need help with a assymetrical cat- plywood and other things

Discussion in 'Multihulls' started by assycat, Apr 3, 2011.

  1. assycat

    assycat Previous Member

    Hey Rick- isnt diab the ones who make corecell?? i think I talked to thier reps a couple years ago(?) ill check the site again..btw i have in my email some thermo forming brochures to use core cell..ive tried forming it that way and the stuff is miraculous...
    anyway-
    looked at aircraft spruce too- they sell honeycomb nomex.
    but they also sell an interesting product called "last-a-foam" 4.5

    for the amount required i could use three layers of 1/4 inch to make 3/4 inch foam. this would cost me 2400.00 also... i have never seen this stuff but its 4.5 pound density per cubic foot which is close to corecells A 500. Noahs does have offcuts. I priced some 1/2 inch- 40" x 40" sheets, and this stuff is the A800 type which is very dense! even without the laminate i probably couldnt put a baseball bat through this stuff... and the price for the amount I need is 2350.00.

    I have looked around at the places you mentioned but the lowest price for the ply i could find in okoume is about 89.00 a sheet..so
    89.00 x 40 sheets= 3560.00! and that doesnt include the resin and cloth..and it has to be epoxy...not poly since it wont stick to wood very well..and is prone to delaminate.
    I think you were right on the money when you said go with core materials they are faster, easier to build and less headaches in the end..so i think -ill make some calls tomorrow and get the skinny on core products...


    *can you please explain -once the hull is layered and glassed you will have a shell...how do you stiffen the hull? do you use wood stiffeners?..and wood bulkheads -or do you keep using compiste materials for the rest of the hulls too?? this is a bit confusing to me, since the plans will have to be altered to work with a core material.
    looked too at the tristars--look like very solid bluewater cruisers! the amas and main vaka are huge!..a lot more material than mine but also more solid for bluewater cruising..i would guess youd need 5/8ths or 3/4 foam...??
     
  2. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    To stiffen my hull,s there will be bulkheads and composite stringers running bow to stern as per designed for a tristar foam build . You would do well to go back to the Horstman site and order Ed,s book ( Foam Fiberglass Sandwich Construction ) or a comprable book from someone else. You should read this book before you buy your materials, it will also give you much of the information needed to transission from wood to foam. rick
     
  3. assycat

    assycat Previous Member

    Thanks Rick--good idea since i was trying to do just that. I ahd called noahs but they didnt give me much in the way to read other than the gougeon bro's. which is more geared to ply...
    Ill pick my self up a copy ...
    cant wait to read it!
     
  4. assycat

    assycat Previous Member

    I just priced 800 sq ft of pascore-which is the same as nida core- poly propylene, honeycomb core- 1/2 inch 5 lb/psf, $1000.00!!!. i also glass two sides of some 4 mm ply and wieghed it at under one lb with two layers of 7 oz cloth...that means the boats hulls would be under 720 lbs for the two hulls..., and with the nida-core- about 400.00 lbs or less..it also seems to be the most durable of all cores ive seen...and least expensive...
     
  5. rayaldridge
    Joined: Jun 2006
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    rayaldridge Senior Member

    assycat-- I just noticed your location. Where in !000 Islands are you? My family has had a camp on Point Vivian for about 100 years.

    Weren't Stilettos built of nidacore? I can't find any reference to pascore on the web-- where'd you see this?
     
  6. assycat

    assycat Previous Member

    HI Rayaldridge- not sure where that is...and to make myself even look more foolish--i dont know what a stilletto is?..is that a catamaran, tri or monohull??..im off to google it right now...
    actually im more situated near the trent severn waterway. but will be cruising that area...
    thanks for the response... i juts got my invoice for the plascore prouct pp honeycomb whioch stands for polypropelyne honeycomb..its basically the same thing as nida-core...have you worked with it?
     
  7. rayaldridge
    Joined: Jun 2006
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    rayaldridge Senior Member

    A Stiletto is one of a range of performance trailerable (with some effort) catamarans. They are an old design , but still considered pretty fast, because they are so light.

    Pt.Vivian is just west of Alexandria Bay. We can see the lights of the International Bridge from our shoreline.

    Where did you get the plascore? I haven't worked with it, but I find the technology interesting.
     
  8. assycat

    assycat Previous Member

    Hi Ray--the plascore is easily available from them direct -big savings since there arent any middle men--i pay 38.90 a sheet (4x 8)for 1/2 inch and 43.00 for 5/8ths! they will send you a sample...i did tests on mine for strength...compared it to wood and other types of core...
    go to www.plascore.com and you can phone and ask for Luke--he can help with technical questions...
     
  9. AsterixDeGaul
    Joined: Mar 2011
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    AsterixDeGaul Junior Member

    You got me all exited about this plascore !

