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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Fri Feb 07, 2014 11:05 pm 
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Hi Hawaiis,

I really appeciate your wooden foil. Real aloha spirit :wink:

By the way, what do we obtain when the orangutan skips the sailboat ?
Something like this ? A monohull climbing to the trees ?



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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sat Feb 08, 2014 12:47 am 
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C A R A F I N O 2014 wrote:
I see 60% of the board out of the water. So what do you need that part of the board for?


coleman wrote:
the volume in the nose of the race board is what allows the board to pound over the chop at high speed. it provides stability and i am certain it is essential. without there would certainly be a loss of control.


You stopped me just in time! After reading the earlier post I was going to cut the forward 60% of my raceboard off :wink:

I was really excited when Carafino came out with the news of lower cost hydrofoil boards earlier this year, but I have become increasingly skeptical with every successive post:
-A lot of the design choices seem counterintuitive to me
-Bashing every other manufacturer for copying when the other manufacturers seem to have caused this sudden boom in hydrofoil interest during the time that Carafino was out of the market for the last 2 years.
-The boards were originally 30% less money than the next cheapest competitor, then 2 for 1 at that price, but only if you send your money overseas before there is any evidence of an actual product :-?
-It's not clear if any prototypes of these new designs were made and tested. The text says (vaguely) that it has been tested but there are no pictures or video, only computer graphics
-The description of the design philosophy of this raceboard doesn't make sense to me. It jumps back and forth between catamarans, planing hulls, to displacement hulls. A lot of talk about a wave piercing bow, but the nose of the board in the picture is flat, not pointy? Also, how can it be designed to pierce through waves and also create large amounts of lift to lift the nose up over waves?

I hope it all works out and the boards are a great product at a great price. If they are, I'll be first in line to buy one, but right now...


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sat Feb 08, 2014 4:11 am 
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Location: Miami @ 6" Flat Butter!
davesails7 wrote:
The description of the design philosophy of this raceboard doesn't make sense to me. It jumps back and forth between catamarans, planing hulls, to displacement hulls. A lot of talk about a wave piercing bow, but the nose of the board in the picture is flat, not pointy? Also, how can it be designed to pierce through waves and also create large amounts of lift to lift the nose up over waves?
The new trend is pointing to that direction of the new raceboard design what Carafino is talking about.
Some people already tried similar design and worked, so there is nothing to be skeptical about :jump:

DrLW


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sat Feb 08, 2014 10:48 am 
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Hydro Phil wrote:
Hi Hawaiis,

I really appeciate your wooden foil. Real aloha spirit :wink:

By the way, what do we obtain when the orangutan skips the sailboat ?
Something like this ? A monohull climbing to the trees ?


The sailboat class in your video is a 6.5meter class, they are limited by the length to 6.5m, so it is logical to make a potato looking boat to get the maximum volume. Surfboards are made like that too, so they can easily fit in the trunk. Hydrofoil boards, however spend most of the time not touching water, so a big fat board will be a liability in terms of aerodynamic drag in the air, and hydrodynamic drag when touching water.


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sat Feb 08, 2014 12:38 pm 
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Talking about board would not be necessary if we were able to stay airborne all the time!
Even without talking about starting from lying in the water, when you are touching the water while riding you want to avoid drag into the water, the board sinking etc...
Talking about drag in the air is almost un-necessary and irrelevant for almost all the riders, unless you're in the same category as Marc Blanc or J.Heineken!! How many riders concerned with speed over 30 knots?? If you are not able to keep an average speed of 25knots, then you're possibly in the category that won't give a damn!
Unless you want to keep the volume down for ease of transport (or less inertia that makes a board more fun to play with) you'll need a fat board.
The shape of the board will help a lot when recovering from touching the water: avoiding being ejected from the board and to keep the speed as high as possible for the next take off.


