Need help with CF/Kevlar hybrid Paddle Board

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#1

Alright, so I’m new to the sight and I am a novice with composite parts fabrication. I hope to gain a little more information and knowledge before D-day when I take the grand worth of materials I have purchased and either mess it all up, or put it all together.

I am a helicopter mechanic in the USMC and most glass work I do is patches and repairs, although I have been in the books so to speak, trying to learn as much as I can to produce this Stand Up Paddleboard. There are other surfboard forums I have researched, but they don’t seem to really grasp certain things I want to incorporate into my board. So here is my process;

The core will be EPS pre shaped and essentially ready to glass at 11’ long 30" wide and 4"1/4 thick. I want to do 2 layers of fiberglass on top 1 on bottom (3.4 oz S glass satin weave), 1 layer of carbon fiber on top of that (5oz plain weave 3k), after that I want to try and sandwich some 2mm coremat soft core material before one layer of a twill weave 3k CF/Kevlar hybrid. My theory with the soft core is that it will help with impacts in between the carbon fiber and CF/Kevlar. I will be using a UV resistant epoxy resin with additive F for aid in sanding and I have just heard it is good stuff so.

NOTE: I am not exactly sure if this soft core material will actually aid in impacts. Since my rolls of material are 50" wide. I was going to take 12" or so from the sides and do a couple of miniatures to see how the turn out will be. Beat them up with a hammer and feel out which lay up is best. I inserted a pic of the soft core stuff.

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The tricky part is going to be vacuum bagging the whole thing. I want to try and get it bagged in one go. Top and bottom. All layers. I am of course not sure if this will even work. Nobody in the surf board world I know has seemed to perfected it and I am not sure how the soft core will work in the bagging process. Either way here is what I plan and your warnings cautions and advisories would be great.

I have a 7.5 CFM pump. I THINK it should work. With some slow curing epoxy I think I can lay up the bottom in 30 min before it hardens in the mixing bucket. And then the top with another batch. Any way. Lay up the bottom as described previously. Lay down the peel ply, bleeder, and film. Some how flip it over and as one person is laying the tacky tape on the bottom halves film, I’ll start laying the top of the board I want the lap of material to lap on the rails of the board in the center. Work the epoxy in same as bottom with squeegees and rollers. Lay the the peel ply bleeder and film. I have two bag connectors I was going to do one at the top right Conner and another at the bottom left. I have hose splitter and 25 ft of hose.

I would love for this method to work but I realize it will be tricky to say the least. I know I might have to do one half first then the other. I don’t know if the tacky tape will work well enough on the bottom of the polystyrene blank. I am also worried the the suction of the pump will damage the eps foam.

I want to finish with uni directional CF tape running around the rails of the entire board, essentially hiding the lap line and enforcing the rails from damage.

Any way that is the just of it. Please go easy on me. I would really like to not learn by error on this one since error in this world=money. However I am going to go for it and I do understand the price of this is a bit ridiculous.

Few questions I have

Is 2 layers of fiberglass 1 layer of CF and one layer of CF Kevlar enough for let’s say a 200lb man standing on it all day. Or will it be too much

Has any one had any experience with this soft core material. I got it from elite motoring on eBay. My goal is to increase impact resistance.

I seem to feel like I’ll have to bag the fiber glass layers and the CF. Let it cure then add the SC mat and Cf Kev. Does anyone know if it’ll work the way I described.

Thanks If you actually read that whole post

#2

One more question. For the fun box I have a diamond coated router it. Will this work on the Kevlar

#3

One more question. For the fun box I have a diamond coated router it. Will this work on the Kevlar

#4

So just to confirm, EPS blank, 2 or 1 layers of fibreglass, 1 layer carbon then 5mm coremat then 1 layer carbon?
So to the outer world, theres 1 layer of carbon fibre before the Coremat? That wont be any good, will be way to light and hitting a jellyfish is likely to puncture it :slight_smile:

So, no in this format the coremat def wont help with impacts. Impacts would be resisted by just adding the kevlar in alone.

Vac bagging could be done in one go but is likely to give you wrinkles on the surface (particularly as its a first blast) as you’re effectively vac bagging a tube

#5

Alright. So should I cut out the core Matt. The way I understand it, which is probably incorrect, the Kevlar disperses the kinetic energy throughout the skin. If it was just carbon fiber under the Kevlar, would the energy just transfer to the CF? Essentially cracking it?

Can you tell me what lay up you would do to maximize strength/impact resistance?

Yes I foresee the wrinkles as well and I have no idea how I’m going to avoid them. I have strechelon 200 for bagging film. That is about all I can think of.

Can any body tell me if bagging the belly first, letting cure, then bagging the deck last be a smarter move? Would this offer the same strength properties as one go? Doesn’t seem like it would.

