Fiberglass Layup Schedule for 70ft fishing boat

Discussion in 'Fiberglass and Composite Boat Building' started by makobuilders, Apr 17, 2016.

  1. makobuilders
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    makobuilders Member

    Following is a summary of the layup schedule for a 70ft X 14ft X 5ft, 56 ton longliner. The vessel is long and lean with moderate D/L, but the scantlings seem a bit light for a vessel for open ocean work. There wouldn't be an issue with trading some cargo carrying capacity for a thicker hull (to maintain the designed DWL). I would appreciate some feedback.

    Raw Materials:
    1) 1,600 g/m2 alkali free fiber glass woven roven (EWR600)
    2) 300 g/m2 alkali free chopped strand mat (EM300)
    3) Resins are EL-4052 (roving) and EL-4080 (chopped)
    4) Gelcoat is isophthalic neopentyl glycol (white color, brown undercoat)

    Hull Lamination in 3 Layers:
    1st) M300 chopped with 4080 resin
    2nd) 7 layers alternating chopped with roving with 4052 resin
    3rd) 7 layers alternating chopped with roving with 4052 resin

    Built Up Thicknesses:
    -Bottom 10mm
    -Sides 8mm
    -Square keel (internal ballast) 20mm
    -Flat keel 15mm
    -Transom 15mm
    -Tanks 8mm
     
  2. Canracer
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    Canracer Senior Member

    Layer 2 and 3 are identical?
     
  3. SamSam
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    SamSam Senior Member

    What sort of resins are the EL-4052 and EL-4080?
     
  4. makobuilders
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    makobuilders Member

    Yes the two layers appear to be identical and the resins are standard polyester resins. I've done some comparisons to other commercial fishing boats of 56-60 ton displacement (most are about 50 ft long) and although the hull thicknesses are about 1/2", on the bottom they generally are double that, to 1" thick.
     
  5. TANSL
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    TANSL Senior Member

    Perhaps helps the attached table. It is the dry fiber thickness without resin. Fishing vessel 25 m LOA.
     

    Attached Files:

  6. makobuilders
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    makobuilders Member

    Your table seems to indicate somewhat similar scantlings to my vessel. What would the "dry fiber" thickness equate to with the resin? Is it about double?
     
  7. TANSL
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    TANSL Senior Member

    I could not tell how much thickness should be added by the resin, that depends on how the laminate is made. It is best that you use your experience in this regard. Weight yes you can think of a 50/50.
     
  8. Robjl
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    Robjl Senior Member

    layup?

    ...to work out a layup we need to know the following:
    Length waterline
    Moulded depth amidships (draft of canoe body)
    Max service speed
    Panel size (length and width...space between frames and stringers)
    even an educated guess needs these:confused:
    1000gm of glass with resin will finish about 1.5mm thick
     
    Last edited: Apr 24, 2016
  9. TANSL
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    TANSL Senior Member

    You are quite right, of course you would need to know all that but since we want to be perfectionists, we should also ask, among other things, items in attached list, as well as mechanical properties of the materials used and, importantly, composition of the various layers and percentages of resin.
    Sure there are more factors but right now I do not remember.
     

    Attached Files:

  10. SamSam
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    SamSam Senior Member

    No, it would pretty much be the same thickness but heavier. All that would happen is the air spaces in the "dry fiber" would be filled with resin. It wouldn't expand the thickness and it might actually make it thinner.

    Here's a chart that might help somehow, post #3, click on it a few times to make it readable...

    http://www.boatdesign.net/forums/fiberglass-composite-boat-building/fiberglass-thickness-8686.html

    I'm thinking "scantlings" refer to the frame of the hull and what you are talking about is the "skin" which the scantlings (frame) support.

    We used to build 30' x 12' powerboats with about the same skin thickness that you're talking about for a 70' x 15', so to me it seems that layup schedule you posted is pretty minimal.

    I don't think you can figure out a skin thickness without knowing what sort of framing supports it or it's final shape.

    Is this a boat you're going to build? What is the reason you're inquiring whether the "scantlings" are right or not?
    [​IMG]
     
  11. makobuilders
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    makobuilders Member

    So the builder's hull layup of 12,300g seems to equate with their stated thickness of 10mm.

    I agree that 10mm on the bottom and 8mm on the sides sounds way too thin. It probably serves THEIR SOR but not necessarily mine.

    I have the detailed fiberglass layup schedule but nothing about the construction details so no info on frame and longitudinal spacing.

    Yes this information is based on a preliminary proposal received from the shipyard. Actually I'm impressed with their willingness to share information. Two other yards I have already eliminated, based on my gut feeling, because their attitude was the opposite, plus constant whining about how "expensive materials are these days."
     
  12. TANSL
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    TANSL Senior Member

    I think, at this point, you have no choice but to do the full calculation of the scantlings of the ship.
    We have given some guidance which naturally can not be applied directly to your boat. Now you must define the working conditions of the ship, design the structure (number and spacing of the reinforcements) and, only after all that, calculate layup and thickness of the plates and modules of reinforcements.
     
  13. makobuilders
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    makobuilders Member

    The layup appears to meet Chinese Classification, but besides the difference in density (300 versus 1600 g/m2) between these two fabrics, what is the difference in layman terms?

    And so if we wanted the hull to be built up thicker and stronger, would it better to specify more layers of just one of them, or just additional alternating layers as is currently specified?
     
  14. TANSL
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    TANSL Senior Member

    I fear that, given my difficulty with the language, I will not be able to explain so that you understand me. However, I'll try. I have developed my reasons and included as an attachment, not to bore other readers.
    I hope I've been helpful.
     

    Attached Files:


  15. makobuilders
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    makobuilders Member

    Thank you Ignacio for that detailed information. It cross-references well against other research I have been doing :)
     
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