anyone with any experience using c-flex?

Discussion in 'Fiberglass and Composite Boat Building' started by tugboat, Aug 28, 2013.

  1. tugboat

    tugboat Previous Member

    hi again - for those following my build- 30 ft tugboat steam powered (diesel optional)
    30 ft x 10 ft x 2.7 ft draught. displ. 18000 lbs.

    Just to recap- I've looked at every possible material to do this hull in and thanks to one of the posters -I investigated c-flex which for my application makes it possible to do my boat in complex curvature using frp.


    so I've order 450 sq ft of c-flex for my hull(which is 415 sq ft- topsides to keel)

    Just seeing if there is anyone out there who has done a c-flex hull?

    I am doing a boat that is only doable in c-flex due to the easy forming of compound curvature...

    if anyone out there can help me with the initial laminate application it would be of great help

    manufacturers requirements for the initial wetout of the c-flex is:

    " a wax free, non-thixotropic, clear laminating or casting resin(the type used in making fake marble)of LOW shrinkage with a viscosity range between 600-1000 cps"

    IF anyone has done this process without troubles please advise on how you managed it...the c-flex manual also states it IS possible to do the wetout using a very light layer on the outside using normal resins, but it is recommended only for pros. It is also suggested that it is a risk to not use the proper resins.
    vacuum bagging has been ruled out as well...due to the learning curve and costs. Boat hull is scheduled for layup in May.

    I want to thank Groper and Samsam who have helped me greatly in this so far.

    I am now hoping to find someone who has gone through this process.

    things I know so far
    1. can vary the ratio of MEKP to resin to slow shrinkage-but this seems risky
    2. can layup in colder weather in order to slow the shrink rate but again this is not a secure variable.
    3. finding the resin required in Canada is difficult as I am limited to poor choices due to HAZMAT(idiotic restrictions on cross border shipping)
    5. my choices are v-ester, iso and poly.
    6. it looks like there are lots of clear casting resins that could be used with LOW viscosity in the 100-150 cps range so its not suitable. and there is still shrinkage...

    pls note pics of both the right way and the wrong way on this post and see what can go wrong. And see how a well done hull looks like. Its beautiful...

    thanks for everyone's help--I will be posting all the progress.
    If I don't respond to a post it is because I just don't have the time to respond to everyone's posts but I do read them and take EVERYTHING into consideration...

    thanks
    Doug
    aka
    Tugboat
     

    Attached Files:

  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    C-Flex is probably the very last one off, single skin 'glass hull methods I'd choose, just because of the fairing associated, not to mention the weight.
     
  3. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    I think the only time I've ever handled C-flex was at TAFE over 30 years ago, our teachers would collect samples of stuff from suppliers & builders, & cutouts, holesaw biscuits, there was a prop appeture cut out from a long keel yacht, this was from C-flex I think & represented Pars comments with a pretty thick bog layer... long time ago. I'm sure with care a nice job can be done with it.
    Jeff.
     
  4. tugboat

    tugboat Previous Member

    thanks Jeff, they do use a lot of fairing putty using talc and/or microballons but I was thinking I could go with epoxy for that and it should harden up quite nice. the weight isn't an issue on a big displacement hull like this one...

    thanks for the post.
    Doug
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's not the weight I object to with this method (though it is an issue on smaller craft), but the shear volume of fairing required to get a reasonable surface. When you start with a layer of lightly sheathed rods, the resulting surface, regardless of how careful you might be is, well below other techniques, unless working inside a female mold, which would be rare for a C-Flex build. It's like laminating over a pile of rebar and trying to get something fair.
     
  6. pdwiley
    Joined: Jun 2008
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    Location: Hobart

    pdwiley Senior Member

    Just leave the longitudinal lines show and call it a feature....

    PDW
     
  7. tugboat

    tugboat Previous Member

    so be it- it is what it is--ill have to live with the fairing issue- although- there is an argument that the amount of man hours to produce a good plug would far outweigh my finishing hours.. but as mentioned it is going to look rough on purpose. Kind of like the way a instrument can be artificially antiquated...im prepared to do whatever it takes at this point-I've waited long enough for me boat..
     
  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    With one off, single skin techniques, the plug doesn't need to be especially fair, assuming they station molds are accurately cut. It's the substrate the skin will be laminated onto that needs to be reasonably fair, so you start with a "level playing field" and the eventual fairing process is controlled.

    This is the advantage of foam sheets, used as the substrate. They're self fairing, as they go over the mold. Yes, you will need to knock down a few seams to clean it up, but fairing foam is about as easy a task as you can ask for. It's nearly as easy if using tightly spaced furring strips, again assuming the molds are accurate and you don't edge set anything to make them fit. Even if you do, a half a day with a 9" disk sander will knock things down nicely.

    This isn't the case with C-Flex, where no mater how much trouble you go through on the molds, the planks themselves are very unfair.

