c-flex

[spear]

Can someone give me a little bit more info on c-flex .Is there another name for it or is it carbon fibre?Ive never actually seen it or carbon fibre before so Im a little confused.I did some research and found that its got fibreglass rods in it.is carbon fibre a different material altogether.?Im actually looking for a European supplier .Any help on this would be greatly appreciated.thanx in advance.

[Jeff]

C-flex is not carbon fiber - they are different materials all together.

From: http://www.bruceroberts.com.au/build...ods/c-flex.htm

This combination of rigid rods held together loosely, with pliable areas in between , is what makes C-Flex unique in construction materials. In our knowledge, it is the only self-supporting material available today which will conform to compound curves without having to be stretched or deformed in some way. Furthermore, C-Flex will bend sideways, a property which virtually eliminates the problem of having to fit or spile the ‘planks’. Most boats can be built by starting the first ‘plank’ parallel to the sheer line then butting the next ‘plank’ right alongside all the way to the keel.

Aside from the obvious advantage of being able to build an all fibreglass boat without a mold, C-Flex also affords the designer and builder the opportunity to save weight over a conventional fibreglass laminate without sacrificing strength.

This is because C-Flex is an unidirectionally reinforced material and is considerably stronger in the direction of it’s fibre orientation (lengthwise) than an ordinary fibreglass mat or woven roving laminate.This property is used to save weight in the hull shell by running the C- Flex along the lines of anticipated greatest stress (usually fore and aft).

The weight savings also translate into a cost savings. Even though the C-Flex itself costs more per pound than mat or woven roving, the completed hull shell will cost about the same as a hull built with just mat and woven roving. The advantages of being able to build without a mold and the weight savings are a bonus.

Thus the claimed weight savings of using c-flex is because it is unidirectional and unlike mat for example where the fibers run every which way, you can run the cflex in the direction of 'greatest stress' allowing other layers of the laminate, bulkheads, etc. to handle the minor stress direction(s). I've never worked with c-flex, but I wonder how the weight and strength compares to a 'standard' cored layup. It would be interesting to see some side-by-side comparisons, both real world and destructive sample section tests: usually you only see c-flex compared with a standard all-fiberglass mat/roving/cloth layup.

Here is an excellent step-by-step to using c-flex to construct a glen-l hull:
http://glen-l.com/methods/mthdfg01.html

Here is a product info page with pricing:
http://www.glen-l.com/supplies/cflex.html

[gonzo]

The cost savings are offset by the amount of labor involved in fairing. If you are building your own, one off boat, it is great. For production is too labor intensive.

[Dutch Rub]

Siemens fiber glass who used to make c flex used to have a video on hull construction using it- I dont know if they still do or not.

Building on a jig, one off, you will want to make sure your use plenty of jigs, close together. If you don't you will run into a big problems with fairing huge amounts of low spots, in the hull. Also if I recall, since it has been around 15 years since i reesearched it, but the initial resin is different for the initial layup of the strands for building a hull made up entirely out of it. It was also used in coating older wooden hulls for a "few more years" of life. It is bedded in 5200 to hold it to the hulls, initially.

[gonzo]

C-Flex is like a long plank. The fiberglass rods fair nicely. Tie them to the jig with copper wire.

[brian eiland]

Originally Posted by Oyster

Building on a jig, one off, you will want to make sure your use plenty of jigs, close together. If you don't you will run into a big problems with fairing huge amounts of low spots, in the hull. Also if I recall, since it has been around 15 years since i reesearched it, but the initial resin is different for the initial layup of the strands for building a hull made up entirely out of it. It was also used in coating older wooden hulls for a "few more years" of life. It is bedded in 5200 to hold it to the hulls, initially.

I just recently ran across a reference to a wooden vessel that had been
'C-Flexed'. I have a vague memory of this construction material/method, but not enough details.

Are you saying that the original layer is bedded in 5200, a polyurethane, and then subsequent layers in quite different resins, either polyesters or epoxies??

I don't have a problem with the adhesive capabilities of 5200 with wood, or for that matter with other materials, but certainly question any adhesive qualities of polyester resins, that don't even like to stick to themselves, let alone other materials!!

'Fiberglassing' (polyester resin) a wood vessel is the absolute worst thing one can do. The wood portion of the vessel will rot out underneath, and many times without sufficient warning.

Other references suggested for C-Fex???

Cflex is an interesting building method as it allows a builder to build an essentially single skin fiberglass hull without a female mold. I have not heard of applying Cflex over an existing wood hull but then I havent heard all..!

From what I understand of the building method fiberglass rids are laid over a male mold (with short frame spacing..) and then coated/filled with a thick polyester casting resin. When that has all set, fibreglass fabric set in polyester resing is applied over the structure. Finally the surface is faired, painted etc.

There are other methods to obtain a single skin hull, but all require some sort of female mold. Cflex is a viable alternative to building using female mold techniques.

Hal Whitacre
Naval Architect
Whitacre Yacht Design
Annapolis, MD
USA

[david james]

I am considering purchasing the 1974 Spencer 1330 (44') plug designed by John Brandlymayer and built in Richmond, BC by Spencer yachts. Cflex was used as the core material for the plug construction.

During the survey it was noted that "a number of fluid-filled blisters to be present on the underwater body. Some of these were between what appeared to be an epoxy barrier on the outside of the hull, some where between what appeared to be two layers of fairing compound and some were between the inner layer of fairing compound and the skin out coat so that the fibreglass within were exposed and fluid-soaked."

The surveyor did not think much "plugs" in general and suggested specifically that the bottom would be required to be "peeled and reglassed." I don't believe the blisters are structural in nature as 6 areas about 6" x 8" were identified. I believe they could be repaired locally.

I am interested in hearing from anyone who has knowlege of repairing blistered hulls with Cflex and what the characteristics of Cflex is when it gets water saturated.

In addition, I am concerned regarding the actual plug construction lay-up schedule and resulting displacement. I understand that accelerated rig fatigue and the stability curve can be negatively impacted if the vessel is not to the original design specifications.

I am considering retaining a marine engineer knowledgeable about the Spencer 1330 design to review and answer some of my concerns regarding the plug construction.

I would appreciate any comments or suggestions from anyone with Cflex blister repair experience or regarding "plugs" in general.

Thank You