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Foiling M20?! #185540
07/19/09 02:35 PM
07/19/09 02:35 PM
Joined: Jul 2001
Posts: 256
North Europe, Sweden, Uppsala
Hakan Frojdh Offline OP
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Hakan Frojdh  Offline OP
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North Europe, Sweden, Uppsala
We had an A-cat regatta this week end at Marstrom and guess what....a M20 with curved daggerboards! These boards have more lifting capabilities than the A-class rules allow and at 17-18 knots with the boards fully down it lifts the boat completely from the water. That is not good since it jumps out of the water quite violently and sometimes threws the crew in the water. The boards where longer than they are in the picture but then it started to do the "thing" at 16 knots. When they sail upwind with this only parts of the hull are in the water and that enough to balance the boat, so it is a kind of "semi foiling". It's hard to tell how much foiling you want to get the best performance. The boards are level with the bottom of the hull in the picture.

[Linked Image]

/hakan

-- Have You Seen This? --
Re: Foiling M20?! [Re: Hakan Frojdh] #185543
07/19/09 03:08 PM
07/19/09 03:08 PM
Joined: Jul 2004
Posts: 2,718
St Petersburg FL
Robi Offline
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If they are level, then heck yeah those are pretty long boards. Pretty cool to see the development going on.

Re: Foiling M20?! [Re: Robi] #185546
07/19/09 03:46 PM
07/19/09 03:46 PM
Joined: May 2003
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West coast of Norway
Rolf_Nilsen Offline
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Cool stuff. Wonder where we will be in 10 years.. Good to see that Marstrøm still work on/for small cats. I bet it will be a handful to make that work reliably and predictably. grin

Thanks Håkan

Re: Foiling M20?! [Re: Hakan Frojdh] #185547
07/19/09 04:15 PM
07/19/09 04:15 PM
Joined: Aug 2001
Posts: 1,307
Asuncion, Paraguay
Luiz Offline
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This boat needs small symetrical section T or L foils in the rudders.
When the main foils lift the bow, the symetrical section rudder foils lift the transom taking the hull out of the water. When the boat assumes a bow down attitude, the symetrical section rudder foils help keep the transom in the water.


Luiz
Re: Foiling M20?! [Re: Luiz] #185548
07/19/09 04:42 PM
07/19/09 04:42 PM
Joined: Jul 2001
Posts: 256
North Europe, Sweden, Uppsala
Hakan Frojdh Offline OP
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Hakan Frojdh  Offline OP
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North Europe, Sweden, Uppsala
T or L shaped rudders will make things more stable and has the potential to lift the boat in a more controlled manner but will it be faster? The C-class the foiling boat was slower that the "normal boats".

/hakan

Re: Foiling M20?! [Re: Hakan Frojdh] #185554
07/19/09 07:54 PM
07/19/09 07:54 PM
Joined: Aug 2001
Posts: 1,307
Asuncion, Paraguay
Luiz Offline
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Not in light winds, but they increase the top speed. The new 35ft hydroptere.ch will use a similar setup.

[Linked Image]


Luiz
Re: Foiling M20?! [Re: Hakan Frojdh] #185563
07/19/09 10:01 PM
07/19/09 10:01 PM
Joined: Jul 2002
Posts: 539
taipanfc Offline
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Originally Posted by Hakan Frojdh
We had an A-cat regatta this week end at Marstrom and guess what....a M20 with curved daggerboards! These boards have more lifting capabilities than the A-class rules allow and at 17-18 knots with the boards fully down it lifts the boat completely from the water. That is not good since it jumps out of the water quite violently and sometimes threws the crew in the water. The boards where longer than they are in the picture but then it started to do the "thing" at 16 knots. When they sail upwind with this only parts of the hull are in the water and that enough to balance the boat, so it is a kind of "semi foiling". It's hard to tell how much foiling you want to get the best performance. The boards are level with the bottom of the hull in the picture.

[Linked Image]

/hakan


Definitely need to be able to balance the boat so it is parallel to the water when foiling. Means adjustable AOA on the centreboards. Max lift when not foiling, and less lift when foiling as the increased speed keeps the boat up and out of the water.

Deeper rudders are necessary to ensure you can still steer and these don't ventilate by the hull rising up. T or L on the bottom means they act similar to the tail on the plane by ensuring the pitch of the boat is kept into line and you should be able to adjust this angle.

Moths lift at 7-8 knots of breeze, so more development can be done to bring this down on the M20. A huge amount of drag to have in conditions when not foiling.

