A question for you engineer types. Plywood, the high quality marine grade, has always been a very good material for boat building. Would carbon fiber lends itself to a similar material?

Just asking.

Are you asking; would carbon fiber be better to use than marine plywood, or have the ability to be used in conjunction with plywood or similar material in construction?

Are you thinking of going with regular construction plywood and using carbon fiber/epoxy to strengthen the material?

Does not compute....................

Good quality marine plywood is increasingly difficult to find and increasingly expensive. It's still wood, it still rots.

I would most prefer to find a carbon product and use that in place of plywood. So, I'm looking for carbon sheets, approx. 4' x 8' in some sort of laminate configuration. Carbon/foam sandwich? I'd think 1/4" thickness would be good.

Google is your friend. I found this in about 6 seconds.
http://www.dragonplate.com/
To compare "expensive" plywood/okoume w/ carbon fiber is a stretch. The cost difference would be huge, but you would definitely end up with a better product.

hey Paul ,
I liked your tri build blog. , good looking boat.

I am not sure what you are asking. If you are asking is there a carbon sheet that I can bend into shape like plywood? The answer is sorta. You can't bend hard sheets of carbon like plywood, they break first.

You can heat some carbon/epoxy and bend it into shape. I have some skate boots that you heat to 160F, put 2 layers of socks on, stick your feet in, lace them up, and SCREAM HOT HOT until they cool. They then fit almost perfectly.

You can also use prepreg with a semi rigid core. I have some prepreg with a foam core that bends about like ~1/16" cardboard (spiral notebook cover). The epoxy starts to harden at 140F. For max shelf life, store it at around freezing.

Both of these will be real expensive. I would guess 5-10 times the price of the best plywood and I am not sure how much better they would be.

With the price of carbon so high, I have been playing with ideas. You could probably beat carbon on stiff/durable/impact resistance if you made plywood using epoxy with a kevlar core. I think you could really beat it if you laminated single layers of various wood with epoxy over a mold.

I built test rudder sections using cedar/birch/1.5 oz glass vs solid carbon/epoxy. On a per weight basis the wood was about 20% stiffer and about 100% better for sharp impact. It was also a lot thicker.

Also the wood smelled better and was cheap enough to make a couple of test cases to get it right.

Thanks guys. For my purposes I think the answer is no...or at least not yet.

Check this stuff out: http://www.coosacomposites.com/

That is interesting.

If you need a flat panel, look for surplus aircraft floor and joinerwork pannels. These are available in 3/8, 1/2 and other thicknesses. They are hpneycomb with s-glass or carbon faces. You can find sometimes on EBay. There was a truck load for auction a few years ago and I lost the auction. Was bought by Advanced Vehicle Technology. Still selling it through their store front at www.avt.com I believe. You cannot bend a flat panel appreciably. On the other hand nothing is as stiff and light including anything you can make at home.

There is a French epoxy foam that is weighed carefully, mixed then goes off while making bubbles hopefully filling your mold or space between CF panels perfectly, before hardening.
Paul Bieker uses this in CF hydrofoils that he builds for Bora Gulari and a few others: they are only about $1000 each.
This foam is available in France, UK and Oz and is unavailable in the USA.

I also heard about epoxy foam. Found it in Brazil and would have used to fill my foils, but gave up due to the ridiculous price.

http://www.gurit.com/page.asp?section=00010001002200580001&sectionTitle=SP+Product+Focus%3A+Ampreg+F230+Foaming+Epoxy

SP distributor:
http://www.compositesone.com/


Cheshirecatman

note: top url should be all one string. It didn't copy properly into the message panel.

Pete, there are alot of build methods out there using flat panels but they all have a common problem, that of stitching and taping them together, it simply doesn't give nice fair lines and those boats I have seen photo's of using this type of method always seem a bit, well, not quite right, sort of the ugly ducklings of boat design.

Derek Kelsall uses a method which sort of is a half way house, the KSS and it seems to be a fast boat building method http://www.kelsall.com/methods.html but still in small boats particularly gives the impression of lots of flat surfaces. I'm not sure with good computer modelling a non flat table could be created to get the right bends in the right places before starting to stitch the panels together, would give a better surface.

But here is the rub though, all that extra design time could probably be better spent ( and more rewarding ) simply getting on with building the boat using traditional foam and female stations.

Pete,
I have done some brief experiments laminating one side of a foam panel and then bending it to the required shape. Once in that shape the other laminate can be applied.
However the required shape was only sufficient to build the Razor design I'm currently prototyping in ply. It is on my to do list to build a fully foam sandwich version to prove the point.
This bloat has curved sides but also it does have Chines. When seen in the flesh they are not that noticeable and will only be seen in the water when flying a hull. I did post some pics on the F16 forum.

One of the objectives of this design was to come up with something that could be built easily from ply or foam sandwich.
Bending a foam panel that has both sides already laminated would be quite different.

Phill,
Are you suggesting a (thin) foam panel laminated on one side then bent (like over a chine form) before the laminate epoxy goes totally off? I would be very interested in this for a Moth hull. For CF cloth too?

Dave,
The idea in my application is to apply the inside laminate.
It does not matter if it goes off completely as the laminate is quite thin. All it does is prevent the inside from compressing which means the outside has to stretch more when curving the panel. A simplified description is this is bent around some frames.
If bent too much it will eventually crack as there is a limit to how much the outside will stretch before failure. This is why I had to do some testing - to ensure it can take the curve without problem. In my testing I used 8mm core cell foam and 200gm plain weave glass. The greatest curvature in the Razor hull is at the transom and it takes the curve quite easily.
You may ask why apply the inside laminate first. The fist laminate can be done on a flat table and I reason that it is just easier to apply a vacuum to the outside once the shape has been formed then to vacuum on the inside laminate.

If I find this to not be the case when prototyping the foam version I can go to an outside laminate option.
Replacing the 200gm plain weave glass with carbon would achieve exactly the same result. Now if you wanted significantly more curvature you would put the laminate on the outside.
Interesting side issue is that I have found that when a light laminate is put on the outside of 4mm gaboon ply I have managed to device a process that will allow me to bend bend it around a 40mm radius without failure and this is without steaming. I'm convinced that there is a great deal more flexibility in the materials that we have available to us than we are currently using. We just have to look for slightly different processes.

Regards,
Phill

Pete, is this to re-deck the Tiki? What does the builder recommend?

Yes. These are home built boats. The designer recommends marine plywood which has limited durabiltiy. In addition a small motor mount is built in.

I'll probably go to some sort of trampoline with an aluminum frame.

so it's non-structural stuff, right?

Pimp it out with tounge&groove teak and be done

There were days when I cursed the brightwork duties on a friend's Choy Lee, but dang those things look sweet when they're all dolled up...