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sun Feb 09, 2014 11:06 am 
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Location: Tauranga, New Zealand
aero drag of a slightly larger volume board < aero difference between a larger rider and a small rider (?) e.g. not hugely important and just a silly marketing point...

personally I would ride a larger volume board any day
in very light winds it has more volume to support weight so would make getting upto foiling takeoff speed easier and you wouldn't sink inbetween strokes, example ;

foiling along and sail into a lull that does not have enough wind to sustain foiling, smaller board might sink and stop, loose apparent wind and kite drops. larger board has enough volume to support rider, continues slugging along at a few kn, the few kn more apparent keeps the kite in the sky and rider crosses the lull back to good wind.

specific situation but viable and you get the idea..

similar principle for the moths - they could chuck on larger foils and get up really early but it is more efficient to use smaller foils and in super light wind, just stay off the foils.


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sun Feb 09, 2014 1:03 pm 
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Location: France
Bradn,
I agree with your thoughts, and it seems that the drag coefficient of what is happening below the h2o is far more important than what is happening on or above the surface, although this is also a factor to be considered, just much less. I would also think that from a structural point of view, a thicker rounder board is stronger, having a greater moment of inertia and no "corners, edges" to break, And safer if you come into contact with it unlike a thinner "pointy" board. Maybe more durable in transport as well?
A thicker board would allow a deeper, therefore stronger tuttle box, if this method is used for the strut to board attachment.
Saying that, I have seen guys foiling with flat thin wood boards ripping it up!
Please rephrase your last sentence concerning the moth. I think I get it, but could you maybe expand on your idea please. :thumb:
I have been thinking a lot about wings with more surface area, mostly for low wind situations, any thoughts?
It is true that when one sees MOTH foils they seem small!
WOW, is it complicated to find the correct parameters; Surface area, aspect ratio, cord profile, plan form ect.....
revhed


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Sun Feb 09, 2014 3:16 pm 
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Bradn wrote:
similar principle for the moths - they could chuck on larger foils and get up really early but it is more efficient to use smaller foils and in super light wind, just stay off the foils.


That makes sense. You can't design a foil to create the right amount of lift going 5 knots through the water that also makes the right amount of lift going 40 knots through the water (like the top racers are going on their race foils). The lift (for a given shape, size, angle of attack; ignoring cavitation) is proportional to the velocity squared, so you have 64 times more lift at 40 knots than at 5 knots! You have to design the foil to create the right amount of lift at the higher speeds and you have the larger volume board to float you until you get up to speed.

How big are the top foil racers' boards?


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Mon Feb 10, 2014 10:31 am 
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@davesails7: i disagree with your conclusions. with kitesurfing it is almost allways about dynamic lift. volume only creates static buoyancy. you only need static buoyancy when standing on board with virtually no speed at all. for example when you do a tack and fail to loop the kite on time volume prevents you from sinking.

i only can speculate why race boards feature so much volume but i think it has to do with the fact that in races you sometimes get into situations where you do not have enough power provided by the kite and your speed is really low (bad tacks, temporary lulls, before start). then you do not want to sink since it will cost you more energy to get back to planing.

as soon as you are moving only dynamic lift matters. if you move very slowly you need an outline with a large area to get planing earlier. this is one reason why race boards are so large. besides the fact that you need a certain width to be able to handle those monster fins.

back to foilboards.

aerodynamic drag is no issue. compared to the drag produced by the kiter the difference in drag produced between a thicker or thinner board is irrelevant. i think that the reasons why boards are getting fatter are pretty much the same as mentioned before. if you don't dive the kite hard enough after a tack and before start situations.

concerning the board touching the water in waves or if you just make a balance error and hit the water with the board, volume is again irrelevant. in this case you want to have enough scoop so the nose will not get caught. i wonder if the carafino board as in the first post features enough scoop. the width of the board is limited by the fact that you lean hard to one side when going upwind.

h.


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 Post subject: Re: Carafino: Race Board 2014
PostPosted: Mon Feb 10, 2014 6:22 pm 
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Kamikuza wrote:
:runaway: Is that the new Slingshot Space Pickle...?


No but this is. The new 2014 Spotz Pickle

Attachment:
SpotzPickle.jpg
SpotzPickle.jpg [ 270.47 KIB | Viewed 189 times ]


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