c-flex

[guzzis3]

Hi,

I was wondering if c-flex is still about, what it costs (particularly in australia) and what advantages/disadvantages it offers compared to foam ?

With strip planking becoming so expensive (at least around here, and yes I've priced powlonia) I was wondering if it presented a viable alternative ?

I've searched here and google but haven't found much...if I've missed something then a link or a clue would be appreciated.

 

[PAR]

C-Flex is still available, but not the best one off material for a 'glass boat. It's heavy, requires a lot of fairing and smoothing to produce a sweet hull, so the "goo factor" is quite high, though most of the one off 'glass methods are as well. I'm not sure about pricing in your area, but I remember it being on the high side compaired to single skin and some foams. What design are you contemplating, as some are better suited for this method than others.

 

[Ilan Voyager]

I agree with Par. My personal experience, many years ago, is a lot of dirty itchy job of sanding and fairing hard fiberglass. The result of so many efforts was barely acceptable, too heavy, not very strong and rather expensive in materials and work. Not worth.
Do not forget C-Flex needs a rather costly mold you have to dismantle and throw away later. Compare its final cost (material and work) with the mold for a sandwich composite. If you accept a small weight penalty you can use a rather rigid foam, enabling the use of a very simple mold and easy method of foam strips. And you'll work on a fair surface...

 

[guzzis3]

Thank you for the replies.

It was mostly curiosity as I hadn't been able to find anything recent on it.

I thought the mould was similar to a strip plank mould ?

Strip is stupidly expensive in australia now, as is plywood. divinycell/glass/poly or vinylester are barely dearer than unglassed ply and much cheaper than strip. I was just wondering of c-flex was a viable alternative now.

Sometimes boat building methods go out of fashion/practicality but changes in techniques or other factors make it worth considering again. Others just die, like hot and probably cold moulding.

I downloaded the c-flex manual from the glen-l site. They talk about techniques for avoiding low spots and using casting resin instead of normal laminating resin.

I've been thinking about the issues of re-engineering plywood boats, and eliminating timber in boats generally. No boat in particular. One issue was substituting for 4 mm ply in dinghies. I think I understand the issues with this, getting enough stiffness and impact resistance in a light glass skin is tricky. From my reading I think that 320 gsm biaxial either side of divinycell would be a minimum, but I'm wondering about minimum thickness of the core. I've read of people using 3/8 of 80 kg/m^3, I'm wondering if the thinner sheets would work.

You can strip some of the resin weight out by vacuum infusing flat panels then tape them together, obviously. You going to have about 1.3 kg m^2 + just with the glass, then the core, 0.72 kg. So your well over gaboon plywood weight.

Anyway that lead me to some articles on c-flex and I noticed the stuff seems to have all but disappeared.

Incidentally in case anyone is interested I was reading (and I don't recall where sorry) about building strip canoes with balsa instead of cedar or kirri to save some weight. I have not priced balsa. Might be of interest where weight is paramount but balsa isn't a durable timber in a boat so anything bigger than a canoe/kayak or maybe a rowing shell...

 

[rberrey]

I worked with it some in the 80,s when my uncle built a 22' sailboat , and some friends built 3 shrimp boats ranging in size up to 58' . The shrimp boats that were finished are still on the water , my naighbor just got rid of the one that wasn't finished . Par has discribed C-flex very well , but it is a good product if you want a heavy built boat . I don't think it would be suited at all for a multihull .

 

[SamSam]

Here you go...

http://www.sintesfiberglass.com/id71.html

http://www.sintesfiberglass.com/sitebuildercontent/sitebuilderfiles/cflex20manual-web.pdf

 

[guzzis3]

Yes I found that site and glen l has some stuff. I can't see an actual price anywhere.

Anyway if the result is heavy then as said not suitable for a multihull.

I was just curious.

 

[Steve W]

Having actually built a boat with C- flex back in the early eighties, a Fred Bingham Allegra 24, big sister to Bruce Binghams 20' Flika so an excellent candidate and in fact was the specified method. I found it to be a viable method for this type of hull as it does not require a complicated mould, certainly less of a mould than other solid glass methods, it is easy to lay and self fairing. Yes it does require all the usual back breaking fairing work but so do all one off methods so in my opinion it is a good way to build a heavy solid glass hull and also for repairing large hull damage in solid glass hulls but as others have said, not at all suited for a multihull build.

Steve.

 

[Ilan Voyager]

Having actually built a boat with C- flex back in the early eighties, a Fred Bingham Allegra 24, big sister to Bruce Binghams 20' Flika so an excellent candidate and in fact was the specified method. I found it to be a viable method for this type of hull as it does not require a complicated mould, certainly less of a mould than other solid glass methods, it is easy to lay and self fairing. Yes it does require all the usual back breaking fairing work but so do all one off methods so in my opinion it is a good way to build a heavy solid glass hull and also for repairing large hull damage in solid glass hulls but as others have said, not at all suited for a multihull build.

Steve.

I was a pro boatbuilder. I can tell there are boatbuilding methods faster, lighter, stronger and happily for our tired bodies not requiring a back breaking fairing work...

 

[Steve W]

I was also a pro boatbuilder for over 40 yrs and have only used c flex for the one build as well as a few repair jobs but I still consider it viable for very heavy SOLID GLASS hulls like the Allegra. It is the only method I am aware of for a one off solid glass build that has self fairing properties therefore requiring a minimal mould, exactly the same as for a WRC composite hull btw. It does not require any more fairing than any other one off solid glass method except for methods requiring a much more elaborate mould. Have you built with C flex? its really a pretty good method for one off solid glass hulls. The Allegra is the only one off solid glass hull I have ever built preferring cored hulls but you build what the customer wants and in this case we only built the hull and the customer finished it off himself and did a beautiful job of it at that.

Steve.