Carolina flare build and materials

Discussion in 'Boatbuilding' started by lenm, Dec 11, 2014.

  1. WindRaf
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    WindRaf Senior Member

    no, superlaminato is not a trade name, is a marine plywood made with more layers than normal and with the best wood. The superlaminato has the highest ratings from all certification bodies.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    The flare won't be obtainable from ply sheets anyway, no matter how fancy the quality !
     
  3. DennisRB
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    DennisRB Senior Member

    Thanks PAR. If you look at my link and scroll down, there is a west sytem article that shows the weights VS glass etc. I hope the original poster on that forum won't mind me linking their pics here.

    Some good info but it does show something like 3 times the total weight for similar weight cloth layup, and 6 times the amount of epoxy compared to biax. Not that the weight would matter on this build as you say. It makes much more sense than kevlar on the outside.

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  4. PAR
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    PAR Yacht Designer/Builder

    These sort of line up with my less than scientific tests Denise, though the numbers above are difficult to interpret, without some tedious, but simple math, to bring the fabric weights in line, so you're comparing apples to apples. For example the Xynole and Dynel are fairly close in fabric weight and epoxy need, yet the 6 ounce cloth is nearly twice as heavy in fabric weight. Again, some simple math would level these values for a better comparison.

    Windraf, please do your homework. That's a re-badged Nautico product and marketed under the brand name "Superlamellare" in your part of the world. It conforms to the usual standards and is an all mahogany laminate, which isn't unusual (several manufactures build all mahogany panels). It's not any better than other panels that make the same conformance, though it sure cost more as a re-badged product, marketed as being something special.
     
  5. DennisRB
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    DennisRB Senior Member

    I done some rough maths to come up with the figures I posted. For the same weight cloth, the final Xynole laminate will be 3.3 times heavier, and use 5 times as much epoxy than biax glass (no wonder it is better at abrasion resistance if you use the cloth weight as the yardstick). So the question I am interested in is, if I use 3.3 times as much glass to equal the same weight as the final Xynole laminate (BTW this still uses almost half the epoxy). Will the Xynole still have better abrasion and impact resistance? Which will be cheaper? Clearly the glass will be much stronger and stiffer.

    So my apples to apples comparison is not based on the weight of the cloth, but on the weight of the final laminate. Which is fair enough as it will probably be cheaper and much stronger, so I wonder how it would stack up for impact and abrasion resistance when compared this way? Pitty the west system test did not also test a thicker glass laminate.
     
  6. WindRaf
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    WindRaf Senior Member

    no, superlaminato is not a trade name, is a marine plywood made with more layers than normal and with the best wood. The superlaminato has the highest ratings from all certification bodies.
    super means more
    normal plywood has not one layer every millimetre
    normal plywood is not in mahogany
    all strengths of superlaminate are higher than those of normal plywood
    the superlaminate is always certificate

    to do the housework go YOU, little web's snooty, ignorant as a goat
     
  7. DennisRB
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    DennisRB Senior Member

    WindRaf. If "superlaminato" is such a big deal. Why does nothing come up on google? Why is this thread the only thing on the whole internet which talks about it? Is everyone else in the world as ignorant as a goat too?
     
  8. WindRaf
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    WindRaf Senior Member



    superlaminate here is a material widely used from a long time
    perhaps because we have the most stringent certifications in the world
    is normal that it is on google, like carbon, kevlar or aluminum marine

    I was only talked about the question of the thread, then PAR has planted an infinite controversy.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    ......the housework...lol.
     
  10. gonzo
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    gonzo Senior Member

    Mr Efficiency: We have been building Carolina boats with that kind of flare in plywood for decades. This is a typical shape.
     

    Attached Files:

  11. WindRaf
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    WindRaf Senior Member

  12. Milehog
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    Milehog Clever Quip

    Who is providing the plans-templates?
    I ask because there is a player with an attractive website selling unproven junk.
     
