A Three Year Project: Slalom C1 to the latest specs

[Bob P]

Tried out the seat at 2" forward, and didn't like it at all. Then I compromised and move the seat back to 1" forward of it's original position. Love it! Here's the video:

https://www.youtube.com/watch?v=3phvpLK ... o_WDJogiGw" onclick="window.open(this.href);return false;

Besides the flatwater work shown, I paddle upstream about a half mile into some more interesting current. Not exactly whitewater, but there are some actual features. The boat worked really well there.

[clt_capt]

Looks a lot better to me. The tail doesn't seem to be dragging as much, and it doesn't look like it hurt you at all getting the stern to catch to pivot.

[Matt Fritz]

Bob,

Your boat looks great. It must feel great to paddle a boat of your own design.

Would you mind sharing your layup, how much epoxy you used and any tricks you learned? Also, which areas you added extra material.

I too am building a slalom C1 and am just to the point of laying it up. I think I want to use all carbon and west system epoxy.

Thanks,
Matt

[Bob P]

The Layup:
Deck - 5 oz Carbon, Spheretex, 5 oz Carbon. It came out about 5 lbs with the coaming
Hull - 3-4 x 5 oz Carbon, 1 x 6 oz Carbon/Kevlar with bow and stern reinforcements. I decided not to core the hull because I have had bad experiences with water soaking into the core through a small rip. About 10 lbs

Add seams, seat, and straps.

20 lbs ready to paddle. Very stiff.

I didn't keep track of the amount of epoxy, since my first hull layup was a disaster. I used an infusion epoxy from IllStreet. "Only" about $110/gallon.

I made every mistake in the book, and some not listed. Infusing such a large part requires everything to work together. Total materials in the boat (including vacuum-bagging stuff) were about $800, but I spent more than that. The vacuum pump alone was $200+. The mold had about $300 worth of material in it. All cheap stuff from work. I have just about enough material left over for another boat. When it gets warmer (and my basement gets above 50F), I'm going to do another boat, same deck, fiberglass/Kevlar hull.

[Matt Fritz]

Thanks for the info Bob.

Are you happy with the stiffness and durability of your hull? Does "3-4 x 5 oz Carbon" mean 3 layer of carbon in some areas and 4 layers in other areas?

Right now I am planning to do 5 layers of all carbon with no coring for both hull and deck with hand layup (no vacuum bagging). I also plan to buy 2 gallons of epoxy. What do you think?

Matt

[JimW]

Have you hand laid carbon before?

If not practise some first - just make some flat panels on a board, or a boat cradle or something.
When you wet glass it turns transparent when you get enough resin into it, when you wet carbon it stays black and shiny, there is no visual guide to tell you if it is wet out or not. It is therefore worthwhile getting in some practise runs to get a feel for how much resin and how much rolling it needed to thoroughly wet through the carbon.

I'm afraid I can't really guide you in terms of resin quantities, but 2 gallons must weigh about 10kg which is more than Bobs entire boat. By weight you probably want to be around 50/50 carbon/epoxy to get near max strength so 2 gallons should be enough allowing for practise, waste and so on. You will be throwing the stuff away with roller refills and washing it out of brushes not to mention the stuff you never quite scrape out around the edges of the roller trays Your peel ply will remove a little and if it soaks into the breather some will go there too. Yep, I reckon 2 gallons is probably about right, last thing you want is to run out just before you are ready to vac bag!

Good luck!

[Bob P]

Thanks for the info Bob.

Are you happy with the stiffness and durability of your hull? Does "3-4 x 5 oz Carbon" mean 3 layer of carbon in some areas and 4 layers in other areas?

Yes, plus the final carbon/kevlar layer. The boat is really stiff. I also used some polyester cloth as a "core" in the flattest areas. I put in a couple of cross-braces (~2" wide, core/carbon) in the hull, in front of and behind the cockpit.

Right now I am planning to do 5 layers of all carbon with no coring for both hull and deck with hand layup (no vacuum bagging). I also plan to buy 2 gallons of epoxy. What do you think?

5 layers (assuming 5 oz material) is overkill for the deck. If there are big flat areas, use core material. The deck doesn't encounter scrapes, so the core will never be exposed.

