Contact   Imprint   Advertising   Guidelines

Convertible challenge

here you can exchange your experience and datas about your home build boards


BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Convertible challenge

Postby BWD » Sat Aug 18, 2018 12:47 pm

I’m building a new hybrid/convertible board, outline is paipo-ish, about 145 x 48, 10-12cm nose rocker.
Expected use 2/3 foiling, 1/3 planing.
Corecell and carbon.
The center will be stiff from foil mount to front foot.
I want flex in the ends. Not a lot, just a bit.
Rider weight range 75-85kg.
To any carbon experts around, how thin do you recommend I make the core in the flexible parts of the board?
9mm? Less? The blank is 20mm max. and I’ll keep this thickness through much of it for central stiffness and float...
Planning to use 2 layers hexcel as4 6oz 0-90 13x13 plus reinforcements for foil foot and fin areas.
Also have some unidirectional I can apply for extra longitudinal stiffness etc.
I have a few ideas (including adding some glass or cf on bias or 45/45 biaxial to mix), but curious how others would approach this project...

User avatar
rynhardt
Very Frequent Poster
Posts: 848
Joined: Wed Sep 11, 2013 3:51 pm
Kiting since: 2010
Local Beach: Leeupan
Favorite Beaches: Langebaan
Style: Freeride
Gear: GK vSonic 6 & 11
Cloud C2 17
Progeni Mutare
Xelerator door
Hoff DD140
Brand Affiliation: None
Location: Johannesburg, South Africa

Re: Convertible challenge

Postby rynhardt » Sat Aug 18, 2018 1:20 pm

Using 200gsm spread tow carbon @ 0deg on a TT, core can be 7mm centre tapered to 3mm at the tips. That's for a flat board with 5cm static rocker (each end) on a 140cm board.
With 85kg on it the rocker will go down to about 2cm.
Add concave and it gets stiffer.

User avatar
rynhardt
Very Frequent Poster
Posts: 848
Joined: Wed Sep 11, 2013 3:51 pm
Kiting since: 2010
Local Beach: Leeupan
Favorite Beaches: Langebaan
Style: Freeride
Gear: GK vSonic 6 & 11
Cloud C2 17
Progeni Mutare
Xelerator door
Hoff DD140
Brand Affiliation: None
Location: Johannesburg, South Africa

Re: Convertible challenge

Postby rynhardt » Sat Aug 18, 2018 7:37 pm

Actually just finished bagging a board tonight. Spread tow carbon on top, glass on bottom.. Gonna be interesting to see how the flex turns out..
Attachments
DSC_0060.JPG

BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Re: Convertible challenge

Postby BWD » Sat Aug 18, 2018 7:43 pm

I’m thinking mine will either end up with some glass or bias oriented cloth to get just a bit of flex...

fluidity
Medium Poster
Posts: 129
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2016
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Style: Wave, jump
Gear: Old Flexfoil 9, Switch Element V4 11m, Ocean Rodeo Prodigy 7m 2014, Nitro14m v6, Nitro9m v6 12mSwitch Legacy2
DIY CAD ultra-concave wave twintips 1500 and 130mm with my own fin designs. Easy upwind, awesome carving.

Re: Convertible challenge

Postby fluidity » Mon Aug 20, 2018 10:56 am

BWD wrote:
Sat Aug 18, 2018 7:43 pm
I’m thinking mine will either end up with some glass or bias oriented cloth to get just a bit of flex...
I've just done a semi infusion :o of a twintip with combined uni glass 150mm 850gsm top and bottom and double bias 650 gdm full width top and bottom over 10mm foamcore. Slower hardener next time!
I'm going to try to infuse the rest at some stage, seems a pity to waste it and I don't think the infusion seams will seriously compromise the strength.
But anyway, it's got about perfect flex for what I wanted. If you are going full carbon then you will have to go thinner than 10mm for any significant flex.
If you want to compromise then I'd recommend carbon on top with triaxial or part of it unidirectional along the long axis and unidirectional glass underneath with some carbon biaxial as the outside bottom layer.
Attachments
Untitled.png
Untitled.png (616.74 KiB) Viewed 471 times

BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Re: Convertible challenge

Postby BWD » Mon Sep 10, 2018 5:08 pm

I have had the convertible project on the back burner for a while, but getting ready to laminate.
I have been thinking of applying the 6oz carbon twill at 45 degrees to get strength, reasonably light weight and ability to tune flex with 0-90 patches and some uni, so the board will ride ok without the foil. I don't want it too rigid for enjoyment as a conventional board.
I have not seen this done very much though, applying 0-90 cloth on the bias to get 45/45 fiber path.
Is there any reason, other than "inefficient" use of cloth?
I have reinforcement patches and some small parts/projects in mind for the leftover triangles of cloth, so I don't see it as a waste for a one-off.
Any thoughts?

User avatar
rynhardt
Very Frequent Poster
Posts: 848
Joined: Wed Sep 11, 2013 3:51 pm
Kiting since: 2010
Local Beach: Leeupan
Favorite Beaches: Langebaan
Style: Freeride
Gear: GK vSonic 6 & 11
Cloud C2 17
Progeni Mutare
Xelerator door
Hoff DD140
Brand Affiliation: None
Location: Johannesburg, South Africa

Re: Convertible challenge

Postby rynhardt » Mon Sep 10, 2018 8:29 pm

BWD wrote:
Mon Sep 10, 2018 5:08 pm
I have had the convertible project on the back burner for a while, but getting ready to laminate.
I have been thinking of applying the 6oz carbon twill at 45 degrees to get strength, reasonably light weight and ability to tune flex with 0-90 patches and some uni, so the board will ride ok without the foil. I don't want it too rigid for enjoyment as a conventional board.
I have not seen this done very much though, applying 0-90 cloth on the bias to get 45/45 fiber path.
Is there any reason, other than "inefficient" use of cloth?
I have reinforcement patches and some small parts/projects in mind for the leftover triangles of cloth, so I don't see it as a waste for a one-off.
Any thoughts?
We generate a fair amount of waste. Our 200gsm alutex is 0/90 on the roll but we use it +45/-45.
And our 410 biax glass is +45/-45 on the roll but we use it 0/90. :o
Crazy, but it gives us the flex we want.
I have lots and lots of waste triangles :-?

PS. just be careful with patches with straight edges - they can cause stress risers at the edges. I've seen some guys feather the edges to compensate.

BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Re: Convertible challenge

Postby BWD » Thu Sep 13, 2018 5:35 pm

My first few boards I didn't worry about this, used cheapest decent glass and little carbon, but now there is a lot more specialized fabric available and affordable.
But still not $3-5/yard.
Then carbon was super expensive with gulf war and boeing production ramp up... ...yeah i'm getting old(er).


Return to “Board Builders”

Who is online

Users browsing this forum: Bing [Bot] and 1 guest

cron