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 Post subject: Re: Opensource Courseboard
PostPosted: Mon Jul 16, 2012 10:31 pm 
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Joined: Mon Oct 08, 2007 4:39 am
Posts: 544
Printed not CNC. Additive process like a inkjet printer but layer on top of layer.


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 Post subject: Re: Opensource Courseboard
PostPosted: Tue Jul 17, 2012 3:22 am 
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Joined: Sun Jul 15, 2012 9:32 am
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Location: Tauranga, New Zealand
My bad, 'Cnc, and also your recycled plastic'
would the plasitic still be able to have a low density and be light? a long time to print out with 3d printing, that will take a while XD


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 Post subject: Re: Opensource Courseboard
PostPosted: Tue Jul 17, 2012 5:32 am 
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gbleck wrote:
I'd say no cutouts and a flat bottom nose to a wide diamond tail.

bradn wrote:
I will remove the cutouts, don't need them unless going >30 knots anyway



Just curious what is the basis for these suggestions?
If you want to do an open source design, we'd need to indicate not just what but WHY we are making these suggestions. Otherwise this will be little more than a drafting project.

Some points of reference should be (not necessarily limited to)

a) other successful designs,
Example (information false): Every raceboard that has podiumed this year has a diamond tail. flat tailed boards appear uncompetitive (show race results)

It's hard to argue with FAST. So even if it does NOTHING it's obviously not hurting performance much so if all fast boards are waxed with snake oil, I am happy to accept the opensource board will get snake oil until it is proven that mouse milk is way faster. .

b) accepted planing/hydrodynamic theory (Information false)
Example: Based on the size of the cut outs, the angle of trim required to have the cut outs effectively out of the water would be less than 2 degrees. In order to create board lift of 180lb at this trim angle would require a velocity of 30 knots and would create a reduction in wetted surface area of xx% and an expected drag reduction of yy Assuming an original wetted surface area of ww ft^2, (attach references)

c) Objective Test results
Example (information FALSE...just getting the idea across. )
I've ridden two boards one with a diamond tail and one with a flat tail, Using my GPS and windspeed data from ikitesurf, I was consistently able to point xx degrees higher into the wind on the diamond tailed board and maintain higher velocities at lower angles of point. (attach data and conditions)

d) Subjective test results:

Example (information FALSE): If I use a fins greater than 45 cm I get flipped over the front of the board as soon as the board starts getting any speed. So at 50 cm, I'm concerned this design will have too much fin.


Last edited by Johnny Rotten on Tue Jul 17, 2012 1:23 pm, edited 2 times in total.

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 Post subject: Re: Opensource Courseboard
PostPosted: Tue Jul 17, 2012 10:11 am 
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Joined: Sun Jul 15, 2012 9:32 am
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Location: Tauranga, New Zealand
@ Johnny
I read on a forum page that they tried to do use cutouts, similar to formula, but there was no improvement until roughly 30 knots, since most of the time when racing, you are not going anywhere near 30 knots they removed them.

what about having the back corners on slight angles, this might help to drive the board onto its leeward rail for going upwind?
I read somewhere that they have also tried putting a slight vee in the nose, but it was hard to control and had no advantages at all.

does anyone have any other ideas instead of tri fin setup with 2-5 degrees cant? (except north)


Last edited by Bradn on Wed Jul 18, 2012 4:41 am, edited 1 time in total.

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 Post subject: Re: Opensource Courseboard
PostPosted: Tue Jul 17, 2012 1:02 pm 
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Sorry Bradn all the information I put in was FALSE I was just trying to demonstrate how we should identify the source and conditions when presenting information...sorry it was late,.. I've since edited my post.

Bradn wrote:
@ Johnny
I read on a forum page that they tried to do use cutouts, similar to formula, but there was no improvement until roughly 30 knots, since most of the time when racing, you are not going anywhere near 30 knots they removed them.
what about having the back corners on slight angles, this might help to drive the board onto its leeward rail for going upwind?
I read somewhere that they have also tried putting a slight vee in the nose, but it was hard to control and had no advantages at all.

Do you think that you could point higher on the diamond tailed board because it could rail easier? (maybe the square tailed board could not because of the corners digging in - assuming that the front of the board lifts up slightly as well when going upwind on the rail )
was there a big difference in the fins of both of the boards?

does anyone have any other ideas instead of tri fin setup with 2-5 degrees cant? (except north)

Thanks for the info Johnny


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 Post subject: Re: Opensource Courseboard
PostPosted: Wed Jul 18, 2012 4:43 am 
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Joined: Sun Jul 15, 2012 9:32 am
Posts: 87
Location: Tauranga, New Zealand
Ah okay
I just thought that you meant that 'a)' was false


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 Post subject: Re: Opensource Courseboard
PostPosted: Wed Jul 18, 2012 10:27 am 
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Joined: Tue Feb 07, 2012 8:56 pm
Posts: 26
I think IKA will not register the boards made in various places and various layups.
Making a mold is not a problem. I plan to make one after the summer.
But what can you do with the mold? Inject PU foam in double wall sandwich? Attach some stringers as WoodeCookie? It is not an easy task and quality would be very different from builder to builder.


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