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smccormick

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Posts posted by smccormick

  1. I'll take a stab at this since no one else has yet.

     

    I don't know what is sufficient for the application because there is no application information... Then I still probably wouldn't.

     

    CSM, as a mat, usually has a binder that holds all the pieces together and the binder is dissolved by styrene, a product not contained in epoxy.  Therefore the binder is never dissolved using epoxy and the fibers never come loose to make fitting work.  There is also some sizing compatibility that causes the resin/fiber bonding to be less than designed.  Stitch mat and some combination products don't have that problem because they're not glued and are therefore compatible with epoxy.  Most combination products that my supplier provides are epoxy compatible.

     

    I don't think you will see a big difference laying 1208.  It's a little bit stiffer but harder to pull out of shape.  

     

    Can you use 1200 where 1208 is specified?  I had this discussion with Graham.  I heard from others in the business that combination textiles are hold overs from polystyrene products and the mat has no place in epoxy construction.   Graham's response was that while it's true that you don't need the csm for peel strength, it does help getting glass fibers packed closer together and it provides some off axis strength.  But in the end he said that if the csm offends me I could use 1800.

  2. Thanks Gents.

     

    I was just reading through the first few pages of this thread, oh how optimistic I was at the beginning.  Thought I would be done in 1.5 years.  Two years ago the wife asked how much longer? a year?  I had some smart arse retort like "it better not take that long!"  OH, the fantasy.

     

    Whisky (just got back from Scotland and was taught the correct way to spell it) plank was over 3 years ago.  That means I've been sanding for 3 years and I still have more to do.

  3. 10 hours ago, Designer said:

    ... life is too short for that level of detail.....

     

    I try to tell myself that.  In fact, I started to clean up the sole of my build a week or so ago and started with the attitude of "it's a walking surface and will have non skid on it so I'm not going to put much effort into fairing it".  Didn't last too long before I had the long board on that too.  I know myself, if there is one thing out of place in the finished product, I will have to look at it every time I use the boat and berate myself for not addressing it.

     

    Who's the smarter man, the one who is playing with his boat or the one who is still sanding it 3 years later.

     

     

    • Like 2
  4. I almost always glass for waterproofing. I can laminate one layer of 10oz cloth instead of 3 coats of resin and I think it provides a more consistent, dependable thickness.  Of course adding glass comes with a small weight penalty.  E-glass has a specific gravity of 1.99 and resin 1.18, so at a 60/40 resin to glass ratio there would be a X27%X (came back and read, actually it's only 21.5%) increase.  But at 0.017" thick, I don't see it as significant.

     

    https://www.westsystem.com/products/compare-epoxy-physical-properties/

    https://en.wikipedia.org/wiki/Fiberglass

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