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Sunday, August 24, 2014

Kingfisher Drift Boat Build - Fiberglassing the Side Panels

Well, today's the day to start prepping for fiberglass and that means sanding the panels. I've got a good dust mask, fans blowing and my fine dust filter system running. The sanding part of boat building is something you better be ready for because there' a whole lot of it.

From the advise of Jason Cajune's instruction manual, I'm going to glass the side panels now while the panels can be laid flay on the work table. He advises that it is cleaner and easier and the glass job turns out better.

Things to Gather Up and Organize

  • 5" Random Orbital Sander - Check!
  • 5" Sanding Discs. 100, 120, 150 grit -  Check!
  • Vacuum - Check
  • A 17' x 60" piece of 6 ounce fiberglass cloth for the two side panels - Check!
  • Epoxy, about 120 ounces. Check!
  • Squeegee - Check!
  • Foam Roller - Check
  • Scissors - Check!
  • Random Orbital Sander!
Preping the Panels

Since I've built a table that is 5' wide and 16 foot long I'll be able to do both panels at once. For the Kingfisher only the outside of the side panels will be glassed. 
  • One of the panels will have to be helicoptered around so the two outside faces of the side panels will be mirror images. Bottom to the bottom or top to the top. The two bow profiles should be on one end together.
  • I'll need to separate the panels by about 1".
  • I'll need to make a final inspection of the scarf joints. If they are bumpy a good thing to do is to take a piece of plywood about 1/2" x 4" x 12" and glue some 80 grit sandpaper to it. Smooth out the joint by sanding back and forth across it. In my case I'm going to paint the exterior of the boat. Since we are working on the outside panels I can sand through the finish veneer if necessary to get the joint flat. This is very important as this scarf joint will remain a hard point in the hull when it is painted if you don't get it perfectly flat. I'll need to really take my time. I'll need to work my way done to 150 grit.
  • If during the sanding process the feather edges get broken off I'll have to fill them with Epoxy peanut butter and then re-sand.
  • Once the scarf joints are perfect, I'll need to sand the panel down to 150 grit.  
  • I'll blow off the sanding dust with compressed air and then vacuum them.
Time to Fiberglass

Now its time to roll out the six ounce fiberglass cloth.
  • Lay the 5' wide fiberglass sheet across the top of both sheets. Roll it out so it covers both panels.
  • With a sharp razor knife or scissors I'll cut the glass down the middle between the two sheets.
  • I'll then smooth out all the wrinkles using my hands
  • Start by mixing 30 ounces of epoxy. That will be 20 ounces of resin and 10 ounces of hardener. Apparently you can use a kitchen mixer paddle attached to a drill to help mix the epoxy. This should be done at slow speed. I'll do the final mix by with a stir stick.
  • Start by pouring half of the epoxy on each of the two panels ( half on one panel and half on the other). I'll leave the mixing bucket upside down  to drain on one end.
  • I'll start in the middle of one of the panels and use the squeegee to spread the epoxy back and forth across the glass working it into the weave of the fiberglass. I'll try not to stretch the fiberglass.
  • I'll spread the epoxy across the plywood from the center to the edges and not the long axis. Sprading it in the long axis may stretch the glass too much. This can cause bubbles.
  • A tip is to take your time and take care not to dump any epoxy goo off the edges.
  • The epoxy will start to make the glass clear and it will be easy to see when the glass is getting saturated. 
  • It is important to carefully work the epoxy goo out to the edges.
  • If bubbles start to develop, work from the middle to the edge and pull the bubbles out with the squeegee. 
  • The motion is referred to as a "Modified Waitress Motion".  Use this motion until all the epoxy is evenly worked into each panel. 
  • If necessary mix up more epoxy to saturate any dry spots.
Tip - Don't over do the Epoxy!
  • If the glass seems to be floating on a puddle of epoxy this is bad. Squeegee some of it to other areas. The first coat of epoxy is meant to adhere the glass to the plywood and just partially fill the weave of the fiberglass cloth. 
Decision Time - Flow Coat or Call it a Day

At this point a decision needs to be made, I can (1) do a "flow coat" of epoxy over the glass or (2) leave it overnight. The advantage of doing a "flow coat" is that it eliminates having to sand the panels after they have dried. Once the panels have dried you must sand them prior to applying another coat of epoxy.

If the decision is to "flow coat" them the panels must sit for an hour or so and when they get tacky to the touch the "flow coat can be applied.

How to "Flow Coat"

Things I'll need

  • Epoxy
  • 1/8" foam roller
  • Natural Bristle Brush or Foam Brush
How to;
  • The tack coat with the fiberglass needs to tack up a bit. It should stick a bot to your glove when touched.
  • When ready mix up about 8 oz. of epoxy and when mixed pour it onto the panel and use the 1/8" nap foam roller to spread it. 
  • Spread it thoroughly as you don't want it to be thick.
  • When spread "tip it" with the brush to flatten out the roller marks an get the epoxy to lay down smoothly.
  • Mix more epoxy and repeat until both panels are covered

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