  13. tom28571
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    tom28571 Senior Member

    Sheathing material tests

    Many posting on this thread seem to be talking past each other, resulting is more flame than understanding. I had some problems relating the tests in WoodenBoat to my experiences so decided to make some objective tests of my own. The below study was published 15 years ago but not much has changes since then to alter my conclusions.

    Unfortunatel, teh tabulated results did not copy to the thread but I will attempt to add them. Some or PAR's data appears to have come from my tests so that is apartial answer.


    Testing Sheathing Materials
    By Tom Lathrop
    1999

    In most of the books and articles written about building plywood boats, the authors recommend that fiberglass cloth set in epoxy be used to sheath the exterior or, perhaps, just on the bottom to increase abrasion resistance when the boat scrapes against beaches, docks, rocks or other scuzzy stuff. I’ve always wondered at this advice since, in my experience, fiberglass never seemed very resistant to abrasion. Those of us who have used fiberglass know that care must be taken when fairing this kind of sheath to avoid sanding through the material. Especially with a rotary sander, it is all too easy to go right through the fiberglass and ruin the job.

    About 30 years ago, armed with a Defender Industries catalog, I set out to stop the fir plywood bottom of my Windmill racing sailboat from checking and ruining a new paint job within a few hours after launching each spring. I removed the paint, carefully faired the bottom and following Defender’s instructions, laid on a sheath of Dynel cloth set in their epoxy. The first thing I noticed was that it was much harder to sand the Dynel than fiberglass but a smooth and fair hull bottom was finally achieved. At any rate, the finished bottom was a great improvement over the painted plywood and remained in good condition for many years. More will be said about this application later.

    A few years later, I built a cedar rudder for the Windmill and sheathed it in Vectra polypropylene, which seemed about as difficult to sand as Dynel. However, it was easier to achieve a nice surface since the cloth had a much smoother finish which looks a lot like regular 10oz fiberglass cloth.

    One thing of note about both these materials is that they required more epoxy than 10 oz fiberglass and a sheath made with either would be heavier than one made with 10oz fiberglass. This could be a problem in racing boats or other craft like kayaks, where it is very desirable to keep the weight to a minimum. I built a few stitch & glue boats in the following years where fiberglass tape was used on the plywood seams, but had no further need to sheath an entire hull.

    In 1994, I built a 15ft Bay River Skiff designed by Graham Byrnes, which we named the “Loon”. This is an all purpose cat ketch rig that was built for beach cruising which sails well, rows well and takes outboard power up to 10 hp. Loon was a wonderful little boat and the easiest to launch and get sailing that we have ever owned. If any boat is worthy of the name “perfect skiff”, this is the one. Since this boat was never intended for racing and needed bottom protection against beaches, rocks, oyster and or mussel shells, I decided to give it a good sheath to withstand these rigors. Based on my experience with the Vectra polyethylene, I decided to sheath the hull exterior with that. I also topcoated the bottom with System Three’s Copperpoxy, which had been left over from a larger sailboat job. This boat has been sailed, trailed and beach camped over much of the United States and into Canada and Baja, Mexico, while surviving being dragged over many beaches and shells with only minor scratches on the bottom, none requiring any repairs.

    This brings me to a project that occupied me for several years in the design and building stages. That is, the 24ft cruising powerboat “Liz” which was described in two previous articles in Boatbuilder Magazine. While weight was an important issue in the design of this boat, it could easily absorb the extra few pounds of a heavier sheath with no ill effects. I had been recommending the synthetic materials instead of fiberglass to others but had only my anecdotal evidence and no real data to back up my beliefs. Before sheathing the exterior of “Liz”, I determined to make some tests that would either prove the validity of, or put the lie to these claims. I set out to test abrasion resistance and peel strength of the various materials that were on hand. I do not consider a thin sheath to add any significant strength to a boat hull and believe that this is better left to the basic structure, so any added strength or stiffness is just a bonus. What was desired for was a “tough paint job” similar to that used on the Bay River Skiff that could withstand some abuse without damage.

