Composite (glass/foam/glass) For Beginners?

Discussion in 'Fiberglass and Composite Boat Building' started by CatBuilder, Oct 15, 2010.

  1. War Whoop
    Joined: Jun 2003
    Posts: 661
    Likes: 16, Points: 0, Legacy Rep: 84
    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    So I should have had the test done with huge skins on the wood and X linked foam and the Airex and Corecell a single 1808?? Just to be fair LOL LOL

    Teddy the Point of this is a 488 KG 11 Meter hull and deck 1188 pounds with tanks and interior. Now I did the numbers LONG ago and Airex won for this job.

    [​IMG]
     
  2. AndrewK
    Joined: Mar 2007
    Posts: 490
    Likes: 51, Points: 28, Legacy Rep: 344
    Location: Australia

    AndrewK Senior Member

    Catbuilder, I also think that you should build a boat only if you enjoy the building process and not in order to save money.
    I do understand your dilemma that the second hand production boats are not good sailing boats.
    OK it is possible to build a cat in the 12 - 14m range in that time because it has been done. But these are very basic finishes on the inside and just acceptable standard on the outside. For a home builder three years is an exception rather than the norm, most would take 5 -6 years and some 10+ years.
    A friend has just launched a 12m foam striped catamaran and it cost him AUD $530K and six years of hard labor, 12 moths alone for fairing and painting but the standard is very good and lots of equipment. He could have built the Bob Oram 44 which is a better sailing boat for half the money and half the time.

    If you must build and you are time and money constrained then do not go down the vacuum consolidation path.

    Both timber and foam planking will take about the same time, so the decision is based on cost and personal preference and to some extent resale value.

    Hand laminating timber core, hand laminating foam core and vacuum consolidated foam core will all produce an exceptional boat.
    Which is better depends on your priorities, timber core will be a more serviceable boat as it will not bruise as easily if knocked hard. Hand laminated foam will be lighter than the timber core but not significantly but will be more easily bruised. Vacuum consolidated foam cored will be the lightest and most fragile. The weight difference will be in the order of 200 - 500kg between each case, get actual differences from Kurt.

    Foam, both crosslinked PVC and corecell are fit for your purpose, yes corcell or Airex R63 liner pvc due to their higher elongation are better for hulls or at least below the water line. But not necessary, far more boats are build from crosslinked pvc than the other two and are still fit for purpose. So if you can afford it then do so.

    Both PVC and corecell comes in different grades not just density but service temperature as well so you select the appropriate grade for the service and processing requirements. I have used corecell A in my catamaran hulls, this has one of the lowest softening points (~73'C) so you can still post cure at 60 - 65'C if required.

    Regarding your question on reinforcement orientation, Kurt will specify what is required for the timber and foam versions. But it will be multiaxial, what you referred to is a unidirectional (UD) this comes in both forms warp (along the length, o deg) and weft (across, 90 deg).
    Typically for a timber core you only use a DB +/-45 or a triaxial +45/0/-45 with the 0 deg across the hull. This is because the timber grain is along the hull and has enough strength on its own. The laminate for the foam version could be anything from 0/90, +/-45, a triaxial or a quad.

    If you go down the foam route I differ from Herman and prefer to hand laminate in a concave half hull on its side so can give you reasons for this if need be.

    Andrew
     
    1 person likes this.
  3. CatBuilder

    CatBuilder Previous Member

    Being a bit of a newby here (20 years owning boats, licensed master, but never built), I really appreciate this post. To further the conversation, I'll reply in blue to some interesting points you made.


    Finally, just a quick thanks again for such a helpful post. Just talking about all of this really helps because it solidifies things I already know and I'm learning a lot. Great post!
     
  4. AndrewK
    Joined: Mar 2007
    Posts: 490
    Likes: 51, Points: 28, Legacy Rep: 344
    Location: Australia

    AndrewK Senior Member

    Catbuilder, how do you do the quotes or cut and paste so that I can add further comments in different color as you have done.
     
  5. apex1

    apex1 Guest

    Not Cat builder, but I guess you don´t mind who tells you.

    First click "Quote" instead of replying per "quick reply", because you are automatically in the "advanced" mode then.

    Now go to the chapter you like to insert your comment, separate it a bit from the other text by pushing "enter"
    Then type your text, highlight the text and go to the top of the frame, the big "A" opens a window to choose colours. It is better to choose red for your comments, blue is not very different, and can easily be understood as the OP´s text!!