Re: Foiling M20?! [Re: taipanfc] #185568
07/19/09 11:20 PM
07/19/09 11:20 PM
Joined: Jul 2004
Posts: 2,718
St Petersburg FL
Robi Offline
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Robi  Offline
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Maybe they are first developing lifting boards then work on the rudders, makes sense to me. Get the boat to lift off then control the attitude, one step at a time. This could be awesome.

Re: Foiling M20?! [Re: Robi] #185570
07/20/09 12:21 AM
07/20/09 12:21 AM
Joined: Jul 2002
Posts: 539
taipanfc Offline
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Originally Posted by Robi
Maybe they are first developing lifting boards then work on the rudders, makes sense to me. Get the boat to lift off then control the attitude, one step at a time. This could be awesome.


Maybe, but you do a lot of damage along the way. If the main foils lift, and then ventilate at speed (ie instantly loss all lift), then the whole nosedive is a helluva lot quicker. Mainly because the hulls are pointing downwards and then hit the water. Done that many many many times on the moth. The whole nosedive cartwheel experience a lot quicker than i have ever experienced on a cat.

Re: Foiling M20?! [Re: taipanfc] #185582
07/20/09 09:30 AM
07/20/09 09:30 AM
Joined: Jan 2005
Posts: 6,049
Sebring, Florida.
Timbo Offline
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I was under the impression the curved boards were not at all designed intended for full on foiling, rather for a smaller amount of lift to keep it from pitch polling going downwind?

There was a discussion about these curved boards some months ago on the A Cat Forum. I thought they said it was about stability and lift going downwind, not full foiling.


Blade F16
#777
Re: Foiling M20?! [Re: Timbo] #185583
07/20/09 09:38 AM
07/20/09 09:38 AM
Joined: Jun 2001
Posts: 733
Home is where the harness is.....
Will_R Offline
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Home is where the harness is.....
Originally Posted by Timbo
I was under the impression the curved boards were not at all designed intended for full on foiling, rather for a smaller amount of lift to keep it from pitch polling going downwind?

There was a discussion about these curved boards some months ago on the A Cat Forum. I thought they said it was about stability and lift going downwind, not full foiling.


I can't say for sure, but the boards on the A's, M20 and CFR type boats are WELL aft of a boat like the N20. I can't see them adding any lift to the bows.

Re: Foiling M20?! [Re: Will_R] #185587
07/20/09 10:58 AM
07/20/09 10:58 AM
Joined: Aug 2001
Posts: 1,307
Asuncion, Paraguay
Luiz Offline
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Luiz  Offline
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Asuncion, Paraguay
Originally Posted by Will_R
Originally Posted by Timbo
I was under the impression the curved boards were not at all designed intended for full on foiling, rather for a smaller amount of lift to keep it from pitch polling going downwind?

There was a discussion about these curved boards some months ago on the A Cat Forum. I thought they said it was about stability and lift going downwind, not full foiling.


I can't say for sure, but the boards on the A's, M20 and CFR type boats are WELL aft of a boat like the N20. I can't see them adding any lift to the bows.


If the goal is fore and aft stability, the foils should be placed forward of the main beam/mast and the rudder should be deeper. I would have chosen the ARC 20 configuration for experiments, with larger beams, overpowered and in carbon, if possible.


Luiz
Re: Foiling M20?! [Re: Hakan Frojdh] #185657
07/21/09 06:30 AM
07/21/09 06:30 AM
Joined: Jul 2001
Posts: 1,253
Columbia South Carolina, USA
dave mosley Offline
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dave mosley  Offline
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Columbia South Carolina, USA
Was this just a test, or do they plan on developing these new and longer boards. Im all for curved boards, but not ones with this much "performance enhancing" ability. While we are at it, lets do some blood doping too!


The men were amazed, and said, "What kind of a man is this, that even the winds and the sea obey Him?" Matthew 8:27





Re: Foiling M20?! [Re: dave mosley] #185658
07/21/09 06:56 AM
07/21/09 06:56 AM
Joined: Jul 2007
Posts: 976
France
pepin Offline
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pepin  Offline
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France
Originally Posted by dave mosley
Was this just a test, or do they plan on developing these new and longer boards. Im all for curved boards, but not ones with this much "performance enhancing" ability. While we are at it, lets do some blood doping too!
I don't understand your point there. I want development of new systems, rigs, daggerboard, sail, anything that can make our boats go faster.

I don't see the relationship between this and doping. At all. One is development, the other is cheating.

And frankly if in 5 years we have a foiling cat class I'll probably start thinking about migrating to it. I hope to get an existing class to allow foiling first, but given the current restrictions on curved boards in the F16 and A class I'm less than hopeful on that front, both blew it by changing their box rules to effectively end any attempt at foiling.

