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Planing hulls.


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#101 ita 16

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Posted 25 May 2013 - 08:11 PM

Thanks Chris, Can you see everything? Movies, photos?

#102 Chris O

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Posted 25 May 2013 - 08:20 PM

This one answers my question nicely. Very clean work. The videos are all very crisply shot and with a good amount of information as to how the boat works and what is going on as you drive it.

 

581794_159289507576850_1956039088_n.jpg



#103 Doug Lord

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Posted 25 May 2013 - 10:04 PM

ita 16, for some reason I still can't see what you posted, but if the cat in the above picture is part of it -nice job! Three questions:

1)-why a "T-Foil" and

2)-how do you control altitude?

3)- does the on-deck plate allow you to control angle of incidence of the vertically lifting hydrofoil?

Like the outboard location of the daggerboard trunk-very good idea.



#104 david r

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Posted 25 May 2013 - 11:02 PM

You seem to quite a good craftsman and hard worker- impressive stuff.

Would like to see the vid.  Can you put it somewhere besides facebook for us nonfacebook types?

if you don't mind, a couple questions:

wouldn't a large portion of the weight of the boat be resting on that liteweight stainless rudder hold down, or is my thinking off?  the same may be true for whatever holds the boards down wouldn't it?

Also how do the rudders act when dragging behind the boat before they are locked down.  i have been wondering about that issue and figured the daggerrudder system would prolly be a good solution.

 

 

jollyrodgers.net



#105 ita 16

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Posted 27 May 2013 - 11:41 AM

yess, adjustment system with the plate allows me to adjust incidence foil, foil T I adopted to balance the torsion of the board straight , position of rudder allows you to have more space for the feet and less turbulence coming from straight boards. the rudder have a very simple system to adjust vertical angle of the rudder when you come back on the beach, it is a little hard but you can control the direction if you do not go fast. I only did 2 hours of testing, I still have much to understand and learn, I also have more courage when S.9 begins full flight, is impressive, I'm not used to this way of boating.
Thanks to all to appreciate this work, your experience is also helpful to understand more.

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#106 ita 16

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Posted 27 May 2013 - 11:57 AM

soon as possible to I make a movie on youtube, at the moment you can see some lousy short movie on FB



#107 bobber

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Posted 27 May 2013 - 03:17 PM

Excellent work! The boat looks like a lot of fun - small, light weight, and an excellent platform for foil testing. Do the T foils bolt to the bottom of of the daggerboard or are they bonded? If they are bonded, what is the procedure for removing the foils from the hulls?

 

Thanks for sharing this project and good luck with further testing!



#108 ita 16

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Posted 27 May 2013 - 04:32 PM

Excellent work! The boat looks like a lot of fun - small, light weight, and an excellent platform for foil testing. Do the T foils bolt to the bottom of of the daggerboard or are they bonded? If they are bonded, what is the procedure for removing the foils from the hulls?

 

Thanks for sharing this project and good luck with further testing!

 

thanks bobber, for this first test I glued the T foil, more resistance to breakage, in the future I will also test on bolted T foil but it will be difficult to realize because board and foil sections are very small. currently I insert board + Tfoil from the bottom of the hull and then apply the rope locking adjustment in the top. with foil fully raised the Draught is 5 cm.



#109 Doug Lord

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Posted 27 May 2013 - 08:02 PM

Ita 16, take a look at this sketch by Greg Ketterman. According to him it shows the difference in drag between a t-foil confronted with leeway and an "J" foil confronted with leeway.("J" foil pointed inboard on eith side only).

He shows that with a t-foil, there can be high and low pressure on the same side-and where they meet is a source of drag. Bears thinking about: (from a paper by Greg)

 

Click on the illustration-

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#110 ita 16

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Posted 28 May 2013 - 10:46 AM

Ita 16, take a look at this sketch by Greg Ketterman. According to him it shows the difference in drag between a t-foil confronted with leeway and an "J" foil confronted with leeway.("J" foil pointed inboard on eith side only).

