KevBoo SUP

General Discussion
1

Don’t ask me why or try to argue the merits, it is what it is…I blame Durbs…

1lb density EPS from Ken…a stringerless 10’6" from his 11’ SUP blank

http://segwaycomposites.com/AB110PLB.gif

8" 5oz Kevlar Tape from Fiberglass Supply

http://fiberglasssupply.com/Product_Catalog/Reinforcements/Carbon_and_Kevlar/carbon_and_kevlar.html

set it up on the board, taped first and then used the plastic wrap as a place holder.

identified the location for our wedge cuts and set up a nice way to line everything up and get it

spliced.

once it’s dry fitted, we pull it back, working on one half of the board at a time.

when it’s wet out and things are in their right place, we wrap the board with the stretch wrap

plastic.

once it’s all set up, we put it in the bag on loooow pressure for a few hours until our control cup

of epoxy is set hard.

pop it out and do the next side

the kevlar was much easier to work with than expected…having two sets of hands was a must.

it really stiffens up the board in this early phase with more yet to come. I used about 20oz of resin

for about 8 yards of tape.

the stretch film was useful to keep the tape in place so we could work in sections (the masking

tape was mostly useless for this purpose), it allows you to get a pretty good finish right out of

the bag if layed down cleanly and makes slipping it in to the vac bag effortless…no shifting or

scrunching.

next phase…bamboo.

deck will get bamboo scraps layed inside the border of the kevlar and then

a second ply that will overlap the kevlar on the deck trimmed so there will

be no need for a pinline on the deck…this will also give me the additional

stiffness I seek in the board as well as a tough surface for standing.

the bottom will get a single layer of bamboo set inside the border of the

kevlar and likely pinlined (wide)

this will receive the ProBox double fin formula as well.

2

afoaf, I’m trying to understand the stretch wrap procedure. It looks like you first stretch wrap the middle bit during dry fitting. So I’m guessing you then wet out either side of that which glues the kevlar in place, then remove the stretch wrap, wet out the middle bit. Then before bagging do a second stretch wrap over the entire board? have I understood correctly?

I like the idea of the kevlar rails, you will get the perimeter stringer effect with the added bonus of increased ding resistance to the rails.

3

Kevlar? You afraid people are going to start shooting at you because you’re on a SUP? :wink:

I don’t know about now, but back in the day, at the boatbuilder, we did a lot of kevlar stuff and one thing I remember was we had to religiously protect it from exposure to sunlight because, as I understood, it would break down rapidly when exposed to sunlight. Maybe someone else with more experience here can weigh in on that matter. Of course, boats are exposed to the sun 24/7…oh wait, that’s 12/7…

Also, I remember sanding the stuff was a beeotch. It would fray and get all fuzzy. Let us know how yours goes.

4

Mr. J, You’re correct.

We used the stretch wrap to hold the dry fitting in place.

It sat on one side of the halfway point.

we marked our layout with pencil so that when we folded back to wet out

the foam we could roll it back in place. the cloth gets wet out (dabbing) and

then brushed tight.

once wet out, we stretch wrap that side…part of the reason, as lillibel points

out, was to minimize the amount of sanding necessary…we wanted to keep

the kevlar low and tight…the wrap helps in that tricky transition to bag.

5

On my CF rail compsand, I rolled up the CF tape, put it in a zip-lock baggie with slow RR, worked it into the cloth and then squeezed it out and unrolled it onto the rails. Looks like your method worked also.

6

that’s a really clever idea.

the kevlar definitely doesn’t seem to want to drink up the resin so much as we sort of ‘pressed’ it in

with a dabbing motion of the brushes.

I’m working on fitting my bamboo scraps for the first ply of bamboo on the deck this week…stay tuned.

7

Anybody ever seen a cast of fiberglass wrapped around a broken arm? Anybody seen this website on rolling your own with a wrap of nylon material?

8

afoaf, just after I wrote about the kevlar providing stiffness I thought to myself maybe I hadn’t got that right and was mixing it up with carbon, so I did a google and found out it is stiffer than glass and the info also said what lillibel said about sunlight degradation. Its meant to have really good impact resistance too. I knew a boardbuilder who told me about the fluffing sanding problems.

