02/08 12:22 AM 09/02/08 12:22 AM |
Joined: May 2003 Posts: 4,451 West coast of Norway Rolf_Nilsen
Carpal Tunnel
|
Carpal Tunnel
Joined: May 2003
Posts: 4,451 West coast of Norway | BTW- the foiling A-cat seen in my avatar is 34 years old- epoxy/tortured marine plywood: going strong. In contrast- See the old Tornado discussion ongoing- fragmentary boats not worth restoring or messing with.
Gougeon cold moulded cedar tornados are still good, 30 years later. It is not the boats, it is the building methods and materials. Not many polyester/glass A cats from that era is still in use. Wood is an excellent material for boats, but time consuming and as such uneconomical for manufacturers. | | | Re: A-class has hydrofoil problems!
[Re: dacarls]
#147167 09/02/08 05:23 AM 09/02/08 05:23 AM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
|
Carpal Tunnel
Joined: Jan 2005
Posts: 6,049 Sebring, Florida. | Dave, I will get up there some day, I just hope there is enough wind when I do! BTW, about how much wind does it take to get it up on the foils and how fast does it go when you do?
I will be at the Wildcat regatta in Eustis, Oct. 4-5 (I think) will you be there? Can you bring the Jack a lope or will you have your other A cat? I'm trying to get both my twin daughters into Florida for next year (one is at Auburn in Vet School now spending a new set of sails every month) so if I can get them in, I will be up there quite a bit, at your house, as soon as I drop them off!
Thanks. Tim
Last edited by Timbo; 09/02/08 05:26 AM.
Blade F16 #777
| | | Re: A-class has hydrofoil problems!
[Re: Timbo]
#147169 09/02/08 08:36 AM 09/02/08 08:36 AM |
Joined: Dec 2001 Posts: 5,590 Naples, FL waterbug_wpb
Carpal Tunnel
|
Carpal Tunnel
Joined: Dec 2001
Posts: 5,590 Naples, FL | I'm trying to get both my twin daughters into Florida for next year (one is at Auburn in Vet School now spending a new set of sails every month) Thanks. Tim I'm tempted to say two words: Financial aid (or maybe 'student loan'). From what I'm hearing from financial gurus it's better to build your nest egg rather than fund their post-graduate education unless you're 100% positive they will be paying for your entire retirement. If they go off and raise a family, you're not guaranteed they'll pony up (pardon the pun) when you would like to sail off into the sunset... There are way more options to fund education than retirement...
Jay
| | | Re: A-class has hydrofoil problems!
[Re: dacarls]
#147170 09/02/08 08:40 AM 09/02/08 08:40 AM |
Joined: Dec 2001 Posts: 5,590 Naples, FL waterbug_wpb
Carpal Tunnel
|
Carpal Tunnel
Joined: Dec 2001
Posts: 5,590 Naples, FL | I like Dave's foil concept. Is it stable in chop/wave action?
Could something similar be designed for a sloop rig with spin? I think it'd be neat on an old Taipan 16 footer that didn't fit the F16 rule ...
Or even better, if you could just switch out the F16 compliant daggarboard/rudders with foils so you can sail either way... But that's probably asking way too much...
Jay
| | | Re: A-class has hydrofoil problems!
[Re: Hakan Frojdh]
#147172 09/06/08 05:50 PM 09/06/08 05:50 PM |
Joined: Sep 2006 Posts: 613 New Hampshire, USA windswept
addict
|
addict
Joined: Sep 2006
Posts: 613 New Hampshire, USA | I am looking at what the cost is to modify mine right now. I do not think that I want to tackle the issue myself this time. Just too much work and no time to do it. I think that it is good that this is happening and that most of us agree with the decision. In the US we took an informal poll across the country fleet by fleet. I know that there were some disenting votes, but the majority of the class in the states seemed to be of the opinion that this is truly no different than the canting boards that are already allowed. those of us at the back of the fleet have more to worry about than this issue. We need to be able to spend more time on the water and sharpen our sailing skills much more before this issue has any real impact upon us. This issue will play out at the top of the class somewhere between the top 20-40 sailors worldwide. If this truly has the impact that some believe it will, then it could be the deciding factor in National, Continental and World championships.
Tom Siders A-Cat USA-79 Tornado US775
| | | Re: A-class has hydrofoil problems!
[Re: windswept]
#147173 09/07/08 02:08 AM 09/07/08 02:08 AM |
Joined: Nov 2007 Posts: 17 Holland pieterjanned28
stranger
|
stranger
Joined: Nov 2007
Posts: 17 Holland | Hi guys ! After read most of the thread above , i am quite surprised about this fuzz.