    As an example, I recently quoted a cold molded build, a triple diagonal planked, 28' very shapely hull, with lots of reverse curves. The station molds are a necessity with any build method, so lets just cover the strips. Instead of using furring strips, I elected to use a white pine, which is cheap and available here. I can get it for $3.30 per 2"x6"x8' length easily. The hull will need nearly 180 full length 3/4" square strips to make a fully stripped mold. No cove and bead, just tight to their neighbors, with the biggest gaps being an 1/8" at the turn of the bilge aft. Ripping these down on the table saw, I can get 12 eight foot long 3/4" square strips per 2x6, so they cost about a quarter a piece. I'll need about $140 in 2x6's and I'll spend a day at the table saw knocking them down to dimension. The result of using a fairly small strip, tightly spaced is a naturally fair surface (after a few hours with a disk sander), that costs little and is easy to install on the molds (staples). I could have used a 1x2 (3/4"x1.5") strip, but the gaps would have been bigger and there would be some fighting with the strips to get them to take a fair "line off" on the molds. The smaller, more compliant strips, though more tedious, makes the resulting surface easier to fair and line off. I could easily increase the strip spacing in the topsides of this hull, saving some strip effort and cost, but considering the real cost of the strips, not a big concern.

    Now, I realize you've decided on C-Flex and this is fine, but I just like the methods that make things easier for me to get a good result. I've worked with C-Flex and know others that have as well and all have the same comments about this method.

    A single skin 'glass hull, using the exact same technique will be just as cheap, fast and fair. You just cover the stripped mold with plastic sheeting and start laying fabrics, until you've bulked up to the required thicknesses. The same is true of foam over station molds, again cover with plastic sheeting and laminated over. C-Flex to me is like making a Chippendale cabinet from rough hewn timbers, then spending countless hours sanding out the rough hewn aspect of the project. To me, I'd rather start with pre-smoothed stock and skip all the bother of "fixing" the material choice after it's done.
     
  9. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    You'll do fine with the c-flex, it's not like you're building a piano, so fairing on something like what you're doing will be easy.
     
  10. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Contact ATC-Chemicals for A. your resin and B. your fairing compound. Canadian, so no issues with transport.
     
  11. tugboat

    tugboat Previous Member

    ...perhaps, but I can say that molding the a plug to the lines in MY particular design would be a nightmare-consider the counterstern, varying radius chine etc., wouldn't have been easy-, -you would either have to cross plank the mold or steam the forming members. With CF all I gotta do is staple it on...besides- the boats done well from the start don't seem unfair to me- and if you see enough pics, the boats look very fair.

    in the end all one does is throw the goop on and sand it down--its not as much sanding as you think...for a rounded stern vessel like mine - it came down to c-flex. as being the only truly formable material. I wanted core- but the costs eliminated that and it was STILL questionable as to getting the curvature to form. I think in comparison its 6 of one half a dozen of the other but the c-flex IS stronger than a standard lay-up in the warp(longitudinal) direction. I know its a B&W pic but that hull looks pretty fair to me. Just my observations...

    may i.c. some pics of the c-flex boats you've built??? curious if you've built a full hull in it..everyone I've talked to on the net says its great...Dave Sintes video really shows just how fair it is when done right...
    https://www.youtube.com/watch?v=-TRhnBZNMu0&list=FLwsdyJEr84xAz2OoXkhPr6Q&index=4
     

    Attached Files:

  12. tugboat

    tugboat Previous Member

    Samsam- this is my thinking-its a tug- so it doesn't need a show room finish.

    but the vids of it and the pics of boats done well, look like the c-flex sets up real fair? its the ones that have shrinkage that seems to give problems.


    btw- thinking of going with all epoxy laminates and using it for the c-flex- its the right cps and shrinkage-(2%) which is less than the low shrink poly and marble casting resins they spec out.
     
  13. tugboat

    tugboat Previous Member

    Thanks Herman ill look them up- I tip my hat to you sir!:)

    I don't know if ATC will sell to a non commercial entity...?
     
  14. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    In your other thread you talk about laminating in 10c or 50f temperatures. I believe with epoxy you'll need a different, faster hardener and with poly you might have problems with cure.
     

  15. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    I do agree heartily with PAR about the C Flex. My personal experience with this material is adding ribs and ribs to limit the flex, and after hours and hours of polyester and fiber sanding (with the associated itching), tons of putty, fairing, sanding, reputtying, and sanding again. For a final result which was at the very limit of acceptable in accuracy, weight and finition. We were well paid and made very good money, but not pride of the result. All the guys who worked on that pensum, hated it.
    I must say that after cold molding wood (tedious), strip plank (fast and strong), and other methods, the C Flex experience was traumatic..."never again". C flex became a very marginal method long time ago.

    C flex plus epoxy laminating is truly spending money in a useless thing. Keep the expensive epoxy for high resistance laminates and sandwiches. Epoxy is rather slow to cure, and you'll become crazy using it for a monolithic laminate.

    Structurally C Flex does not offer any advantage, the price of C flex is not specially good, the weight is rather heavy, and the hours and material needed to make an acceptable finition make it rather expensive for obtaining just a hull what is finally a simple monolithic GRP which main advantage must be low price.
    There are other ways, simpler and cheaper, to get a one off monolithic GRP hull, thus getting all the pros of this material; cheap, fast and having a good strength. The method PAR describes is fool proof and cheap: finition becomes pretty easy.
     
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