    Regards
    Richard
     
  6. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Derek uses vinylester, and avoids delamination. A few people have commented on the quality produced by his method. I would suggest that as the panels are flat laid, with vacuum, that the quality control available with the simpler methodology is the key to the success.

    Thanks for the thread BTW, its answering a lot of questions for me
     
  7. TeddyDiver
    Joined: Dec 2007
    Posts: 2,614
    Likes: 136, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Delamination in production boats is maybe more a cause of their production method, in a female mould. The outer layers are laminated first and the core is installed after them. That leaves no reasonable way to see the bond and how well it is set especially when the core is added in larger sheets. It's also been a "cold" mechanical bond in many cases..
     
  8. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    great point teddy - Kelsall makes that point on his website in a roundabout way, and now you have pointed it out, it makes a lot more sense.
     
  9. Herman
    Joined: Oct 2004
    Posts: 1,618
    Likes: 94, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    Lot of things to comment on:

    Delam:
    Indeed lot of boats are made in female moulds (about all of them, but please, no discussion on that). Gelcoat is applied, and the outer skin. many builders not just push in some scrimmed foam (blocks on a mesh) into a wet layer of CSM. No compaction, no filling of the kerfs, whatsoever.
    Slightly more advanced builders first let the outer skin cure, then apply bonding paste, and push the foam into that. Again, issues with bonding can develop, kerfs still not completely) filled, etc.

    The right way to do it was described for instance in technical bulletins from ATC. The foam needs a hot coat, be pressed into bonding paste, and vacuumed down. This is a lot of work, that is why most builders do not do it. (call it ignorance, but perhaps also under-tuition)
    The reason is that bonding paste usually is so dry-ish, that there is only minimal contact with the foam, on a micro-level. This dramatically reduces bonding strength.

    many people complain about the foam being a weak material in a structure, but most pieces taken from commercially built boats, that I have destroyed, did not have any foam sticking to the laminate. I have seen many bad adhered foams, but also huge "neverbonds". (the reason for the desctruction is that I have an osmosis tester, which accepts samples max 10mm thick. The foam has to go in many occasions).

    Another option to get excellent adhesion to foam, fill the kerfs, etc, is infusion.

    I do not feel resin type is of much influence. Good workmanship has so much more influence.

    ----
    Fiber orientation.

    The best way to get a good laminate plan is to inform the designer about the types of glass you can get locally. With this set of materials the designer can propose a laminate plan. If you do it the other way round, you might end up searching for hard-to-find material.

    The principles of multiaxials already have been explained.

    ----
    Your mold

    I understand you have your mould made in such a way that you will need to bend the ends inside to close the front and rear? This will definately not be my prefered method for foam.

    I suggest making a new mold, with exact dimensions, and setting that up. Create a strongback made from 2 steel I beams, level them exactly, and setup frames on that. Cutting the new frames takes some time, but setting them up should cost no more than 2 days.

    ----
    Duflex & construction method

    Please check pricing first. Still, my personal approach would be Core-Cell M over frames for the hull, and X linked PVC for deck and structures.
    All flat parts infused, outer skin hand laminated, inside infused. All later constructin (tabbing, etc) by hand.

    ----
    Postcure.

    There is no temperature at which postcure works best, or is mandatory. It is very simple: the higher you can postcure, the higher the Tg of the resin gets, up to a certain point (ultimate Tg). In general (sorry for metric) if you manage to get to ult. Tg minus 15 degrees C, you will be able to reach ultimate Tg.
    If you do not reach ultimate Tg, there is no real problem. It is better to postcure at 30 degrees C than no postcure at all. (and you are lucky, you are in a relatively hot climate anyhow. Your postcure could be as easy as let the sun do the job).

    Check the datasheet of the epoxy to see what you have. You will certainly find an ultimate Tg, and also some technical properties, usually with the notice: "cure 24h at RT, 10 h at 60C, or similar.
    This does not mean you NEED to postcure following that cycle, but if you do, then these are the tech. specs you can expect.

    ----
    Perhaps later more, honey-do list waiting...
     
  10. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Thanks Herman, great info there. Its ties in totally with a recent article in Professional Boatbuilder Magazine, where they cure a 60 footer for exactly what you describe, with a lot of expensive and labour intensive methods.