How many guys of you did actually raced a 'banana borads 'boat or did race against a banana boards boats with a canted straight boards boat ?
i had the first curved boards a class flyer mk1 in 2004. tested it , raced it in all european regattas and 2004 -2007 worlds etc. Also sailed last european in La baule agianst Bob baier with his Nils Bunkenburg designed Nikita with the curved boards . ( last two season i race a normal fLYER mk2 ( Egner) with normal canted boards ad are faster then on my old boat with the curved boards which i still owned untill last month)
I can assure you it is really difficult to judge if there is a difference at all between curved boards an sthraight ones , an even more , if it is faster or slower.
There might be some circumstances that it feels faster , there might be some circumstances that is might feel slower .
But clear is± difference between straight old style ´in the hull plane´ boards and common canted board like all new boats is BIGGER then difference between the 'normal'canted boards and curved boards .
When you have EXTREMELY curved boards ( let say Radius 1200 mm) , then off course vertical lift vs lateral is a difference you can detect , but the downside becomes also clear...
so , what makes the differcence then ??
DOWNWIND SAILING TECHNIQUE!
There is much more then 'going flat 'or 'going wild'
There is some 20 degrees of sailing angle in between where you can fiddle around : going mild , or whatever you call it .
Highly dependable on -waves / chop -stable or gusty winds -current/ wave, wind direction -windspeed of course -sailors weight : 70 kgs or 85 kgs makes a hell of a difference is the choose of optimal angle downwind. -rig set up/ mast rake
my impression is that most sailors ( incl myself) are are 'too much sailing wild thing' as you understand what i mean . Quite often sailing slippery down at deep angles pays off better . Lighter guys can do that easier off course then the big guys .
Thats a differerence no curved / straight or canted board will make in a 100 years...
PJ | | | Re: A-class has hydrofoil problems!
[Re: windswept]
#147175 09/07/08 09:12 AM 09/07/08 09:12 AM |
Joined: Oct 2002 Posts: 1,226 Atlanta bvining
veteran
|
veteran
Joined: Oct 2002
Posts: 1,226 Atlanta | Tom, Why would you make this modification now? My boat has square trunks and I could easily add curved boards, but I'm going to wait to let someone else do the experimentation before I go cutting my boat up.
Plus are you racing the boat? Do you really think curved boards are going to make a differience in your results?
I'm not beating you up, I'm just asking because I was going down the same path. I wanted to add curved boards until I started having these same conversations with guys in the class, my sail designer, etc, and the consensus is the I need to work on my technique first, rig second, everything else is a distant 3rd.
Bill | | | Re: A-class has hydrofoil problems!
[Re: bvining]
#147176 09/08/08 08:03 AM 09/08/08 08:03 AM |
Joined: Sep 2006 Posts: 613 New Hampshire, USA windswept
addict
|
addict
Joined: Sep 2006
Posts: 613 New Hampshire, USA | Bill, I did not say that I am going to do this. Right now I have someone looking at the cost of doing one of two projects. The first would be straight boards, canted and the second is to look at banana boards. I do race the boat, but not enough right now for it to make a difference. I am planning on racing it quite a bit more over the next 12 months. If you read through my post it does state what you say which is that I need to put more into getting time on the water and that everything else can wait. How do you like your new sail?
Tom Siders A-Cat USA-79 Tornado US775
| | | Re: A-class has hydrofoil problems!
[Re: waterbug_wpb]
#147177 09/08/08 07:38 PM 09/08/08 07:38 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | Yes the A-cat with external foils is quite stable in a fresh breeze. Small sloop with spin and foils? If you are trying to run a spin at 20 knots across the wind- it will be difficult to manage. Re versatility: As previously stated, I put the hydrofoils on this boat in the thumbnail pic for the 38 mile Mug Race last year: little wind= poor result. This year I ran it in the Mug Race with a Hobie18SX spin in light air, and was only beaten by 5 larger, much more expensive cats.
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: A-class has hydrofoil problems!
[Re: pieterjanned28]
#147178 09/08/08 07:51 PM 09/08/08 07:51 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
old hand
|
old hand
Joined: Apr 2002
Posts: 805 Gainesville, FL 32607 USA | To quote Pieterjanned28: >normal FLYER mk2 (Egner) with normal canted boards are faster then on my old boat with the curved boards. Now we get to the point of the matter!
In Europe, apparently "Normal canted boards" are canted in. So I believe that is what he it talking about. In the US, existing A-cats have obsolete vertical trunks or trunks & hulls canted out like my Italian-built 2005 XJ. We have not seen many of these canted-in boats, except on Glenn Ashby's import with which he won the Worlds. I was there, and he was very effective downwind: No bugs on him upwind either.
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | |
|
0 registered members (),
567
guests, and 105
spiders. | Key: Admin,
Global Mod,
Mod | | Forums26 Topics22,405 Posts267,058 Members8,150 | Most Online2,167 Dec 19th, 2022 | | |