Traditional Build with Corecell

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Apr 7, 2017.

  1. fallguy
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    fallguy Senior Member

    Also, if the keel section of the hull has a bit of twist to it, wouldn't it be a problem to glass it double on the bottom and 900 quad inside and get it to take the bend? Richard had earlier suggested it might be necessary to go only glass at the front of the vee. (I do have a 1:10 crude model I can provide a picture of if it helps).

    For the flat panel notion, I'm a little nervous 600 biax on the outside and 400 biax and 400 0/90 on the inside is going to get too rigid as well.

    How much bend are the panels going to allow for each configuration.
    A. 600 biax outside.
    B. 600 biax outside 400 biax inside
    C. 600 biax outside 400 biax inside 400 0/90 inside
    D. 600 biax outside 600 biax outside (as in the bottom).
    E. 600 biax outside 600 biax outside 400 biax inside
    F. 600 biax outside 600 biax outside 400 biax inside 400 0/90 inside.

    Or more simply at what point in the above configurations are the panels too stiff to take the mold shapes for the hull panel I've shown on 90mm stations. I'd rather not 'experiment' and build a full panel I can't bend into the mold later.

    Another possibility I like is build the flat panel bottom and apply tapes and the second 600g biax when the boat is flipped (by hand) and that way I'd get the bottom glass to go all the way across the keel and incorporate the first hard chine as well on each side. (or before like you did, but after would be easier for this build) and that would eliminate D, E, and F above from the flat panel work. And then I'm only worried about whether B and C are too stiff to take bends.

    Is 400 0/90 the same as 400 uni?

    Again, thanks.
     
  2. groper
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    groper Senior Member

    Vac bagging is more difficult than infusion. It's also messy, you still breathe up the fumes and you have a limit on the size of panel you can laminate within the pot life of the resin, which is very small if you attempt to laminate both sides of a panel before getting the bag on.

    I don't know why you are so scared of infusion- please explain why?

    If your going to learn something you've never done before such as build a boat, what not learn infusion aswell?

    As to the bottom panels of your design- the warped panels which go from about midship forward to the bow would not be able to bent like that. For these you simply glass one side of the foam or simply use raw foam and offer them into position before laminating them on the other side at the same time as taping them into position and joining them to surounding topsides. Small areas like this a little wet laminating is no big deal and its in an area which won't require a perfect finish either.

    Over building is overbuilding, it's not nessesary and shouldn't be done. Stick to the plans and the boat will be very strong already. Designers of boats use a safety factor or 3-5 which means the design is already 3-5 times the strength it needs to be- Adding more is a waste of time and money and adds unessesary weight...

    If you build a table, DONT do what I did (and so many others) and use melamine sheets! The gaps between sheets are impossible to vacuum seal and your left with lines in your finished panels aswell. Spent the time initially and make a perfect surface thats free from defects and is tough enough to reuse for the entire build, and will not leak vacuum.

    10m cat is ok for a couple. Obviously that depends on your personal preferences and needs. For a long term home, I think it's too small and would suggest a 40ft cat as a minimum. If I do build another boat it will be a sailing cat of at least 45ft. I'd rather not build again tho, it's far better financially and in terms of time spent to achieve the result , to find a used boat and fix it up....I'm looking at 3 catamarans right now which are all less than 10 years old and are for sale for less than just the materials and equipment which they have bolted on. I can't justify spending another several thousand hours of my life when i see these...
     
  3. fallguy
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    fallguy Senior Member

    All the experts I've talked with have warned against infusion for an amateur one off build.

    I'd rather not name them, but three well known people in the boat building world.

    I was planning on going with silvertip slow if I use vacuum on individual panels or for laminating on the boat. It has a 60 minute time to gel. If you have everything ready, I see no reason why you couldn't vac bag that, and for a few of the times, I could even do both sides, or I could vac bag just the top side with fast hardener and flip it after an hour.

    What surface would you build if not melamine? I could probably buy a 4' roll of formica 32' long, but that would need to be epoxied down to ?melamine?

    Thanks.
     
  4. groper
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    groper Senior Member

    Their advice holds true if you were to attempt a full hull infusion or something to that effect. But this is not what im suggesting. Infusing some flat panels is much more straight forward and you start with small ones to get the hang of it. It doesnt take long to master and then youll want to go for the largest panels you possibly can because you will have learned how much more efficient it is. Forget vac bagging! Ive been there and done that, theres no way you can vac bag an entire hull panel working alone. Attempting that is a recipe for disaster.

    For a table surface id probably just bite the bullet and use plain 3/4 or 1" MDF atop steel frames. Id resin squueggee coat it, bog it, 2 person giant longboard sand it, bog it again, longboard sand it, prime it, and finally coat it with a good hard 2 pack coating in a dark colour - similar to making a mold.... then apply a good semi permanent mold release. Rememember every panel you make on this will be only as good as the surface you created here- so make it good!
     
