Mat placement.

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, May 29, 2018.

  1. fallguy
    Joined: Dec 2016
    Posts: 5,067
    Likes: 948, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    if using 1708 or 1808 in a non-gelcoat foam build with epoxy; is there ever a situation where mat would be placed onto the core versus out?

    Would mat potentially improve or weaken the structure?

    Say
    1708-core-1708 (mat out)
    Vs
    1700-core-1700
    Vs
    1708-core-1708 (mat in)

    I am only familiar with mat out for print through w/ gelcoat, but someone told me mat to core is also used. I didn't want to argue.

    Thanks for any
     
  2. TANSL
    Joined: Sep 2011
    Posts: 6,778
    Likes: 494, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The distribution of the stresses on a panel, in its thickness, ranges from a null value on the neutral axis to maximum values, tension or compression, on the outside. From this point of view (although there may be other considerations, as you point out) weaker materials should be placed close to the neutral axis.
     
    fallguy likes this.
  3. fallguy
    Joined: Dec 2016
    Posts: 5,067
    Likes: 948, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Okay, so I will run some tests mat in.

    Thanks!
     
  4. BlueBell
    Joined: May 2017
    Posts: 1,756
    Likes: 487, Points: 83
    Location: Victoria BC Canada

    BlueBell "Whatever..."

    I'm covering a solid foam blank on a skinny race boat
    by piling 1708 on 1708 on 1708, etc with differing lay-angles for more multidirectional strength
    and at varying thicknesses depending on point loading.

    I'm interested in your tests.
    TANSL is correct in theory of course but I bet you won't measure the difference.

    Standing-by
     
  5. fallguy
    Joined: Dec 2016
    Posts: 5,067
    Likes: 948, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    The only thing I don't like about mat is the snakiness of biax can be an advantage at times, other than the obvious weight issue.

    For the mat; I expect the mat to be 3oz heavier per sqft. when two sides, or for say a 400sqft area; 75 pounds more.

    It would need to be stronger to justify that amount.

    It'll be a few weeks before we get any numbers, but I will report them here.
     

  6. TANSL
    Joined: Sep 2011
    Posts: 6,778
    Likes: 494, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The thickness is not as important, although it is, as to check that none of the layers supports a tension / compression higher than the admissible. It is interesting to note that a laminate of a certain thickness can be more resistant, more suitable, than another of greater thickness.
    That is almost correct but over time, and depending on the circumstances of use, the difference could be dramatic. And, in this case, it is not more expensive to do things well.
     
    fallguy likes this.
Loading...
Similar Threads
  1. Islander11
    Replies:
    14
    Views:
    38,314
  2. motorbike
    Replies:
    11
    Views:
    607
  3. Mark C. Schreiter
    Replies:
    33
    Views:
    2,573
  4. Gasdok
    Replies:
    3
    Views:
    517
  5. Robinfly
    Replies:
    4
    Views:
    889
  6. mizkuzi
    Replies:
    3
    Views:
    752
  7. atengnr
    Replies:
    46
    Views:
    2,280
  8. John Sakovits
    Replies:
    7
    Views:
    741
  9. Mike Inman
    Replies:
    14
    Views:
    1,623
  10. CloudDiver
    Replies:
    14
    Views:
    2,978
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.