Boat building Q-Epoxy vs. vinylester

[Sir Adam]

It looks like I may finally build "my" Maven this weekend, if a few things work out.

Right now I'm planning on using Vinylester resin for the halves, and do the seams and cockpit rim with West systems epoxy.

Are there any major pros for doing the entire boat in epoxy? I know it is stiffer, but to be honest a little flex isn't a bad thing. (I don't want it to "crack" now do I ).

The pros I see for vinylester are workability (easier to wet the cloth out), and time (kicks off faster...which is good when you want to build the halves in a weekend, including graphics).

The layup I plan (with selective reinforcements in a few areas):

Hull S,S, C, CK, S
Deck S, C, CK, S

S being S-glass, C being Carbon, CK being Carbon Kevlar

Inside seam of Kevlar (normal), outside seam of kevlar (bias tape).

I'm planning on two layers for each (inside and outside), though with the weight of the bias tape (15oz?) I'm tempted to go with a single layer. Any opinions on that one as well?

I know there are some strong opinions for and against the use of some of these matierals in a boat of this type. This is what I've decided to try...this time .

[Marko]

HI


I do all my prototypes with vinyl these days. I have only good things to say working with vinyl. Price is great, less than 8 € kg inc. hardeners and accelrators. It is cheap. I generally use derakane 470-11. very easy to laminate and you can laminate with minimal crew even all alone. good stiffness and wear properties.

I would recomend using longest possible work time (as little accelerator as possible) and to work in cool enough room 18-19 deg is optimal to me. For seam have special fast resin made with plenty accelerator with work time of 5-15 minutes.

I found vinyl very easy to laminate and it is very easy to do whole laminate extremely fast and wet. Since resin is thin only minimal amount exxess resin is left and no vacuum is needed for perfect laminate. Laminates tend to have too little resin.

I have used in mold seeming for best results. prosedure is as follows. Its is really busy but reselts are good. seam are done mainly wet to wet for best stick. minimal sanding is needed and very little to no cutting at all.

Remeber to do rim first. Place gelgoat and let dry 6 hours. laminate deck and bottom all in once and as fast as possible.

1. after laminating deck and bottom, let dry 3 hours and cut exess fibers that go over mold sides with sharp knife (do not laminate kevlar over edges)

2. let dry about 10 hours

3. bolt on deck and check straightness

4. Leaning left side, laminate inner left seam with fast resin and let dry 30 min resin will seal seam 100%

5. Leaning right side, laminate rigt inner seam with fast resin and let dry 30 min.

6. place an temperature regulated electric heater and set it to 30-45 deg C inside the mold and let dry 6-10 hours.

7. open mold and release

8. place rim on top and seam it and add kevlar to laminate outer seam

9. place kayak to sauna or other hot place and heat as you like. for stiffness use hot and short for flex less temp and more time. for wave freestyler I use 80 deg C overnight and they are rockhard (no rocks please).


ALso used HERON 970... much more flexible result but not bad at all.

[Marko]

BTW: I have to say that I have had a great results using multiaxial glass in inside seams. If someone is in to saving.

Same material works pretty well in hulls too. Much cheaper than thin wowen S glass and You can run a single clotch through slalom hull at optimal 60/60 -75/75 deg angle.

I used 2 ck 170 g, Multiaxial 600g, 2 ck 170 g in my freestyler and it so stiff you can jump on the hull withoutflex.

[John Coraor]

All my whole boat layups (as opposed to repairs) have been in vinylester so I can't offer any advice there.

As to the layers, in my experience a 5/4 layup is more typical of an "expedition" weight layup, with a 4/3 being more of the standard weight. You may want the extra beefiness, although, with the carbon layers, it is already going to be pretty stiff.

Also, John Sweet always advised having the kevlar on the innermost layer rather than on the outside or sandwiched in the middle, particularly if you only have one layer with kevlar. It's my understanding that kevlar is strongest under tension as opposed to compression, which is why it should be used for inner layers in preference to outer layers. Encapsulating the more brittle glass layers with tougher and more flexible synthetic layers on both inside and outside was the basis of the old Penn State layup (originally nylon encapsulating E-glass, later kevlar on the inside and nylon, polyester or sometimes S-glass on the outside).

There you go; free advice and worth every penny you've paid for it!!

John

[Sir Adam]

Thank you for your quick replies!

You both bring up some great points!

The layering I was considering was based on what Murky and PS use. Originally I was thinking a 5/6 layup rather than a 4/5. A lot of the Angst boats are 6/8, albeit with polyester rather than kevlar.