    Abrasion Tests

    To make the tests as objective as possible, I thought to make the procedure automatic so that operator error might be eliminated. The setup shown in the photographs was designed to make the abrasion tests. A 30rpm gearmotor was available so it was used to cycle the test sample. The plywood cam attached to the motor shaft was given a pattern that would allow contact between the sander and the test sample for about 25% of each rotation to help avoid heating the sample. The hinged arm with the test sample mounted underneath has a roller mounted to contact the cam. A Makita 8-inch rotary sander set to run at its lowest speed was mounted so that the test sample contacted the sander disc near its outer edge when the roller is in the flat area of the cam. A 40-grit sanding disc was used and an air hose blew on the sanding area to clean the disc and further keep the sample cool. A small bungee cord keeps the test sample pressure even on the sander. One test was made with a 60-grit disc but I felt it was too slow and increased the risk of clogging the sanding disc and influencing the results.

    The samples were cut from the different materials and epoxied to 3 by 6-inch plywood bases. To accurately measure the time taken to sand through the sample, a fine copper wire was placed on the plywood before the samples were epoxied in place. The ends of this wire were connected to a battery-powered clock so that when the wire was cut, the clock stopped. Doing this job visually proved very inaccurate. To start the test, both motors were turned on and the hinged arm was allowed to contact the cam at the same time that the clock was started.

    Two samples each were made for the following materials:

    1. Epoxy alone – two coats.

    2. 9 or 10oz fiberglass tape. (Uncertain of weight)

    3. Two layers of 9 or 10-oz fiberglass tape.

    4. Dynel.

    5. Vectra.

    6. Xynole.

    This seems a lot of trouble but since unbiased and believable results were wanted, I thought it worth the effort. Besides, it was interesting work and a nice break in the building effort. The results are tabulated in Table 1.


    Table 1
    Abrasion Test Results

    Sample - Sheath Thickness (in) - Abrasion time (sec) - Abrasion time rel. to epoxy - Abrasion time rel. to 9oz FG - Abrasion time per unit of thickness Rel. to 9oz FG


    Plain epoxy 0.018 40 1 0.59 0.53
    9oz fiberglass 0.02 66 1.7 1 1
    2 layers 9oz FG 0.039 133 3.3 2 2
    Dynel 0.043 250 6.25 3.8 1.76
    Vectra 0.032 153 3.8 2.3 1.43
    Xynole 0.053 436 10.9 6.6 2.5

    Weights of these materials may be of interest also.
    Sheathing weights:
    One coat of epoxy = 0.036 lb/sq ft
    Two coats of epoxy = 0.059 lb/sq ft
    Three coats of epoxy = 0.081 lb/sq ft
    6 oz FG cloth w/3 coats epoxy = 0.142 lb/sq ft
    10 oz FG cloth w/3 coats epoxy = 0.195 lb/sq ft
    XYNOLE cloth w/3 coats epoxy = 0.36 lb/sq ft
    KNITEX 1808 biaxial (non woven) FG cloth w/3 coats epoxy = 0.46 lb/sq ft
    These sheathing weights are approximate and will depend on how the individual applies the materials but may be helpful for those interested in these details.


    It seemed clear to me that Xynole is the winner in this group for sheathing most small boat hulls when an abrasion resistant surface is wanted. Rated on the same thickness, it is 2 ½ times more abrasion resistant than fiberglass cloth. Perhaps more importantly, it is over 6 ½ times more resistant when considering a single layer of each. All of the synthetics are easier to handle and apply than fiberglass although they take more epoxy to fill the weave. On the latter point, I don’t consider that a disadvantage since a thicker epoxy coating will definitely reduce the amount of moisture that gets through to the wood beneath. Vectra is almost as easy to finish as fiberglass cloth and gives added abrasion resistance and flexibility to the sheath.