    I would imagine that in many smaller boats, its just not economic to even attempt any type of cure..

    David Pascoe, the anti core surveyor in US has a lot of cases to quote, and yet he acknowledges (privately) that Kelsall boats are not on the 'black list'.

    I cant imagine paying say, a quarter of a million dollars to see it peel apart.
     
  11. Herman
    Joined: Oct 2004
    Posts: 1,618
    Likes: 94, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    Some of the samples that I destroyed and where I found "neverbonds" were not a quarter of a million.....

    Whether some sort of cure is economical, depends totally on your own ability and circumstances. For some people it is as simple as installing a heater of some sort, or shorting the thermostat of the workshop heater. For others it can be a challenge.
     
  12. War Whoop
    Joined: Jun 2003
    Posts: 661
    Likes: 16, Points: 0, Legacy Rep: 84
    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    With Airex or Corecell in Corebond, the priming resin is also a part of the adhesive cure process and the perforations not only vent excessive material but give an indication of the bonding,one typically uses under the vacuum bag a bubble pack with the bubbles down which allows for the migration of excess material to the surface. the epoxy materials like SP spabond the excess adhesive must be moved out of the bondline as we look for around 1MM .

    Here is a pretty much textbook job with ATC corebond before cleanup.


    [​IMG]
     
    1 person likes this.
  13. War Whoop
    Joined: Jun 2003
    Posts: 661
    Likes: 16, Points: 0, Legacy Rep: 84
    Location: Sunny Ft Lauderdale Fla

    War Whoop Senior Member

    Do everything right and dark colored boats come out flawless.


    [​IMG]


    and the bagged Corecell Deck


    [​IMG]
     
  14. CatBuilder

    CatBuilder Previous Member

    Here are some more details. I just got my materials list in from the designer. I'm curious if everything everyone is saying will still be valid with these laminate schedules:

    LAM-A 3 layers CDB200 triaxial
    LAM-B 2 layers CDB340 triaxial
    LAM-C 2 layers CDB200 triaxial
    LAM-D CDB340 triaxial
    LAM-E CDB200 triaxial
    CORE-A 6#PVC
    CORE-B 5#PVC
    TAPE 6" triaxial tape for hull frame/hull joint DBM1708
    UNI Warp unidirectional A130 (12" wide strips)

    It would appear making LAM-A and LAM-B might best be done with infusion because they are so thick? Is a hand layup of these schedules a good idea? Will I have overly dry spots as an amateur? Will I be rushed by epoxy curing while trying to get a bag on?

    Would infusion make all of this much easier?
     

  15. CatBuilder

    CatBuilder Previous Member

    Excellent, Herman! Thank you.

    The more I look into this, the more I can see why your suggestions are making sense.

    The Mold:

    Yes, my mold is 1/2 a male hull mold, but it is *not* the correct shape for the hull anyway. It is the mold for the plywood construction method. It simply bends plywood to a "very close" form as you laminate plywood. Then you still must do some bending to get the plywood to the final hull shape. For this reason, my old mold will not work with the new hulls. I need to build a new mold no matter what.

    Hand Layup For Outer Layer of Hull:

    I am nervous that a hand layup will produce a heavy, less strong boat. Am I worrying needlessly?

    Post Cure: Excellent! I think I can get up fairly hot in FL. We've discussed this before, so I won't go too far into it. I can get it to almost 48C in July if I keep the building closed up in FL. Add some electric heaters here and there and I think I can do a reasonable job post curing the entire boat at one time.

    Thanks for your posts. The more I am getting materials from the designer, the more I am understanding your posts. They seem to be going hand in hand.
     
Loading...
Similar Threads
  1. fallguy
    Replies:
    120
    Views:
    8,086
  2. mrdebian
    Replies:
    15
    Views:
    1,379
  3. Chotu
    Replies:
    8
    Views:
    1,208
  4. bajansailor
    Replies:
    13
    Views:
    1,261
  5. cando2
    Replies:
    10
    Views:
    1,394
  6. Robert Biegler
    Replies:
    61
    Views:
    5,507
  7. Markusik
    Replies:
    11
    Views:
    1,338
  8. fallguy
    Replies:
    12
    Views:
    1,609
  9. Mark C. Schreiter
    Replies:
    29
    Views:
    2,800
  10. Scott M..
    Replies:
    61
    Views:
    7,263
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.