Kite Surfing

Yes, it's broken in a straight line between the footpad steel inserts. Almost right in the middle. Interestingly, only a thin, first wood veneer cracked. Hopefully, a few glass layers would prevent this.

Unfortunately, took it for a ride in 20-25knts, for which wasn't designed for. 2-3m jump, landed dead flat. My bad.

Also, the 6mm bamboo ply is quite heavy, not sure how heavy your board will be!

If you like, I can measure my bamboo leftover and weight it to give you a clue?

Personally if my boards can't handle what ever I through at them, they fail the pass test. So if I can handle it in 20 to 25 knots then the board should be able to handle it. As for jumps and landing flat, well I think you need to make the board stronger, you can't always guarantee how you will land the board. Note your other option is to add more bulk to the board if making a new one, so some weaker (lighter) layers in the middle of the layup will make it stronger.

In simple terms your stress =

M*y/I

where M = bending moment. Take this as a constant.
y = distance from the middle of the board to the extreme fibre, if you have a symmetric layup, then y = half the board thickness.
I = moment of inertia = b*h^3/12
b = width of board, take this as a constant
h = thickness of board

With these two simple formulae you can easily and quickly see how much your stress drops as the thickness h is increased. For hollow sections the equation for moment of inertia is a bit different. Also if the stiffness/orientation of the layers are different, again the equations change. Hence why I said "in simple terms" to give a feeling for the changes.

What orientation did you use for the glass plies, how many plies did you use? 0 - 90 degrees or 35 - 135 degrees to the axis of the board for the top/bottom layer ? 0 - 90 would be strongest especially considering how you board broke. Often though the top and bottom layers are at 35-135 degrees so they are not the critical layer, then the next layer is 0 - 90 degrees. It's a way of protecting the critical layer.

Any way ....... how's it going Plummet, decided on your design, have you started building? Would be cool if you post some pics as you build the board.

Regards,
Norman

Oops double post, sorry.

Yes, it's broken in a straight line between the footpad steel inserts. Almost right in the middle. Interestingly, only a thin, first wood veneer cracked. Hopefully, a few glass layers would prevent this.

Unfortunately, took it for a ride in 20-25knts, for which wasn't designed for. 2-3m jump, landed dead flat. My bad.

Also, the 6mm bamboo ply is quite heavy, not sure how heavy your board will be!

If you like, I can measure my bamboo leftover and weight it to give you a clue?

did the board snap in half? or is it simply cracked? if cracked then its easily repaired. post up a pick and we can advise.

ps Even though i'm asking questions about board dimensions i am an accomplished board builder of longboard skate boards and landboards..... so i have the kiteboard building skills lurking.

SB I'm still formulating ideas in my head. I also want to ride some other gues standard rectangle boards first too before i make a decision on what to build.

i may end up building a normal size deck first....

in other news i'm also churning a longboard skateboard design in my head also. that one is tricky. intergrated base plates in the deck and carbon hangers with sipherical roller bearings. i'm not sure which build will comence first.

The board just cracked, and probably it can be repaired. Not sure about the needed effort tho.

Will definitely build more boards this year.


Did you see this as the lite wind board:

http://www.thekiteboarder.com/2011/02/litewave-2011-wing-analyze-this-board-review/

Also, Matt's blog is resourceful (you guys probably know that already:)

http://myvirtualshed.blogspot.com/

Cheers,

D.

i like that lite wave design. i may try that sort of thing first and then trim the tips if i don't like it.

I also had a crazy idea. run a reverse camber edge like this light wave on one side and a normal more round edge on the other side. use 2 way surfboard style bindings and flip the board around from light wind monster to high wind charger on the fly... what do you think?

Two way pads, sounds interesting but will there be a compromise with comfort. Standard twin tip bindings are set duck style (asymmetric), whereas a two way pad system would have to be perpendicular to the board (symmetric). Never tried the symmetric alignment so don't know whether it would be comfortable or not. I know with my CrossBow Mountain board getting the foot pad angle is crucial for comfortable toe side riding.

Still a two pad system opens up opportunities for unidirectional boards, tired of going toe side -- no worries swap the board around.

So what are the opinions out there of these two way pad systems? Or is it a case of where they are used on surfboards the boards are wide enough to have two pads on each end so they can be set asymmetrically.

i've got a set of those pads on my surfboard. the ones i have aren't than comfortable but good ones are.

i've decided i like this lightwave wing style board



i'll make something like that. perhaps not as flash. but i can sure as hell make a board as flexy and as stiff as i want. ..... .. . .

Has anyone tried using Paulownia planks?
Been trawling the web for some info about making a lightwind board, probably an Alaia, and these guys seem to be selling planks for kiteboards as well http://www.portphillip.com.au/surfboards.htm it's light weight and doesn't absorb water.

