Standup Zone Forum
General => The Shape Shack => Topic started by: burchas on November 22, 2018, 09:25:37 AM
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I'm working on a downwind hybrid board 15x27x4.5 @225L
Found a cool way to add stiffness without weight penalty using triangle carbon stringers added into the foam
(hot wire foam cutout added back after the layup) and runs 3/4 length of the board.
Now want to keep the construction fairly light, stiff and cheap but still reasonably impact resistant.
I'm afraid that glass alone will not do the trick. Read some positive stuff about Innegra reinforcements sandwiched
in between the glass layers placed in strategic sections. Also read some negatives about vector net. Trying to avoid
any carbon and bagging for the same reasons.
Target weight is under 25LB (1.5# blank).
Any ideas?
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Starting out with 1.5# is going to make it tougher to stay under 25 lbs. With the big boards you kind of have to stay with 1#.
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Starting out with 1.5# is going to make it tougher to stay under 25 lbs. With the big boards you kind of have to stay with 1#.
Noted. Any words of wisdom about that layup and cost effective alternatives?
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With a hand layup, E and S glass will make a flexy 16' or 18' board. At a minimum you need CF down the rails. I talked with a lot of glassers before glassing mine. The responses where all similar. One layer CF, overlap the rails. Then a sander layer of Veil cloth (2 or 4 oz glass). If you have the money, very light 1K plain or twill weave 3.5 oz.(twill is more). A few pounds more use 3K CF 5.7 oz. plain weave. The 3K is a course fabric, almost like burlap. Those little pockets in the weave of the 3K hold epoxy weight. The only way to reduce that is use 1K CF or V-bag the 3K CF.
https://www.fibreglast.com/product/1K_Plain_Weave_Ultralight_Carbon_Fiber_Fabric_2363/carbon_fiber_all
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That 1K ultra light is just insanely expensive.
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With a hand layup, E and S glass will make a flexy 16' or 18' board...
So considering it's only a 15' and will have the implanted triangle stringer (see cross-section pic)
and both top and bottom carbon stringers if needed. Do still think it's going to be too flexy?
How about vector net just to overlap the rails with above configuration?
That 1K ultra light sure is insanely expensive. I'm trying to keep this one under tight budget.
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Wrap the rails with CF. Put a patch of CF in the main standing area. Do the rest with 4 & 6 oz. S-glass. That little V stinger is not going to do much for stiffness. It would have to extend the full depth of the board to really have a noticeably stiffer board. Us a cassette of high density PU foam or PVC foam at the fin boxes and handle areas. You can use this 3K CF tape / 6" strips. One roll will do a couple of boards.
https://www.fibreglast.com/product/Carbon_Fiber_Tape_597/carbon-fiber-tapes-tow-and-sleeves
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Good to know. Thx!
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If you get a 6" roll of the CF you could add a CF stringer strip on the top and bottom. My friend does this on most of his race boards. It helps reinforce the fin box and handle areas and stiffens the board even more, while adding very little weight or cost.
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TD called it. The rails will get you the stiffness you want.
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Burchas-Looking forward to seeing some build pics!
225 L = 7.95 CF of EPS foam
nominal 1 PCF =7.95 pounds theoretical of foam
nominal 1.5 PCF =11.93 pounds
Here is a glassing schedule thread I remember, started by the Cowboy:
https://www.standupzone.com/forum/index.php/topic,27149.0.html (https://www.standupzone.com/forum/index.php/topic,27149.0.html)
EDIT: adding image of laps. Magenta=stand patch, white=CF, red=layer 1, green=layer 2, cyan=foam
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Good stuff TallDude & jrandy. Very informative.
So if I wanted to squeeze an Innegra layer on the rails for added impact resistance, where would
this layer be on the diagram? Will 2 oz Innegra do the trick?
I've stumbled on this CARBON FIBRE & INNEGRA HYBRID:
https://www.fibreglassshop.co.nz/products/carbonfibreinnegrahybrid?variant=8040308113456
Any experience with this? Can it actually be applied instead of the 2 separate layers (on the rails)?
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The Carbon/Innegra is good way to good as well, but I think sanding the Innegra is similar to sanding Kevlar. PITA. Better suited for a V-bag on rounded rails and laps, but could be done with a hand lay up.
https://youtu.be/wM26QHAVXB4
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Soller Composites has 1K Carbon cloth far far cheaper at USD 50 a yard. Fibre Glast must have made a mistake in pricing.
https://www.sollercomposites.com/Carbon-1K-Fabrics.html
Soller's 6 in tape with tails is far cheaper too.
https://www.sollercomposites.com/Tapes.html#tails
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I see Soller offers biaxial tapes, although 4" is their broadest size. Biaxial would make for very stiff rails.
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I see Soller offers biaxial tapes, although 4" is their broadest size. Biaxial would make for very stiff rails.
Would be helpful if they had it in 6". Their prices are really cheaper by far.
I wonder if there is any difference in quality of materials.
Can't remember where I read about it, saying something to the fact that the Aerospace grade carbon is
far superior to the industry standard. Not sure if that's a myth or an actual fact. Would be helpful once
I'm done with budget prototype boards.