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Saturday, August 30, 2014

Kingfisher Build - Laying Down Kevlar and Fiberglass on the Bottom

Laying Kevlar and Fiberglass on the Bottom

The Kingfisher is designed to have a 38" strip of Kevlar right down the middle on both the outside and the inside surface of the Plascore Bottom. This leaves about 10 inches on each side. It gets one full width layer of fiberglass and then in addition, 10 " strips on each side to reinforce the edges. When you put Biaxial Fiberglass tape on the chine you essentially have 3 layers of fiberglass on the edges. This layering happens on the inside and the outside of the bottom.

So a Simple Outline of the Process is;

  1. Pre-cut the Kevlar and Fiberglass mesh.
  2. Lay down a tack coat of epoxy and the lay up the Kevlar. 
  3. Lay a flow coat of epoxy over the Kevlar and lay down the 60" wide layer of fiberglass.
  4. Flow coat the fiberglass to fill the weave.
  5. Lay down 10" strips of  fiberglass on the edges to reinforce the outside edges.
  6. Flow coat over the 10" strips.
  7. Let this set up overnight and do the same thing on the other side.

There will be one 38" wide piece of Kevlar down the middle, one full width piece of fiberglass and strips at each side of the Kelvar to reinforce the edges. These strips will be approximately 10" wide. (57" - 38" =  9 1/2").  This makes up the thickness where the Kevlar doesn't reach the sides and adds strength.

And the More Detailed Explanation;

The Kevlar 

The first piece to go down is the Kevlar. Kevlar has a lighter specific gravity than epoxy  which means it will float in the epoxy. This is not good. In order to solve this issue, a tack coat of epoxy will be laid down on the Plascore bottom. A flow coat of epoxy will be laid down and then once it tacks up the Kevlar cloth will be laid down.

Kevlar Step by Step
  • Prior to laying down the tack coat, roll out the Kevlar on the dry Plascore bottom and cut it to length. The Kevlar will be approximately 12' long. Place the Kevlar centered on the sheet in both width and length. Don't cut the Kevlar to the approximate shape, just plan on letting it hang over the edges as it is applied. I made that mistake on the bottom side.
  • When the Kevlar is in position, make register marks with a permanent marker at the sides and the ends for reference. This is very important because once the tack coat is applied the Kevlar must be placed exactly and carefully where it belongs. Having help to lay the Kevlar is a great idea. I did it by myself and it was a PITA.
  • Carefully roll the Kevlar back up on a cardboard tube. Keep it tightly rolled as the will greatly help when rolling it back out on the tacked up Plascore. This was my lesson learned for the flip side.
  • Now it's time for the "tack coat". Mix up about 24 ounces of epoxy. I'd advise doing batches of 12 ounces each. You can apply the epoxy with a foam roller. This will spread it evenly. Basically like doing a "flow coat".
  • Make sure you overlap the register marks by a couple of inches.
  • This coat must "tack up". It should take about an hour at 60 degrees, more if colder, less if warmer. It should be sticky enough to grab a finger on your rubber glove.
  • Carefully unroll the Kevlar down the length of the bottom. Try to lay the Kevlar along the register marks. Try to get it as straight as possible but it is more important that there are no bubbles underneath. This the PITA part.
  • Smooth it out with your gloved hand as you unroll it.
  • Once it is laid, press it down firmly into the panel with your gloved hands to ensure it sticks down and does not float up.
  • Wait about an hour and then spread another coat of epoxy, This will be a flow coat. The goal is to fill the Kevlar weave. Spread the Flow coat as evenly as possible with a squeegee.

The 60" Fiberglass Mesh - Now it's time to lay down the full width layer of fiberglass cloth.

60" Fiberglass Cloth Step by Step
  • Lay down the 60"wide  layer of fiberglass over the entire panel, covering the just flow coated Kevlar. Smooth it out with your gloved hand or a squeegee as you unroll it.
  • Add another coat of epoxy, probably about 42 ounces, to completely wet out the glass. Use a squeegee to smooth the cloth and eliminate wrinkles and bubbles.

10" Strips of Fiberglass Cloth.

You will have a layer of Kevlar with a layer of Fiberglass laid down at this point, The Kevlar area will have two layers and the outside strips will have one layer of fiberglass. The next step will be adding a 10" strip of fiberglass over the single layer at the edges. This reinforces the 4 1/2" Plascore strips that were added to each side of the 4x8 sheets.

10" Strips Step by Step:
  • Lay the 12" strips of glass cloth on the edges.
  • Flow coat epoxy over the strips and smooth them out with a squeegee.
  • Once this is all done, place 3 mil plastic over all the joints in the Plascore sheets, (the dovetail joints and the side strips).
  • Then place plywood or boards over the joints and weight them heavily until the epoxy is cured overnight.

OK, One side is done. Next up the Other side.

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Have any Questions or Comments? Let me know, Clay.