Plummet,

this might be a great idea!
You've got the outline for this board already in the Excel template from Matt's site (DB's board, Template selection 9). Of course, your idea of asymmetrical board is not covered by this tool.

As for Paulownia, Matt has already built one. I'm thinking to do the same but still have the bamboo leftovers.

D.

wow. that board spreadsheet is detailed!.... way to detailed for this white man.

I'll make a basic press, press it and build it, ride it, stiffen it if need be.

Detailed yes, but for basic printout into the PDF and than taking this to ie. SnapPrinting should be ok?

Otherwise, how do you guys draw the outline? I'm using a carbon paper on my ply wood. Is there some better and faster method?

I'll just manually shape a half or quarter template either in ply or cardboard and use that. It wont be as precise as the excell spreadsheet way. but i'll be able to adjust my design in actual size as i make it. I'll work out a few critical dimensions use them as a datum and then go with the flow with my shaping tools uptill i get a pleasing shape!.

So it will be mainly eyethometer. much like a surfboard shaper. Seems to be my style. I don't get too techy. then i adjust on the fly if my shape doesn't work. i wont be bothering with rails. can't see the use in them really. So i'll be able to easily shape it further if need be once i've done some water tests.

I'm getting quite excited actaully its been a while since i've built a board.

Ive been reading through this with interest.

I tried to use the program to set up and print the outline of the board but to my annoyance the external programs you need to print to pdf files just arent compatible with my system( or im just damn stuuuupid )

After sitting back and being really annoyed with myself it dawned on me.

I used to use google sketchup to convert DXF files to g code a while back . Plus i have designed and eventually built pontoons in scetchup after printing out the plans in pdf form.

What i did was still export the dxf file out of the excell sheet.
Open Google sketchup and imported it into that. It opens up with no worries and puts the outline there.
What i did then was trace around the imported outline, then exported/saved in into pdf format

Now i have been able to print out the outline of the board on multiple sheets ready to be traced out

Awesome effort PeterJ!

Maybe an suggestion to add as a comment on Matt's site?

How do you trace (back to my previous question:), and what are you building?

I am fooling around with making a board.
I printed out the shape.
But i found that it had to be at 75% he original size otherwise the board was going to be 2 mtrs long.

I print it, then tape it down to make the full sheet and then glue that down on a piece of ply. Let it dry and then out with a jigsaw and cut the outline.
In the past i have made templates for stitch and glue pontoons and did the same but used a sharp stanley knife to cut out the profile in 3 mm ply.

It's a good point about posting it.
I'm considering starting my own blog going through what im learning and the way to kiteboarding.
Or over the weekend i can do a heap of screen shots on making an outline in sketchup and post it.

Edit.....
Here is a screen shot from sketchup with a board outline, still with all the guide lines ( good idea to keep some for lining up the individual sheets)


If anyone wants, i can put a full tutorial on how to do it at some stage.

Regarding transfer from computer to physical board out line. I print to an A3 printer I have. I keep that printer just for that as it shots only on one of the coloured guns. I ensure that there are alignment marks on the print outs, lay the sheets out a pair at a time and use sticky tape to glue them together. I used to use paper glue, but so far have only used the plans once, so now going for the easier option of sticky tape as it only needs to last for one board build. I then lay the plan on top of the board. I carve them out of wooden planks. I then use an awl (pointy thing) to puncture a small pin pricks through the paper and on to the wood plank. I then join up the dots on the wood plank with a biro and a ruler. I generally have a dot to dot spacing of 20 mm and even closer at the tight radii at the board tips, so a ruler does the trick nicely. At the tight radii I might even join up the dots free arm. There are draftman's french curves or those springy rubber things that can be used to do the tight curves if you are really keen, but free hand is good enough.

A rough cut with a saw, then get the outline shape nice and smooth with a hand planner, using the biro markings as a guide. Any rocker I put in at the ends is Plummet style, using my eyeballometer. Don't bother with carbon paper, would need too much of it and besides who sells that stuff any way these days.

For some board designs it starts its life out as a rough hand sketch on butchers paper, I then get out the ruler and measure some points along the sketch (horizontal and vertical positions), feed that into my computer/drafting software where I do spline fits to get a nice smooth shape, then print out and follow the steps above.

Regards,
Norman.

After following the various threads I am also keen to make a light wind board approx 150 x 43cm, especially after today seeing Spartan out on his new plank at Altona doing some crazy water-to-land amphibian action on sandbanks at low tide

I have access to ideal equipment (spindle moulders and a 12 x 8 foot vacuum table with thermal control) so I am thinking of trying a lightweight epoxy composite. Ideally I would like a concave and some rocker at the tips.

With all your experience does anyone have any suggestions for a synthetic core option? I was thinking of Corecell but dont understand the issues around achieving a good shape!

Thanks for any help.