#6

The thicker you can make the skins, the more impact resistant it will be so say you had a 10mm layer of fibreglass, that will be more impact resistant than a 1mm layer of fibreglass. By placing just 1 layer of carbon/kevlar or anything else on the outside, the puncture resistance will be low.
I would leave the coremat out if it was me, go with the highest density/stiffest blank you can get away with that can be shaped (eg the EPS) and then put a solid laminate around it. This solid laminate could be fibreglass on the inside and Kevlar/Carbon hybrid on the outside for example.

Im not sure on EPS, Im sure it will be fine but will it collapse under the force of a vacuum bag? Check that first anyway.

If it doesnt, vac bagging in one go will be the best way to do it but yeah there will be wrinkles. And if you’re using a carbon/kevlar outer layer, the wrinkles wont be easy to sand out! Perhaps modify the layers for an extra fibreglass layer on the outside that will be sacrifical for sanding purposes. Male tooling fully encapsulated like this will always be likely to produce wrinkles so sanding will be inevitable

#7

I hear you. I think I’m going to go with one side vacuum bagging at a time. I am sure it’ll happen to but I’d like to minimize wrinkles.

Will two layers of fiber glass one layer of 3k CF and 2 layers of hybrid work? Honestly the only reason I’m puttin the CF under the hybrid is for stiffness and rigidity. I’m sure there is something else I could use that is more cost effective??

#8

From the research I’ve done I don’t think it’s common to vacuum bag SUPs…Most of the guys I’ve seen forgo that step and just squeegee/roll out the excess epoxy just like the standard surfboard process. If it were me I’d run a trial with a 1-foot miniature board using the exact materials and processes you’re planning on using on the real thing…At the very least it’ll save you the $200 in CF if you find an error in your process. It’ll also give you a better finished product and I’m sure you’ll find changes to make to your system. I’d be inclined to lay 1 layer of FG, then coremat, followed by 1 layer of Kevlar and 1 of CF…Depending what weight you’re going for I might consider adding a second layer of CF between coremat and Kevlar.

Sidenote…HMLAs or 53s?

#9

Ha! HMLA 167. Nice guess. I think that is great advice and pretty much what I’m gonna have to do. And I’ll just use the side trimming from the roll I have. It’s 50" and I shouldn’t need more than 40". So.

I know that it definately isn’t SOP for SUPs. But it’s worth a try

#10

I’m no surfboard guy… But my friend owns south coast foam and fibrglass. Biggest blank maker in australia :slight_smile: and supplies blanks for the best riders in the world
I use cork cork for RC gliders , and comparing it to core matt it is 10x better. Much more ding resistant and doesn’t sock up resin so it works out much lighter.

Core cork has been used in lots of composite kayaks and race kayaks and now there are quite a few companies using it to build SUPS and surfboards.
Do some google surf he’s on cork surfboards , plenty of info there.
I think bagging one wouldn’t be that hard , but don’t think it’s worth it. The strechalon you have will be great if you choose to do so.
I’d lay up one side and put a layer of peel ply on it to stop it from sticking to plastic and distorting etc before it under vacuum. Have it sitting on a large rectangle piece of vacuum plastic and once you lay up the 2nd side just fold up and over the board and seal all the edges with no more gaps sealant ( I use it everyday for bagging)
I’ll ask my mate what he recommends for a good lay up :slight_smile:

Tim

Here is a little thread to check out
http://www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Cork-sandwich-construction/?page=2

#11

Dude that’s brilliant. I’ve seen the cork decks. But they’re exposed. Never put the two together. I guess that’s sort of sad since we’re talking about composites, and, well…

Man I’m not going to sleep tonight thanks. If you could ask him that’d be great. People here on the east coast are stingy about what they know. (no offense to anyone)

#12

Let us all know what you end up going with. I’m sure there are others that can benefit from your experience.

Side note: I sit behind a Cobra pilot in class. Flew Yankees and Zulus with all three squadrons at NR but hasn’t been with 167 since 2011

#13

No kidding. That a weird. I’ve been with 167 since 06.

#14

Hi Davenew,

This is an awesome project! I’ve just laid up a surfboard for my son using the more traditional techniques of draping lightweight fibreglass cloth over an EPS foam core to get some practice in before embarking on SUP projects for both myself and my partner. I wanted to use carbon/kevlar as well. I was originally planning on using the traditional surfboard technique, just substituting the fibreglass with carbon/kevlar cloth. So using 2 layers of 188g carbon/kevlar for the top and 4 for the bottom.

I was a little concerned at the quality of the outcome, and after doing some research there are some cool comapanies out there making hollow surfboards out of carbon, with a foam lining top and bottom, similar to your idea with the coremat. I was planning on foregoing any fibreglass and just using the carbon/kevlar cloth, unlike your original plan.