    **From their site
    "
    Plascore Honeycomb is:
    • Light
    • Strong
    • Value Engineered/Cost Effective
    • Tough
    • Stable
    • Easy to Use
    • Moisture and Corrosion Resistant
    • Acoustical and Vibration Dampening
    "

    I hope it was ok to cut and paste like this :/

    The keyword description I was looking for is "durable" but it is not there :/
    I know nothing about this material but I do have some experience with corecell. It is nice to work with and seems very durable. Several Boat manufacturers have used it over the years with good results.
    I only need to believe that plascore is as durable for me to jump on the plascore bandwagon. The price sounds great ... Was that $1000 for 700+ square feet ?

    Marc (sent you a PM)
     
  10. assycat

    assycat Previous Member

    All i can say is --when i did the laminations the bloody stuff was durable.
    i cant say how the material will be over a full hull shell- but i compared it to wood and core cell.



    i did tests this way--using the -"hammer method" i took one square foot of each material and weighed it dry.. then laminated them -then struck each with a standard carpenters hammer until yield point.


    1. 1/8 rotary mahogany(door skin) this came in at 1/2 pound per sq ft.
    first I did one sq ft laminated both sides with one layer and a second one laminated with two layers...

    I struck the unlaminated piece of mahog.as hard as i could strike(im martial artist too and have good technique) it shattered completely!

    the second peice of wood had one 7 oz eglass laminate on each side--this probably increased strength and stiffness by a factor of 20 maybe more!!
    because the initial ply (unlaminated) i could bend easily and break without much strength...
    the second piece with only one laminate per side-i could barely budge. i had to use my foot and pry the ply against a tree before it would bend.
    then i took my hammer and struck this piece. it took considerable force to put the hammer through it...(try it at home!) the result was a complete hole punched through but with little more than a slight hole in the wood at the exit hole. remember this is doorskin ply...so the lamintes increased the overall shear yield, impact strength and stiffness factors considerably. it was remarkable.

    the third peice of ply, i laminated twice per side with 7 oz cloth and weighed it. this came in at just under 1 lb per sq ft. (still light)
    again the strength probably doubled. the first hammer strike did nothing. it bounced off the test panel..after mustering all my strength and technique i finally put a hole in it but it was incredibly strong.
    i have the dent of the hammer in this panel and one hole..you can see the marks..if I had less money to build, id go with this 1/8 inch rotary ply two lmainates 6 oz cloth.

    and at 1 lb per sq ft,its still light..plus its dirt cheap at 12 bucks a sheet.
    conclusion... this was a great balance between strength and cost. i might be a little leary of fastening things to it however. but would epoxy and fasten.

    the plascore:I used a 1 sq ft sample sent to me by plascore. this has a bonding scrim attached- it used little resin to bond each layer. which is contrary to what some might tell you--it does NOT use as much resin as the core cell...

    dry wieght 1 sq ft weight under 1/4 pound i believe about .22 lbs. per sq ft.
    aprox. i dont have the exact figures here.

    This means both hulls at 700 sq ft, would be under 250 lbs!! and around 500 lbs laminated!!!

    next i added 1 layer of e-glass 7 oz cloth to both sides. a double layer. per sider- this laminate would be under 3/4 pounds per sq ft!!

    when i recieved the 1/2 inch PP honeycomb sample, - it was extemely pliable easily bent in my hands...but with the one layer per side- I could not bend it!! miracle stuff. it was even more stiff than the comparable wood and less weight.


    hammer test:
    I struck the single laminate with a heavy blow using the hammer. this again was stronger than the test ply panels of single laminate. the hammer penetrated only the outside layer but not the inside...

    it bounced off the first time and holed it the second. considering this was almost as strong as the two layered ply test panel i did...it was simply amazing.

    with two pieces of ply on both sides its was almost unbreakable and twice or three times as stiff...the single laminate weighed in at just over 1/2 lb(using epoxy). i would probably use one layer of 6 oz cloth and one layer of csm or even 4 oz cloth for lightness and strength.


    conclusion..

    depending on what you mean by durable- i would say the advantage over core-cell is that it wont be pounded to dust(between layers) in a heavy seaway and if water gets into it--it remains localized due to the honeycomb effect-it cannot absorb water or ingress into the honeycomb walls...hence it is impossible for the stuff to become impregnated with water--add to that easy to repair if it does hole.
    i would go with 5/8ths for stiffness. i would use all bulkheads with it as well...and build it monocoque. I find that even closed cell foam can irrigate the foam and soak up water. this sint to say there arent great boats with core-cell--its my second fav choice.