    Based on the above data and personal preferences, my choices for use on various jobs are:

    1. Fiberglass cloth in a suitable weight for small boats where weight is paramount and also on cabin tops and decks.

    2. Xynole on hull bottoms and topsides when maximum abrasion and water resistance are wanted.

    3. Vectra on hull bottoms and topsides for abrasion resistance when Xynole would be too heavy.

    4. Dynel in no applications. (See peel strength tests below)

    Other Materials

    One other material was tested which is quite different from a simple sheath so is not included in the table. That is Knytex, a non-woven bias-ply fiberglass material that is knitted together and with a fiberglass mat added on one side. In addition to providing a single layer abrasion resistance almost as good as Xynole, it also adds a lot of stiffness (and probably strength) to the substrate. It takes even more epoxy to cover it than the xynole and may need another layer of glass cloth or a lot of fairing compound on top to help make it smooth enough most people. Of course it can be sanded smooth, but that would take a lot of effort and take away some of the strength. The finished product will be very good but also add considerable weight to the hull so I did not include it in this group. When weight is not an issue and in combination with one of the other fabrics, it may provide the toughest sheath of all.

    The reason for its stiffness is that the fibers on each side of the material run straight in one plane and do not weave from one side to the other as in ordinary woven cloth. Therefore the tension and compression forces of bending are directly resisted by the glass fibers. On a weight basis, this material is far stiffer than any woven cloth or roving. On the other hand, its life when subjected to repeated bending cycles may be inferior to woven cloth for the same reasons, so I can not recommend it for use on thin plywood panels where the combination would be repeatedly flexed.

    Of course, based on the information that has been published, Kevlar is superior to any of the above in abrasion resistance. However, its high cost and difficulty of use would make it a poor choice for any but the most demanding high-tech applications. Some applications of narrow strips or Kevlar pastes have been offered for use as keel protectors on canoes and kayaks and would work well as wear strips on dinghies that are beached often.




    Peel Resistance

    Testing the peel strength of these materials proved more difficult and uncertain than the abrasion tests. The results are apparently much more dependent on application technique than abrasion which was so well linked to the fabric. Nevertheless, some results were obtained that make a choice in this property possible.

    The test bed consisted of making samples in the following form. The fabrics were applied to plywood substrates as before but special provision had to be made to allow for the application of equivalent peeling force to the material. A piece of plastic tape was placed across the plywood under part of the fabric sample. After epoxying the sample, the end of the fabric over the plastic tape could be lifted so that all the pulling force could be applied in a straight line across the sample perpendicular to the pulling force. As shown in the photo, small wood blocks were tightly clamped with a C clamp over the lifted end of the fabric. This clamp was attached to the base of the test structure. The sample was mounted under a hinged arm and a hydraulic jack applied the peeling force to the arm. The jack rested on a common bathroom scale to measure the force. I did not bother to take into account the relative moment arms of the sample and the applied force.


    Peel Strength Tests Results
    Sample Starting peel force (lbs) Steady peel force (lbs) Sample width (inches) Peel force lbs/inch width
    9oz fiberglass #1 50 30/20 2 3/4 18.1
    9oz fiberglass #2 70 20 (1/2" of tape broke a 70lbs) 2 3/4 25.5
    Dynel #1,2,3,4 Two samples broke completely off at tape/glue line while bending the material up for assembling the clamp. One sample broke with very little force applied. The fourth sample withstood 30lbs before tearing a small amount of plywood surface and then breaking apart.
    Vectra #1 70 60 2 5/8 26.7
    Vectra #2 60 55 2 5/8 22.8
    Xynole #1 Clamp slipped at 200, Tape broke at 250 2 7/8 87
    Xynole #2 260 260 2 7/8 90.4



    Except for the failure of the Dynel, the relative peel strength of the rest of the samples were as expected. When either fiberglass cloth or Vectra are peeled, they almost always break away at the interface of the inside of the cloth and the epoxy. This indicates a weak bond between the epoxy and the material in the cloth. This can be seen in the photograph where the underside of the peeled material is almost clear of epoxy, unlike the Xynole where the cloth and epoxy both peeled away as a single unit. Fiberglass sometimes does this also but Vectra never did. Both materials are made of fairly continuous strands that are closely woven relative to Dynel or Xynole and both have a smooth surface. Dynel appears to adhere to the plywood as well as the Xynole but the tensile strength is too low to test the peel strength. Like Vectra, Dynel and Xynole are synthetic plastics and it is very likely that epoxy does not bond well to their individual fibers either. Why then is the peel strength of the Xynole so high?