As has been said, it's really hard to properly saturate cloth from one side, and if you wet out the mold before you lay in the material, have at least two people to lay in the material. Otherwise, it will be a disaster. A tightly-woven glass is will hold its shape better, but carbon can end up a horrible mess. Ask me how I know...

[Matt Fritz]

Bob and Jim,

Thanks for the info.

I have never layed up a boat but have done a couple of pairs of carbon knee cups. So I have a little experience.

For my boat, I'm trying a lost foam technique. I've carved a foam plug and covered it in packing tape. Next I plan to glass to plug with carbon fiber, hull and then deck, like the surf board guys do. Then I'll cut out the cockpit and either dissolve out the foam or carve it out by had. This way I don't have to build a mold or do inside seams and it seems faster. I may put an outside seam on the stern depending on how well I can get the carbon fiber to wrap around. I don't think vacuum bagging will work as I don't think the foam plug would stand up to it.

I do expect to have to do some filling and sanding of the outside when done.

Because of this technique, I don't think I can use any core materials. I think it would make bumps in the outside. If the area under the cockpit is not stiff enough, I plan to add some ribs to the inside after I've removed the foam.

This may end in a big mess, but right now I'm excited and encouraged because I really like the way the foam plug turned out.

I've ordered my carbon fiber and epoxy and starting to think of how to do the layup. Below is what I'm thinking.

- cut out and rollup all 5 layers of carbon fiber for both deck and hull
- coat hull with epoxy
- place 1st layer of carbon on hull
- dump epoxy on top of carbon and work around to get it all wet out
- squeegee excess epoxy back into cup
- place 2nd - 5th layer of carbon on hull and repeat above
- on all layers try to make fabric wrap around edge for at least 1 inch overlap with deck
- allow hull to cure
- sand edges of hull carbon fiber
- repeat above for 5 layers on deck

Any comments on the how to do the layup of the whole lost foam idea?

Matt

[Matt Fritz]

And here is my plug.

[Bob P]

If that is regulation length (3.5M), it doesn't look like there's much stern volume. You may even lose some speed because the bow is going to be float high unless you're really "cab-forward". It will be interesting to see how it paddles.

I've never used your "lost faom" technique to build a boat, even as a one-off, so I can't give you much construction advice. Just be advised that carbon-fiber (and epoxy) dust is nasty stuff. Wear full protection when sanding.

[Matt Fritz]

Yes, a bad design is definitely a risk.

The plug is 3.65m, so it is a little longer than the minimum length of 3.5m. It is also extra wide. I'm 6'6" tall and 195lbs and tired of paddling a boat (vajda lizard xl) designed for someone who is 160 lbs. I'm aiming for a lot of stability and easy turning. Also hoping that the length will make up for some of the speed lost due to the extra width.

Matt

[clt_capt]

5 layers of carbon is quite a bit. it will be a pretty tough boat. and a but heavier than typical. A typical race layup would be more like 1 carbon, 2 carbon/kevlar hybrid for the hull and 1 carbon, 1 or 2 Carbon/Kevlar Hybrid.

I think you will also find that carbon will have a rough surface. You may want to consider a layer of 2 oz glass on the outside - and assume that it is sacrificial while you sand and fair to make your mold.

The lost foam method is fine, but I would interleave the layers - rather than all 5 layers of hull then 5 layers of the deck.

If you are just building a plug that you will be tuning to make a mold from, I would suggest using glass - a lot cheaper, a lot easier to fair out.

[Matt Fritz]

Maybe should just do 4 layers on the deck?

I like the idea of the outer layer off glass to sand away. Do you think just a thin coat of epoxy could serve the same purpose?

I can't figure out how to interleaved layers from the deck and hull. If I do one for the hull and turn it over to do one for the deck I think the hull one will fall off.

I think I will try to stair step the edge of the layers.

I don't really want to do a mold. I just want one boat.

[clt_capt]

Unless you put some type of sealer and release agent on the plug, I doubt it will fall off when you flip - unless you are trying to do it wet. I would probably do 2 layers, let it set, flip, 2 layers on the deck, let cure, and repeat until all layers are on. A 5/4 hand laid boat is probably going to go 25 - 30 lbs before outfitting.

Yes you can use resin as your sanding surface. it will add very little strength, just weight.