However, after doing my research, I’m seriously contemplating getting a foam core to use as a plug to make a two piece female mold for a carbon/kevlar board. Here’s the link to the company that makes the boards: http://avisosurf.com/TechAdvantage.html There’s a few more out there as well.

Keen to see your progress on this and to see what the far more knowledgeable members have to say! I’ll be starting a thread on my experiment soon to document my success/failure.

#15

Looking forward to seeing how you go. It’s funny you say that because a couple days ago I decided that I’ll be going with a hollow board as well mainly because a shaped blank is 300$!

Atleast the only one I could find around here. So that changes everything. I am trying to figure out now what kind of core material I want to go with for the sandwich panels. Looking for strength and something fairly cheap. As of now I think I’m going make a mold from a 1/4" board and use 4lb mix and pour polyurethane foam.

Kind of hoping someone had a better idea. Because I’m looking at 150$ for 2 12’ foam panels for a sandwich core.

One more question. Why would you use two layers for the top and four for the bottom. My understanding you would want more on top for added strength for the person standing on the deck for hours at a time? Thanks for help.

#16

Yes, the blanks are pricey, huh! Although you could just find a foam supply and buy a sheet and make a hotwire to quickly cut the basic shape, before sanding and shaping proper yourself? Not sure if that would decrease the cost for you at all? I’ve made a hotwire for cutting RC plane wings before out of some metal guitar string, some wood for a frame and a car battery. Not the safest or best way of doing it, but I was a lot younger then!

There is another company that uses an internal rib design on their boards that might be worth a look? http://www.hydroepic.com/techhull.php I was thinking that could be an option. So, use the two female molds to lay up the board, and either use a separate mold to make a rib design, then bond it in before joining the two halves, or maybe using some kind of foam core to place onto the part after you’ve laid it in the mold, then lay up over the foam to produce the rib? This is pushing my limits of composite construction, so some more research on this forum would be required on the best form of attack.

Hopefully somebody has a better idea, as the costs can quickly creep up. Have you decided on fin mounts and fins yet? They can add some cost to, at least over in this part of the world. There’s a couple of guys on this forum that have talked about the process to make your own, so that is an option. I wimped out and bought mine though!

That is an excellent point on the layers on top. I was just basing that off of some of the surfboard fibreglass designs, assuming that the carbon/kevlar would be stronger so even accounting for the increased dimensions of the board it would still work. I’ll have to have a chat to an engineer friend of mine on how best to calculate what is actually required. Maybe a couple of extra layers where you stand would be sufficient? I don’t know. I will have to find out.

#17

Wow. I don’t know paddleboards. But, for almost 20 years I’ve occasionally made a surfboard for myself or a friend. 14 or 15 boards so far, so I’m no expert. However, I know enough to say that you, good friend, are taking on a seeeeeeerious challenge for a first go.

There’s a guy that posts on here and Swaylocks named Dwight. He’s the first person I would try to contact for advice on skinning and bagging a paddleboard.

I didn’t notice what density EPS you’re planning on using, but my gut tells me what you laid out in your initial post is overbuilt. Also, a first-timer trying to bag all those different materials in one go is likely to be a comedy of errors. It’s definitely worthwhile to do some small-scale practice work for every stage of whatever you plan do do.

Corecork is absolutely worth considering. If you’re in the US, Drew Baggett at Inspired Surfboards (St. Augustine, FL) was selling and shipping cut yardage of corecork to hobbyists for some time. Hopefully he still is, cause I want to get some in the forseeable future, and if he isn’t selling it anymore then you pretty much have to buy a full roll.

You’re correct in that no one has really laid out the whole process online, because the only people that know how do do it well are making a living from it and paid some serious dues to work out all the kinks.

Hope you have fun with it. Wish I could be more helpful.

Regards,
Andrew

#18

Is your blank stringerless?

All mine are, so my advice is based on stringerless.

You must vac bag each side separately.

Bottom, 2 layers 4oz S
Top, 3 layers 4oz S, plus single 6oz carbon deck patch, spanning your deck pad zone. Use the deck pad to hide the carbon.

I use a wetout table to prepreg my cloth. You may be more comfortable just pouring the resin on the board instead.

I’d suggest passing on Resin Research epoxy and buying Greenroom epoxy. It’s more idiot proof. RR is temperamental.

#19

Ok. I actually live where green room board shop is located. So that would be easy.

#20

Howzit Dave,

Just thought I’d give you a link that pertains to your project. If you’re considering cork (not that I’m pushing you one way or another) I’d pay attention to everything Charlie says, whether on Sways or the other SUP forums. He’s been an avid proponent of it for a while now.
Attempting to copy and paste link here:

http://www.swaylocks.com/forums/vac-bagging-tips

Later.