However as you said the vacuum bag presses everything very flat and then you are going to glass over it so should avoid the fluffing. Pressing laps flat is one reason why I liked the bag.

A question I have is how well did the cling film release? I remember when I used peel ply over laps on a regular lam it did get caught in some of the lap cuts a little, but being a strong fabric I could pull the peel ply away, so did you get any catching with the cling film?

also the cling film would leave a smooth surface, do you do any prep to get the lam to stick to the kevlar?

9
Quote:
afoaf, just after I wrote about the kevlar providing stiffness I thought to myself maybe I hadn't got that right and was mixing it up with carbon, so I did a google and found out it is stiffer than glass and the info also said what lillibel said about sunlight degradation. Its meant to have really good impact resistance too. I knew a boardbuilder who told me about the fluffing sanding problems.

However as you said the vacuum bag presses everything very flat and then you are going to glass over it so should avoid the fluffing. Pressing laps flat is one reason why I liked the bag.

A question I have is how well did the cling film release? I remember when I used peel ply over laps on a regular lam it did get caught in some of the lap cuts a little, but being a strong fabric I could pull the peel ply away, so did you get any catching with the cling film?

also the cling film would leave a smooth surface, do you do any prep to get the lam to stick to the kevlar?

So I was not just having a nearly senior moment…

My recollection is that if you hit the weave the kevlar would look like the fuzzy part of velcro. They actually made one board with kevlar while I was at Dencho Marine, but they faired it out with microballoons, primered it and then painted it with opaque polyurethane (it was metallic gun metal grey!).

Afoaf, if I were you I would take a test piece and sand it until you hit the weave. If it fluffs up as bad as I remember you can then take that into consideration with prepping your board.

Another thing floating around my nearly senior mind was an article explaining the various engineering properties of Kevlar vs. carbon vs s-glass vs e-glass. There was reason why sailboat masts, rudders and rudder posts are carbon (stiffness and flex return). Kevlar is mostly limited to use in the front third of the boat, under the waterline, a so called crash pad (impact resistance).

10

llilibel is correct on the sanding and UV degradation. Kevlar cannot be sanded AT ALL, in a surfboard context.

It also must be shielded from UV. We talked about this on the WMD compsand thread. Some type of opaque

covering (paint or other) should go on those rails, the UV ‘‘shielding’’ from resin won’t be sufficient.

A fun project and intersting combo of materials, nonetheless. So this is how afoaf and durbs are spending the holidays,

doing evil composites research in the garage? It looks like you’re having fun, keep up the good work!

11

the stretch film I used is that clingy packing wrap you get from Home Depot or Harbor Freight.

it says the only thing it sticks to is itself…it releases very well from the epoxy once it’s cured,

but you are correct…if you get a funny pinch it can get stuck…that stuff should work itself

out when I rough sand the kevlar.

the goal is to not hit the weave…just remove some of the bumps and creases that arose and

then go over it with a few layers of the the blue RR and some 4oz cloth.

perhaps I should just paint the rails…I had considered an opaque tint to overcome the yellow.

I guess I’ll have to think about that.

12

KevBoo - GOT IT, wow I am a loser…

Nice work Tyler, its lookin good, im glad that you can blame this mad science on me. How was cutting the kevlar? Ive been told you need serrated scissors to cut it.

I’ll be sure to bring my oozie when you take that out so we can test its true durability.

Im bummed I am not around to participate in this.

13

yeah, MikeD is giving you too much credit…

Durbs convinced me to forgo a stringer (or two) in the board in favor of taped rails…and, further, to do Kevlar instead of CF.

once I had all the materials assembled, he had already gotten out of Dodge, leaving me to try to sort this out solo.

fortunately, my younger brother is getting a degree in plastics that has exposed him to a lot of these materials academically,

plus he works for cheap (beer) and so we had a go at it after a bottle of wine and some dinner table composite trash talk.

serrated scissors (pinking shears) were absolutely worthless.

didn’t cut worth a damn.

still have to figure out if I can return the things.