He shows that with a t-foil, there can be high and low pressure on the same side-and where they meet is a source of drag. Bears thinking about: (from a paper by Greg)

 

Click on the illustration-

it is interesting to this drawing, he's right. I had to make compromises, in fact I have a bit of friction at the ends of the foil. the problem is that design only on paper does not assess other variants, theoretically L foil is perfect but in reality operation is unbalanced, its center of gravity for maximum thrust is far away from the board, this creates a twist of the board that causes a change in the incidence board , maybe this is good or maybe bad, maybe in the future I will do this test. There is also the factor weight and cost, a foil L must be much more stronger than a T foil, then material, weight and cost increase. all this is the same also in the T rudders. imagine, when the  windward L rudder out of the water, the rudder under wind will rotate  making you bear away. this could be good or bad. test it too.



#111 Chris O

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Posted 28 May 2013 - 12:59 PM

A major Bravo! to ita 16 for addressing the factual limitations of foil design and operation. Some of our foil proponents never go near the discussion of foil concerns and I find it more than refreshing that our friend from Italy sees it as a method for opening-up the conversation and inviting others into the mix. Thanks for the candor.

 

I'm wondering what might be in the discovery process regarding the transition zones of boat performance with a planing hull form and the use of foils. We have displacement mode transitions to planing and there is a zone where the hull leaves the planing state and begins to fly. I realize that it's early the development process, so perhaps some of the data is still being worked through.

 

Is it possible that the foils could be reduced in size to the point where they are merely providing a low drag assist to the planing state?

 

Perhaps curved boards are a better component for a planing hulled vessel over a wide array of wind and sea states?

 

Do the foils add sufficient drag that they hamper low speed operation for this type of hull shape?

 

Is it faster and easier to sail in a wider wind range without the lifting foils and simply operating on plane?

 

Would the boat operate much better as a foiler if it had a more traditional, slender body, hull form... foregoing the planing function entirely?

 

Pretty exciting place to be, ita. I look forward to more of your discovery process and thanks, again, for being bold and gracious enough to openly discuss your work in progress.



#112 ita 16

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Posted 28 May 2013 - 05:57 PM

A major Bravo! to ita 16 for addressing the factual limitations of foil design and operation. Some of our foil proponents never go near the discussion of foil concerns and I find it more than refreshing that our friend from Italy sees it as a method for opening-up the conversation and inviting others into the mix. Thanks for the candor.

 

I'm wondering what might be in the discovery process regarding the transition zones of boat performance with a planing hull form and the use of foils. We have displacement mode transitions to planing and there is a zone where the hull leaves the planing state and begins to fly. I realize that it's early the development process, so perhaps some of the data is still being worked through.

 

Is it possible that the foils could be reduced in size to the point where they are merely providing a low drag assist to the planing state?

 

Perhaps curved boards are a better component for a planing hulled vessel over a wide array of wind and sea states?

 

Do the foils add sufficient drag that they hamper low speed operation for this type of hull shape?

 

Is it faster and easier to sail in a wider wind range without the lifting foils and simply operating on plane?

 

Would the boat operate much better as a foiler if it had a more traditional, slender body, hull form... foregoing the planing function entirely?

 

Pretty exciting place to be, ita. I look forward to more of your discovery process and thanks, again, for being bold and gracious enough to openly discuss your work in progress.

thank you very much Chris. you make me want deeper into the subject. Now I say things I should not say on my research. I think the full-fly is a dangerous practice, very expensive, difficult to maintain on the beach and in the water, and I believe that in a race with many boats you can hurt a lot, especially if you are not a super expert, full-fly is difficult to manage and govern, has a range of wind and wave very limited in Moth everything is easier but cat is really complicated, it's the same difference between a 3D and 2D, the cat has the third dimension, I think it's a discipline just to make speed for fun, I do not see the full-fly in races of beach-cat. semi-planing hulls are an excellent option for fleet racing, fun, affordability, ease of use, safety, etc.. curves boards are good for stabilizing the cat with all conditions of wind wave but I do not see in these the possibility of full-fly, these boards do not generate sufficient thrust to fly then the crew should be very aft to reduce weight on tables, but so must use foil rudders very large, this allows you to fly the cat under very restricted circumstances, but the flight control stable and constant all depends on how good the pilot.