My plan was to have the brittle layers outside (s glass) for abrasion resistance, and a single layer inside for ease of outfitting and "comfort".

I will seriously consider either dropping the single layer of inside s glass, or replacing it with kevlar.

Therefore, the boat might be as follows (outside to inside for each layer-S glass always on the outside:

Hull-S,S,C,CK,K
Deck-S,C,CK,K


Thoughts?

[edg]

Adam- Great looking boat! I once approached Victor at Class V with the idea of building a wildwater boat, and he had some interesting thoughts. I had always heard that epoxy was "stronger" but Victor pointed out that vynlester is lighter, so for a boat of a given weight (like a race boat) you can use more reinforcement with vynlester, thereby getting a boat that is as strong. He also pointed out that either Noah or Phoenix had used vynlester, and their boats were legendary for strenghth and durability. I came away convinced. Good luck (and I'm now slipping away to see how my skeg is setting up)...edg

[Rumplestiltskin]

I preferred to use epoxy resin when doing hand lay-up during winter. By using epoxy, I could get more time to control the resin content of each layer (the squeegee work) before the mix went off and resin removable was ended.

I found it easier to control the air temperature in the shop (using heat lamps and electric space heaters) after the cloth was properly saturated, etc., with epoxy, rather than trying to adjust heat sources while still working the excess resin out of a vinyl ester part.

With vinyl ester, I also became easily frustrated counting out drops of MEKP from a syringe for each resin batch that was dependent upon the variable air temp in the shop. With open doors and exhaust fans in winter, keeping the frustration level low while laying up was real important for me while building!

While Davey and John are probably the best people to ask about what lay-up to use in your boat, I found focusing on total weight per square yard to be a good idea. I have never built a squirt boat, but would guess that subsurface water pressures would call for a much thicker composite in both the deck and hull than for a cruiser or race boat. If a 30 ounce deck and a 40 ounce hull are good for racing, and a 40 ounce deck and a 50 ounce hull are good for cruising, then wouldn't a 50 ounce deck and 60 or 70 ounce hull be better for squirting?

The old 3/4 or 4/5 layer composites were based on using 10 ounce cloth (e-glass) for each layer. When you substitute a 5 ounce Kevlar layer for a 10 ounce eglass, you achieve a weight reduction without losing "strength" because Kevlar is (in certain ways) a stronger material. But the thickness of the laminate is also reduced.

So, generally, you have to be careful when using synthetics (in lieu of glass layers) to assure that you maintain enough material to give a strong, stiff composite.

Some of the more recent editions of Walbridge's manual have a summary of Chip Q's work on which lay-ups work best under controlled (lab) conditions. Basically, it was a combination of Sglass and Kevlar that made the strongest boat. Put the Sglass on the outside and the Kevlar on the inside. Use plenty of each until you get the weight you want in each part.

Using carbon adds stiffness to the laminate. So does using additional layers of material, particularly if those layers are Sglass or Kevlar. So, I say if you want a stiffer boat, add layers, not carbon. The weight savings purchased with use of carbon fibers are relatively expensive, I think.

[ClassFive Boatworks]

Hello,, here's a few tips I think will help. Epoxy or a good Vinylester ( which is epoxy based) will work fine. I only use epoxy in expedition layups. If your using vinylester besure to use no less than 1% by weight of catalyst. Pigment at 6% by weight max.. I noticed you have carbon in the middle of your layup for the hull.. Its natural stiffness is nullified there.. It needs to be at the out side for max effect.. like C,S,S,K,CK...same idea for the deck. If your hand laying it should be stiff enough.. If your bagging,, you'll definitely need a core of some type.. C,S,S,core,K,CK .. also remember , If your bagging, the resin of either system will kick off quicker. Here's my scoop on seams.. The best seams should reflect the laup of the boat.. for example in your case, glass/kevlar/glass- inside and glass/kevlar outside.. epoxy only for the seams for max adhesion . Cheers

[Sir Adam]

Thank you all for your comments! I think I'll be adjusting the layering a bit....

I'll stick with vinyl ester too-mainly as the folks helping me out work with it (and C and K) the other 5 days of the week building ultralight canoes and have things really dialed in for working with it in their shop.

I will not be bagging this boat. In the future I may try and get into it, but that's a few years off I think.

I suspect my inner-most layer will be Kevlar, though I may leave my outer-most layer S glass for abraision resistance more than anything else (it will be without a gel-coat, or pigment for that matter...just a bit of metal flake, and of course the carbon....).