Fortunately, I also bought a couple of pairs of Fiskars shears from Joann Fabrics…they were having a 50% off sale on all scissors

so I stocked up assuming at least one pair would be a throw away.

There were two cuts to get the tape to length and 4 wedges put in to each piece, plus the trimming…by the end you could

feel the shears working less effectively; They’ll still be a great pair of fiberglass shears though and I doubt I’ll use this stuff

again.

lillibel, you’d love this project, I’m basically utilizing all of my fiberglass and bamboo offcuts from previous projects on this

monstrosity…the 1 lb density EPS is so soft and the board still so light that I think I have enough room to go nuts with

the skins.

14

Sorry I got the ‘‘helper’’ credit wrong, it figures durbs would talk you into this and then run off before the dirty

work started. Thank goodness for little brothers and beer, right?

Re cutting the Kevlar; you’re supposed to get the special ‘‘Kevlar shears’’, ordinary serrateds or other scissors just

won’t do. And they’re available for the low, low price of a couple hundred dollars at your neighborhood aerospace

store.

You’ll probably find that doing the rails was the hardest part of the whole project. All downhill from here. Keep it tight…

15

I wish that is how i was spending my holidays… but i have relocated 100 mi north. Instead I am spending my holidays getting my home-made vac system up and running. The electronics are really finicky, but I think my dad and I are getting it back into operation.

Edit:

Got the vac electronics in shape… test run this afternoon maybe. South Bay Labs, Goleta Division is about to open up.

16

one word: BLEEDER VALVE

17
Quote:

one word: BLEEDER VALVE

Two words?

I will be buying one of those pumps in the near future, I think the feedback system we set up really only works past -10inHg which is fine for the higher density stuff i will be using for now. Regardless, I have enjoyed the trial and error process of building a controllable vac pump from a refrigerator compressor… provided some quality father-son time too.

18

Little brother? For a second there when it became obvious that Durbs was not the one lending an extra pair of hands I started thinking, “How’s he getting his six month old son to hold that plastic??”

You get my vote for Sway’s mad scientist of the year award. Lots of experimentation going on there. I’m still working on how to pickle fish…

19

Wow now thats a project! You are a glutton for punishment. I seams like your already past the rails, but here are a few tricks I learned the hard way.

After ruining a few pairs of expensive shears I found these http://www.acp-composites.com/acp-ta.htm for Kevlar shears. The plastic handled ones are only $26. Cuts it like paper.

If your Kevlar has stitched sides on the 8" tape then I’d roll it on the board dry to get the length. Take it off and wet it out on a wet-out table. Once you get it all saturated roll it up and then roll back onto the board. Do your relief cuts if needed as you roll it out. A wet out table can be anything flat, mine is a 2x5 piece of mdf that I cover with clear plastic. I staple it in place and rip it off after each use. I’ve also seen others take the tape put it in a coffee can all rolled up to get it fully saturated then literaly squeeze it like a rag to get every drop of resin out of the cloth, then apply.

If you sealed the blank before you started it should have a light crust that is useful for a bagging trick. Once you get the Kevlar applied on the rail take a perforated film, saran wrap, bleeder (rayon), etc. and staple it directly onto the blank over the saturated cloth. The crust helps the staple stick. You don’t need to use very many staples, only enough to hold the material down onto the saturated Kevlar. That way it will go into the bag with no problems. The staple dents will be covered by your deck and or bottom and can be filled with your sealing bog.

Another simpler yet messier approach is to lay a layer of .58 oz. veil http://www.acp-composites.com/acp-fc.htm over the Kevlar. Smooth it down with your hand until it saturates and sticks to the cloth and board. It weighs nothing and act like a sticky spider web to hold things in place. For being only a 1/2 ounce it is very strong and won’t tear or separate once saturated.

20

Don’t go nuts with the skins. Stick to your game plan. You still have a lot of real estate to fill with wood, cloth, and epoxy.

The guy down the street from me makes SUP’s, and he’s really good at it, and they are eps/epoxy and still weigh heaps.