Coremat strength vs cloth

Discussion in 'Fiberglass and Composite Boat Building' started by mrdebian, Jun 22, 2022.

  1. mrdebian
    Joined: Apr 2021
    Posts: 53
    Likes: 4, Points: 8
    Location: Greece

    mrdebian Junior Member

    Hi all,

    I'm using the following layup schedule in some kayaks that I build.

    First layer 300gr mat
    2nd layer 300gr plain wooven
    3rd layer 410gr biaxial wooven
    4th layer 290 twill wooven
    Plus two tapes (one aramid, one plain) accross the hull.

    I would like to ask those with experience if It make sence to replace or alter the layup with coremat, let's say 1.4mm to maybe increase strength along with stiff plus save some extra weight?
    Does it make sense or is suitable just to re-inforce let's say the part of the hull that the paddler sits?

    I'm always talking about hand layup, not vaccum.
     
  2. TANSL
    Joined: Sep 2011
    Posts: 6,985
    Likes: 554, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    This comparative table will show you if the change you propose is interesting or not.
    upload_2022-6-22_21-8-15.png
     
  3. mrdebian
    Joined: Apr 2021
    Posts: 53
    Likes: 4, Points: 8
    Location: Greece

    mrdebian Junior Member

    TANSL, I'm not sure if I can understand properly the values. Is it the higher the better or the opposite?

    Thanks
     
  4. TANSL
    Joined: Sep 2011
    Posts: 6,985
    Likes: 554, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The greater the variables indicated, the better the material will withstand direct tension or compression. In this sense, you will be able to verify that the MAT 300 is around ten times more resistant than the Coremat XM10.
     
    mrdebian likes this.
  5. waikikin
    Joined: Jan 2006
    Posts: 2,410
    Likes: 165, Points: 73, Legacy Rep: 871
    Location: Australia

    waikikin Senior Member

    You'd best do some test panels to get a feel for use of the material and how it affects the properties.
    Generally coremat is placed within the laminate as a "core" to further separate or space the skins inner and outer apart. Looking at the current laminate it doesn't seem to fit that well. You might lower the gsm of the outer chop to 225 or eliminate it in favour of a surface tissue and alternatively use csm in the middle of the laminate. Coremat is not particularly light when wet out as absorbs/soaks a high percentage of its volume with resin, it also costs whatever it costs. The big advantage is that laminate thickness can be increased quickly and it's quick and easy to fit and conform, care must be taken to not scavenge resin from the substrate applied so backwetting best. It's great material if you want medium weight products in a reasonable time frame, much cheaper & easier than foam cores to install correctly, kind of a midway core between solid grp and lightweight sandwich. Many don't rate it and claim is rubbish, sometimes true when not applied or installed intelligently... same for any product. You might find ideal for some deck areas or whatever, just get some and try it out.
    Jeff.
     
    mrdebian and wet feet like this.

  6. KD8NPB
    Joined: Mar 2018
    Posts: 112
    Likes: 20, Points: 18
    Location: South Carolina

    KD8NPB Senior Member

    Coremat has very little strength in terms of tensile strength, it merely adds thickness at a low weight penalty.

    By spacing out the face and backer laminates, you increase stiffness.
     
Loading...
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.