    Xynole has something else working for it. It is made of shorter fuzzy fibers loosely woven in a relatively open structure. The epoxy can thus easily penetrate into and through the fabric to create a mechanical bond and form substantial connections with the epoxy on the far side. It would seem evident that the peel strength of these fabrics is directly related to the amount of coupling of the epoxy on both sides of the fabric and less so to the material the fabric is made of. Therefore open weave fabrics have higher peel strength than closely woven fabrics regardless of the inherent tensile strength of the fibers.

    Taken further, this explains why products like Peelply work. Peelply is a thin, tightly woven synthetic fabric with a slick finish. Like the other synthetics, the fibers of Peelply do not bond to epoxy very well. However, the principle reason Peelply works as it does is that the resin that penetrates through to the other side is only in very thin tendrils of epoxy through the tiny openings in the weave of the cloth. These thin tendrils are easily broken and so ripping the material away leaves a fairly smooth surface that often eliminates the need for sanding. I find that almost any of the similarly constructed synthetic fabrics from a mill outlet store work as well as much higher priced Peelply.

    I have no explanation for the poor showing of Dynel. Many have used it for various purposes but I can see no reason to use Dynel on other than a traction surface and I would much prefer fiberglass with a non-skid additive in the topcoat in that application. It is true that the samples I used were fairly old but if the material deteriorates in storage to the degree indicated by the peel tests, I would never use it. There is also the results that I found on the bottom of the Windmill where the material broke along fir plywood check lines to consider. Hopefully the much later introduced Xynole will not exhibit the same failing over the years. Since these fabrics are only available from Defender Industries, I hope that they have conducted or will conduct some tests of their own to establish aging properties of these materials.

    I am certain that this does not close out the discussion on sheathing fabrics. These experiments are not very exhaustive but, perhaps, do give some basis beyond speculation as to the value of the different fabrics tested when used in some of the possible applications that a wooden boatbuilder might encounter. The Xynole/epoxy/Awlgrip finish of “Liz” has taken several bumps on pilings and docks with only superficial damage. None of the fabrics are adequate to sheath a plank-on-frame hull where movement between adjacent timbers can be expected. Those who have had success at this do so by making a thick sheath strong enough to resist such movement.
     
    Last edited: Dec 15, 2014
  14. lenm
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    lenm Junior Member

    Hi Milehog,
    Thanks for raising concern.
    It is a local NC designer/architect. I believe the plans have been refined over a dozen builds+boats in service inc 'performance reviews' so should be all good hopefully.

    Tom, thanks for your detailed reply. Very interesting read. Thanks for sharing.
     

  15. tom28571
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    tom28571 Senior Member

    Sorry my table does not transfer very clearly but maybe it is decipherable.

    I suspected you were referring to the Ocracoke 20 from B&B which you just confirmed. I have some experience with this boat and can say that it is well capable of handling rough conditions. It was laminated of occume plywood over a male mold and sheathed inside and out with non woven biaxial fiberglass. That would be my choice of construction for such a boat with a non-developable hull skin also.

    Would have liked to have it available yesterday when we did some sea trials of the new B&B 44' SWATH power cat. The Outer Banks 20 we used was not quite fast enough to keep up with the cat at its top speed of 23kts. With 90hp the Ocracoke 20 did 36kts with five adults aboard.

    One thing the OP had in his list was that he is not concerned with weight. That I cannot understand as weight is always a serious parameter in planing boats. A boat for his intended use does not want to be flimsy but weight is a prime determinant of performance in this or any planing boat.
     
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