    core-cell:
    I did a test panel of this using 1/4 inch dc A 450 corecell. two laminates per side- it easily buckled. i had some 3/8ths as well and it was mega strong...but heavier than the 1/2 inch honeycomb. i could bend the core by hand with the 1/4 inch(after laminations) but this is good since it resists an impact by flexing with the impact rather than being rigid. core-cell is a great product- but twice the cost. if not three times. i used some PET foam as well and easily punched a hole in it..
    i believe core-cell would have also been more easily holed compared to ply or PP honeycomb.


    conclusions.


    had i used marine play at the recommended 1/4 inch thickness and a single laminate-there is no doubt that at double the thickness of the test ply i used it would out perform any impact test than the others I tried of thicker dimensions--but keep in mind the weight would be substantially greater. meaning a slower boat -and i for one like speed--ease of repair and low cost makes core-cell and honeycomb more viable for a multihull. just keep some epoxy and cloth on board in case...

    if i were to rank durability:

    1. ply-but with sacrifice to weight. and dont get it wet. even marine ply has voids and it costs nearly triple the costs of core-cell or honeycomb.

    2. plascore-overall best choice because of impact resistance, cost and strength to weight ratio.(durability?)
    3. core-cell, sinc eits easy to use -strong but costly.and i dont know if id feel safe with the thickness i could afford.

    durabality- are you defining it as maintaining strength over a period of time?
    durbaility I cannot know..my guess is--they are as good as any other method. built properly--they should last a long time. I will be using polyester for laminates and a light overcoat of epoxy. all fillets and bulkheads will be epoxy filleted.



    I hope it was ok to cut and paste like this :/

    The keyword description I was looking for is "durable" but it is not there :/
    I know nothing about this material but I do have some experience with corecell. It is nice to work with and seems very durable. Several Boat manufacturers have used it over the years with good results.
    I only need to believe that plascore is as durable for me to jump on the plascore bandwagon. The price sounds great ... Was that $1000 for 700+ square feet ?********** yes mark --go with 5/8ths..its only a bit more...at 43.00 a sheet! and much stiffer.

    btw--the only thing with corecell and honeycomb i dont like- is its rip factor. it would seem it might be more easily ripped open compared to ply. but again easy to repair ...this is because on honeycomb the global orientation of the cells are not as resistent to lateral pressure as ply would be.

    as for cedar strip...great stuff..but hard to work and not the same weight to strength ratio as the other core materials
    keep me posted
     
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  11. AsterixDeGaul
    Joined: Mar 2011
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    AsterixDeGaul Junior Member

    I'm thinking that Plascore is better suited for building with a mold, I had a look at the P95 and am not quite sure how you would use it except maybe for constructing bulkheads.

    I appreciated your response very much but for now, I believe my only options are to use either bead and cove cedar or make my own bead and cove out of corecell. :/ ... I can assure you that cedar adds much strength and rigidity to a hull. You did point out something else very interesting though. Until now, I had not concidered using polyester but if I go with corecell, I would do just that and save a bundle on resin.

    I'm not sure but I don't think you can fair Honeycomb core material very well.

    Is there another foam core option ? COST is a major player for me :/

    Marc
     
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  12. assycat

    assycat Previous Member

    Hi Marc--the hulls could easily be built from the honeycomb. no need for fairing really. same as doing flat panels with foam core...how do you fair with core-cell? honeycomb can be thermoformed same as corecell. so it would be easy to form your round bilge hulls. ive seen cedar used in amas of trimarans. and it should be fine for your hulls...
    if you know this method and it works for you--use that one...

    foam core is expensive (but less than marine ply....corecell is one of the better deals out there..they sell precut bead and cove planks..call noahs and ask them about it...

    cheers.
     
  13. AsterixDeGaul
    Joined: Mar 2011
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    AsterixDeGaul Junior Member

    I think it may be time to give Rick a call. (I'm assuming Rick still owns and operates Noah)... I haven't talked to him in years :/
    Last time i checked into corecell, it was being made by ATC here in Canada. I understand corecell was sold some years ago. The last time I inquired on the cost of bead and cove foam, it was WAY too expensive :(:(.

    I'm still curious how you would used plascore. Would you glass one side first and then build same as if it was plywood ? Do you even need to glass one side first ? You saw what I intend to build, I don't think it would work for me :/
     
  14. AsterixDeGaul
    Joined: Mar 2011
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    AsterixDeGaul Junior Member

    Same way you would fair glass or wood ... Sand it :p:p hehe

    Tomcats Boats has been working on an F32(?) all carbon with corecell.
     

  15. assycat

    assycat Previous Member

    Marc-its the same process as core cell--you would make a mold- the in your case- you would either use double cut and lay strips or heat bend the sheets to form over your mold- its very easy to work with--in fact with the 1/2 inch(for your boat it could work with two laminates)it could cold form to the hulls curvature--then you do one side of laminations- remove the mold then do the other side..same as core cell- exactly the same process..no big deal..
    the red cedar is a good idea too--its light..but i priced it out to be more than plascore...
     
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