I'm assuming the big concern with metal flake is NOT to overdo it, as it would create a week layer in the boat (as I'm not putting it in a gel-coat layer outside the hull)

[Marko]

HI

I need to warn about carbon... Corbon tends to laminate dry. it sucks resin in a funny way compared to CK kind of slow. ... do not leave it dry... it happened to me too many times...

I use 1000-1200 g / m2 of fibers for freestylers that do take same punnisment as squirts...

[Sir Adam]

Thank you for the advice on the Carbon. The folks helping me out build carbon boats all day long (all hand laid, and not vacuum bagged). If it wasn't for that I wouldn't even consider it as I know how difficult it can be to work with!

Right now I'm thinking of the inside layer being Kevlar, with the exception in the cockpit area where I'll add another layer of glass to ease outfitting.

Any reason not to do this? Is Kevlar actually a better layer to outfit too (I worry about fraid fibers...)

[RodeoClown]

There's actually a very good reason for not doing that. By now, you should have been around fiberglass enough to know what it feels like in your skin. If your inner layer is glass, over time the resin will wear and break down a little bit, so you'll have glass fibers sticking out. So keep your last layer as kevlar (or polyester).

Jeremy

[John Coraor]

I've never had a problem with outfitting on top of an inner layer of Kevlar. I've always viewed the fraying as a plus. If the layer I'm adhering to is frayed then that means I'm going to get a very good bond between that layer and the layers I use for outfitting.

Regarding your reference about using glass instead of kevlar around the cockpit, it wasn't clear if that was glass replacing kevlar or extra glass reinforcement on top of the kevlar in that area. If the former O.K., although I'm not sure why that would be preferable (see above). If the latter, keep in mind that layup of the cockpit rim is going to add 4-6 layers all around the cockpit, which will already make this area the stiffest part of the entire boat.

John

[Sir Adam]

Thanks Jeremy and John...

I am rather familiar with the "old fuzzy glass boat syndrome" due to my eclectic collection of boats.... I usually get around it with some well-placed 1/8" minicell, neoprene foam, or "skins" from minicell batts. I should have phrased my question a bit differently, however John answered what I was looking for-how well Kevlar works as an internal layer. Resin will wear off of kevlar too, though, and I'm curious about kevlar apprasions versus glass ones. I suspect they're not as bad, but any real-life experiences are welcome!

I flipped through the excellent Walbridge boatbuilding manual again last night, focussing on the layup layers and the laminate strength and deformation work contained in it (mine is the 5th edition, from the early '80's). As of now, I am planning on modifying the layup a bit, still keeping the outer layer of S-glass (again, two on the hull for abrasion resistance), then Carbon (for strength and the look of the fiber...I've always wanted a carbon boat ), then either two layers of kevlar or a layer of KC then K.

I'll keep everyone post on the progress, though not in as much detail this time

[Marko]

Hi

I have had best inside of the boat made out of thin 90 g-120 s.-glass. It is operfectly smooth and forms a nice skin to glue padding and also works fine for laminating additinal Kneecups because it is aesy to sand rough. Kevlar is large steaming pile of dog doo to sand due freing and seams stick out guite bad, freyed seam do stick well but unwanted freing should be avoided.

Also think about these 2 things. Carbon in center is stifnesswise partially nullified as pointed aerlier, it has also week wear resistance. Kevlar is soft but has a good wear resistance.

->
I would place kevlar outside and carbon close to inside and cheapest average material in center as for core. I Could also use corematerial for stiffness. If you want to use carbon for looks protect it with thin s- glass or even Diolen.

Stability of your laminate is very important. When bending C G K laminate to max. outside will crack first and K G C will do opposite but I have experienced That in kayak the failures rather compress from kevlar side. My old slalom had kevlar outter and outter shell was cracking too easy. A thin glass on top fixed it.

When doing a kayak that has to be stabily lamnnated look for POlo kayak layups or in doupt use solid Carbon-Kevlar. C-K is fairly cheap compared C or K alone

Earlier you can do the seams better they will stick. I try to do em while resin is still sticky feeling and it is a must to do before final heat treatment. Remember that heat treatment can douple your stiffness if done right ... see resin manufacturer specifications for reference. Using kevalr on seems is best option for sure. A thin glass on top of seamtape joint will help with finish aand if cut is at the end of boat you can douple the strenght there too ...


just my 2 cents ...

MH