with the S .9 I searched the best of each type of solution among those that I listed above, so I made the second goal assisting the glide with a full-fly sistem of size  low, without any control system of the wings, very simple . allows me to fly just above the water without risking catastrophic falls, maintaining a constant asset, reduced pitch, increased speed, full control of the cat in all conditions wind-wave, I tested this with 20 knot winds and 1.5 m wave, the S .9 is less than 14 feet. however, this system of foil is also good for making full-fly but it is something that I have yet to learn to use, I only have 2 hours of training with this system. I think this is the future for beach cat "extreme". I also want to say that my basic purpose is not to create a cat with exaggerated performances, but a small cat with which you can do everything, cheaply, in little time, with maximum security, apply the foil when you want to fly in 10 minutes without foil can glide. I still have 2 goals to be achieved, in 1 month I think I'm ok. this job-I passion has been handed down from my father, I do this for a hobby NOT to become rich, then I have no problem divulge my knowledge , probably someone will take advantage of this but it is not new for us, it happened many times. I hope my English is understandable, I hope that my thoughts may be helpful to understand what you can not test in person. thanks again for your interest.



#113 ita 16

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Posted 12 June 2013 - 11:08 AM

continue the test well, and planing assisted seems more and more the best option to compete in the race. however have fun in search of full-lla fly,
we fly farther and farther away.


#114 Doug Lord

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Posted 12 June 2013 - 01:24 PM

You flew some of the time-hard to see but the video shows great performance. So you think the best combination is lifting foils + planning, right? Are you satisfied with the T-foils?

#115 ita 16

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Posted 12 June 2013 - 01:49 PM

You flew some of the time-hard to see but the video shows great performance. So you think the best combination is lifting foils + planning, right? Are you satisfied with the T-foils?

yes, I think you need a combination of planing assisted by foil on race. maybe in the future we will also see the beach cat full- fly in the race. at the moment I do not think it is possible especially on a cat with a single crew. I'm happy with T foil, light and very efficient but I would like to test other profiles and shapes, but I find it difficult to manage the increase in lift caused by increased speed. the shapes V, J, C, etc. reduce the surface when the boat gets up flying the T foil does not help in this but they are more efficient.



#116 Doug Lord

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Posted 12 June 2013 - 01:57 PM

 

You flew some of the time-hard to see but the video shows great performance. So you think the best combination is lifting foils + planning, right? Are you satisfied with the T-foils?

yes, I think you need a combination of planing assisted by foil on race. maybe in the future we will also see the beach cat full- fly in the race. at the moment I do not think it is possible especially on a cat with a single crew. I'm happy with T foil, light and very efficient but I would like to test other profiles and shapes, but I find it difficult to manage the increase in lift caused by increased speed. the shapes V, J, C, etc. reduce the surface when the boat gets up flying the T foil does not help in this but they are more efficient.
==================
I'd like to understand why you think the the T-foils are more efficient than an "L" foil. From what I saw in Kettermans analysis(posted earlier) the inward pointing "L" seems more efficient than a T-foil.
Good luck-you do really good work!

#117 ita 16

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Posted 12 June 2013 - 02:15 PM

 

You flew some of the time-hard to see but the video shows great performance. So you think the best combination is lifting foils + planning, right? Are you satisfied with the T-foils?

yes, I think you need a combination of planing assisted by foil on race. maybe in the future we will also see the beach cat full- fly in the race. at the moment I do not think it is possible especially on a cat with a single crew. I'm happy with T foil, light and very efficient but I would like to test other profiles and shapes, but I find it difficult to manage the increase in lift caused by increased speed. the shapes V, J, C, etc. reduce the surface when the boat gets up flying the T foil does not help in this but they are more efficient.
==================
I'd like to understand why you think the the T-foils are more efficient than an "L" foil. From what I saw in Kettermans analysis(posted earlier) the inward pointing "L" seems more efficient than a T-foil.
Good luck-you do really good work!

yes, I think that L foil is better, I hope to test this in a short time. the problem of L foil is that it needs a structure very reinforced because the surface which gives lifting is unbalanced by a single side of the board, creating twist and weight increase. I hope to resolve this problem. thanks Doug, Greetings



#118 Doug Lord

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Posted 12 June 2013 - 02:34 PM

Could you use a curved foil(for altitude control) + "L" like several foiling cats are using? Of course, they also use a three foil configuration-might be too much work on a singlehander-unless you come up with a really innovative solution*-which I think you could do. I guess you'd have to change out the trunks, too? Again, good luck whatever you do....

*some simple way for a singlehanded skipper to raise one board and lower the other during a tack or gybe






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