Foiling is awesome. I've been a passenger on a trifoiler once and that thing was a hoot. I watch the foiling moth with envy, but I know I'm too heavy for those, and I don't like the idea of spending my sailing sessions swimming. So I'm eagerly awaiting for someone to build a foiling cat for a reasonable cost we can create a class of.


Re: Foiling M20?! [Re: dave mosley] #185659
07/21/09 07:17 AM
07/21/09 07:17 AM
Joined: Apr 2003
Posts: 1,669
Melbourne, Australia
Tornado_ALIVE Offline
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Melbourne, Australia
Bannana boards can get very messy if you fly the hull too high as the Canadian C Class guys found out. When the windward hull flew too high, the leeward hull jumped completly out of the water and sent them crashing backwards into the tide. Luckly the boat did not capsize on top of them.

Article here - http://www.sailinganarchy.com/fringe/2006/banana_boards.php

[Linked Image]


Re: Foiling M20?! [Re: Tornado_ALIVE] #185661
07/21/09 07:53 AM
07/21/09 07:53 AM
Joined: Jul 2001
Posts: 1,253
Columbia South Carolina, USA
dave mosley Offline
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Pepin, not sure if you have followed the A Class vote a couple months ago, but there were some serious restrictions about length and other constraints. Im not saying that foiling is cheating, but its gone a bit beyond the premise of the curved boards intent(at least for the A Class)
If you want to foil, put some of those babies on your 5.2 and start your own class, but dont bring them into the A Class, we want something more "traditional".


The men were amazed, and said, "What kind of a man is this, that even the winds and the sea obey Him?" Matthew 8:27





Re: Foiling M20?! [Re: dave mosley] #185662
07/21/09 07:54 AM
07/21/09 07:54 AM
Joined: Jul 2001
Posts: 1,253
Columbia South Carolina, USA
dave mosley Offline
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dave mosley  Offline
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My last post sounded a little harsh, didnt mean it that way!


The men were amazed, and said, "What kind of a man is this, that even the winds and the sea obey Him?" Matthew 8:27





Re: Foiling M20?! [Re: Tornado_ALIVE] #185663
07/21/09 08:03 AM
07/21/09 08:03 AM
Joined: Jan 2005
Posts: 6,049
Sebring, Florida.
Timbo Offline
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Wow, looking at that C class cat pictured above, it is amazing to me that one skinny little board can cause that much lift, to lift the entire boat out of the water!

Are we sure there wasn't some other factor, like a puff just died while they were going fast, and they T bagged and that caused the lee hull to jump up so high?

What does a C class cat weigh these days?



Blade F16
#777
Re: Foiling M20?! [Re: Timbo] #185664
07/21/09 08:06 AM
07/21/09 08:06 AM
Joined: Apr 2003
Posts: 1,669
Melbourne, Australia
Tornado_ALIVE Offline
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Melbourne, Australia
Quote
After a few runs we had her up to 25 knots according to the tender following us with the GPS system. Sorry no pics on that so I guess it didn't happen. We find when we do go that fast the whole leeward hull lifts up about 6" and the boat is really cooking. As such we decide we really kind of like what the boards are doing for us. Conditions were described by Fred as "Spicy" and indeed they were about to get hot.

Once more back across the harbor, the boat is hauling butt when we get hit by a good sharp puff. All of a sudden the bows start to lift up as I ease the sheet, a lot, then while running forward as I look directly to leeward and I see the lee hull angle upwards to about 30 degrees, wherein the banana boards kicked into overdrive and the whole leeward hull flew up about 10 feet out of the water while we were doing 20 plus knots. At this point according to the guys in the tender, the entire boats was clear of the water launching up into the air for a brief moment.

Seconds later Fred and I hit the water and start getting tossed about as the boat teeters on the edge of total disaster, both of us waiting for the wing to land on our heads, skating along with the boat heeled to weather, we were fucked for sure. "How in hell do you dump a C-class to windward?" was all I could think.


Re: Foiling M20?! [Re: dave mosley] #185670
07/21/09 08:40 AM
07/21/09 08:40 AM
Joined: Jul 2007
Posts: 976
France
pepin Offline
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pepin  Offline
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France
Originally Posted by dave mosley
If you want to foil, put some of those babies on your 5.2 and start your own class, but dont bring them into the A Class, we want something more "traditional".
That's where I'm confused. If you want something traditional, why are you on a A class? The A class doesn't strike me as a traditional class, but as a development class, like the moth. The moth would be completely irrelevant if they had gone the traditional way instead of embracing something new and exciting...

And I don't want yet another foiling frankenboat, I'd like something based on a modern platform, with a chance to become a class. So the 5.2 is out as a foiling platform IMHO.

I'm not a A class sailor, but I truly believe the class vote to outlaw foiling was a setback.

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