  5. AndrewK
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    AndrewK Senior Member

    fallguy; now that you are considering the flat panel option I have attached an old spreadsheet I was using for my infusion jobs.
    Enter your material cost to get a good idea of relative cost of hand lamination versus infusion and vac bagging.

    Vac bagging is more labour intensive but less technically difficult than infusion, so may be in disagreement with groper on this one. You can still do very large flat panels on a table on your own. I personally would not bother unless you do both sides at once.
    You also require different types of pumps, for bagging 20-60% vac is the norm, infusion you want 100%.
    Most common infusion pumps are oil vane pumps and these are designed to run at full capacity so not a good choice for vac bagging.

    Different cores for the three different processing methods.
    Plain sheets for wet lamination, perforated at ~50mm centres for vac bagging double sided panels, perforated at ~20mm centres and grooved or perforated only plus transfer media for infusion.
     

    Attached Files:

  6. AndrewK
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    AndrewK Senior Member

    When strip planking compound curve hulls in foam in order to produce a fairer finish as well as having at least a partial skin on one side to aid in retaining the hull shape when removing from a mould one approach is:
    To produce large long panels with only the 0 deg fibre along the length of the panels on both sides. These are then ripped up to appropriate widths to suit the hull curvature.
    After the planking is complete the rest of the laminate schedule is completed, eg 90/+45/-45 deg fibre.

    You could use this approach when doing your hull shoes, this would address both of your concerns regarding the ability to induce a twist and bend in the bottom chines as well as retaining a true shape.
     
  7. Beamreach
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    Beamreach Junior Member

    Groper mentions he used 40 pounds fibreglass to 20 pounds resin ,is this the normal ratio we can use to calculate how much resin is needed to infuse a large panel.
    How much Vacuum Pressure is needed to be able to do both sides of a panel at the same time using foam perforated for Vac?
    Recommended best pump for two sides at once infusion?
     
  8. jorgepease
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    jorgepease Senior Member

    The Welch pumps can be had cheap -$600 for a $3000 pump on Ebay and they are tough. You want to pull 30", the cfm is not important. Get one that doesn't mind being run continuously.

    I calculated my resin at 50-50 even though I believe it's normal to be at 60-40. Plus I added a bit more for core, and consumable absorption. I never had that much left over.
     
  9. Beamreach
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    Beamreach Junior Member

    Thankyou Jorgepease.
    I have a used pump ,will check out it's specs ....
    50-50 helps....learning here as we go.....
     
  10. groper
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    groper Senior Member

    The fiber and resin ratio is approx 2:1 if you infuse epoxy laminates ie 66:33 fiber to resin ratio. You mix closer to 50-50 to account for waste resin in the flow media and resin lines, peel ply etc etc it all adds up but it depends on the system your using and the types of materials etc.

    The orrect approach is to measure everything and create a spreadsheet that calculates the exact amount ypu need for a specific job.
     
  11. AndrewK
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    AndrewK Senior Member

    To be more specific the 2:1 ratio is a good guide if you are at sea level and have a very good pump that can do 100% vac and are using stitched only UD fabric. No combination UD with chopped strand backing.
    The spreadsheet calculates all this, as can be seen a lot of resin is required to fill in the core surface itself.
    Put in some numbers for surface areas (m) and cloth weights in (kg) and see how the different processes compare.

    31-33%wt resin content was what I was achieving with 400 to 800gsm stitched fabrics available locally. But there was one 1000gsm UD tape that I could get 25%wt resin content.
     
  12. fallguy
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    fallguy Senior Member

    how about a welch 1402 duo seal?
     
  13. jorgepease
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    jorgepease Senior Member

    I have it, it's great!
     
  14. groper
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    groper Senior Member

    That would be overkill!

    I used a little 1.5cfm vac pump designed for HVAC technician service work. The CFM is not important with infusion, only the ultimate pressure. You can simply use one of the $200 ones... Just look for hvac 2 stage rotary vane vacuum pump.

    If you read through my build thread I'm pretty sure I also showed ways of dramatically reducing the infusion consumables costs. You don't need much of the expensive gear the composites suppliers tell you that you need. You can find everything you need at Home Depot... If I was going to do it again, I would not opt for the flow media style infusion method but rather the infusion grid scored foam method. There is much less waste to deal with and it's easier and quicker to setup each infusion, it really is quite painless...
     

  15. jorgepease
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    jorgepease Senior Member

    I second that! infusion flow media sucks.

    The thing about the Welch is they are readily available over here on Ebay. They can take a lot of abuse and are really quiet ... imagine I sucked a bunch of epoxy into mine and it froze when the epoxy hardened. Took it to the pump shop and they said it's not a problem lol.
     
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