Kleb's Custom Board Building: Inserts

Cutting the Holes (Pukas)

• Make four "woodies" from 1/4" some strong, lightweight material (e.g., fir or spruce). Woodies fit alongside of the boxes to help distribute loads. They are typically cut 1/4" deeper than the box, and 3" longer than the box. For example, if you have a typical 10-1/2" long chinook box, the woodies would be around 1-1/2" wide and 13-1/2" long. Round the ends of the woodies.
• Lay-out the positions of the foot strap inserts, the mastbox, and the finbox according to your measurements. Make sure the tail is thick enough to accomodate your finbox depth.

  

• Lay each piece in place and trace its outline with a felt pen.

  

• Use a router with a straight-cutting bit initially set to just cut through the glass. Route out the interior of each outline. For the finbox and mastbox areas, only cut the portions where the woodies will reside. If you are industrious or just nervous about making a mistake, you can make router templates to make this process less error prone.

  

• Reset the router depth-of-cut in several stages and work each area down to the proper depth. The proper depth is so that the insert is flush-to just proud of-the surrounding glass (<1/16"). In the case of a thin tail, the fin box woodie holes (and woodies) might need to be altered near the tail to prevent going through to the deck cloth.
• After the woodie slots have been cut to depth, cut the box areas as described above.
• If you've done the pukas without a router template guide, you can straighten the edges with a flat file.
• If you have a thin tail, and footstrap inserts are going to collide with the fin box hole, do not route the holes for the footstrap inserts until after the fin box is installed.

Installation

• Fin Box
  • Rough-up the outside of the fin box with coarse sandpaper and clean with acetone.
  • Put in an old fin or piece of wood and tape the rest of the box off.
  • Lay-out four layers of cloth so that when the fin box is inserted into its hole, the cloth stands-up about one inch on all sides.
  • Similar for the woodies, except use only one layer of cloth per woodie.
  • Tape off the deck around the finbox holes.

    

  • Mix about 6 oz of epoxy, then thin by 150 percent volume with glass microballoons. In other words, add about 9 oz of microballoons to 6 oz of mixed epoxy.
  • Fill the hole about one-third full with the epoxy mixture, painting the sides with a brush.
  • Pour the remainder over the four layers of glass, the box, the woodies, and their single layers of glass.
  • Wet-out the glass layers and paint the woodies and box with the epoxy mixture.
  • Place the four layers of glass over the hole and press the box and glass into place.
  • Repeat for the woodies.
  • Make sure that the glass extends above the surface of the board and that the box and woodies are pressed down firmly.
  • Also make sure that the fin is aligned with the centerline of the board and that it is perpendicular to the bottom. Use a piece of fiber-reinforced tape to hold it vertical once you have sighted it using a carpender's square held on a flat section of the board's bottom. Remember not to set it on the vee'd part if you have one.

    

  • Remove the masking tape and trim the excess glass after the epoxy starts to gel.
• Mast Box
  • Proceed as for the fin box, remembering that the opening usually goes toward the rear of the board and that it and the slot should be taped-off before proceeding.
• Footstrap Insers
  • Again, similar to the box installations above, except only one layer of cloth is necessary.

Capping

• Grind all the inserts until they are flush with the surrounding deck. I used an air file (straight line sander) with 36 grit paper, followed by a 6" orbital palm sander equipped with 60 grit. Also roughen an area to accomodate the capping (see following section). Remove the dust and wipe the areas down with a clean rag dampened with acetone.

  

• Fin Box
  • Fill the box with baking flour since we want the glass to stick to the top of the box, but not fill with epoxy.
  • Cut two pieces of cloth. The first should be a rounded-corner rectangle about 1" bigger than the woodies on all sides. The second should cover the entire tail area, tapering to a peak along the centerline of the board some 10 inches ahead of the leading edge of the woodies.
  • Tape-off the rails and top deck as appropriate. Mix about 8 oz of epoxy and wet-out the glass layers. If you want to avoid a lot of sanding, apply some peelply as was done in the laminating section.
• Mast Box
  • Again, fill the box with baking flour.
  • Cut two layers of cloth. As for the fin box, the first should be a rounded-corner rectangle about 1" bigger than the woodies on all sides. The second layer should overlap the first layer by an inch.

    

  • Tape-off the surrounding area and mix about 4 oz of epoxy and wet-out the glass layers. If you want to avoid a lot of sanding, apply peelply.
• Footstraps
  • Fill the insert holes with flour.

    

  • Cut a bunch of 5" circles to place over each insert and along the heal areas of the board. Also cut a piece of cloth that covers the entire rear of the board, ending in a reverse vee ahead of the mastbox. Refer to sketch.
  • Mix about 6 oz of epoxy and process to wet-out the glass. Peelply if desired.