FOLDING ONE-MAN KAYAK

08/23/99 rev 01/13/07

You asked me for the plans for our little fun kayaks that you saw us using and I gave you this address to a special section of our web pages. These little boats always attract inquiries and I've handed out, and mailed many copies of the plans, but no more. Since discovering the Internet, I don't do "snail mail".

The fractional age tyke, my daughter, is being taught to paddle by her big brother. She's a bio-chemist now, He's a corporate exec and the kayaks are still in good shape. Yes, they're used every summer and they've been patched with contact cement and canvas a few times and repainted two or three times.

I built the two kayaks that you saw about 1968 from plans that a friend had. As I recall, he told me that he acquired them personally from a manual arts instructor that was camping nearby on an Idaho Lake. My friend had built several of them a few years earlier, as had some of his acquaintances. The plans were battered, faded and even had a small section burned, but they were usable, so I built a pair as did other friends since. One of these good folks traced over the plans and retyped the instructions so we could share with others. I have scanned them in for you.

The designer, Jess Rathburn, published an article "Folding Kayak" in Popular Mechanics, June 1963. Someone in our crowd ran across it and gave me a copy a few years ago. It's clearly a very similiar to this, so obviously the design is in the public domain and I'm free to share it with you.

Following are two pages of plans and two pages of text. The text is nearly original, so ignore the estimated cost (VBG). I've added a couple comments, initialed WR, based on our experience. Good luck on the ten foot plywood- it can be hard to find. If you're interested in further info on folding kayaks, go to The Folding Kayak Pages by Michael J. Edelman.

Have Fun, Wayne Roderick

Plans, page 1 of 2

Page 1 of the Instructions
                                  FOLDING, ONE-MAN KAYAK


   Materials and methods developed from plans and instructions of Jess H. Rathburn,
   Co-ordinator of Industrial Arts, San Francisco Unified School District.

   This kayak weighs less than 40 pounds and will carry a full-sized man. It can
   be easily constructed with hand tools in a home workshop. Costs will vary between
   $12 and $20 depending upon materials used. This design is for a 10-foot model.
   The same basic principles have proven to be successful in 8 foot, 12 foot, one and two-
   man models. Everything is held together with contact cement; no nails, screws, or
   metal fasteners are used.

   MATERIALS

   Plywood:          Use exterior, good on one side, AC for lowest cost. Good two sides
                     or marine ply will greatly increase cost.

   Hardwood:         Philippine mahogany is cheapest and is very satisfactorv:

   Canvas:           Use 14 to 18 ounce material. Can be treated, but test to see
                     that contact cement will stick completely to treated material.
                     (RISKY!- the contact cemented joints started failing after
                     about a year on some treated canvas-  Use untreated -WR)
                     
   Contact Cement:   These vary greatly. Test on canvas and wood. The faster drying
                     the better. Be sure to follow special instructions given later
                     in using contact cement. (lnstruction #3)
                     (Use the real stinking stuff- modern water based glue is not
                      a good idea. Do it outdoors, in warm weather!!!! -WR)
 
   Paint:            Use durable exterior paints and varnishes. Over canvas the paint
                     must be a flexible type. Some paint solvents will lift the
                     contact. cement through the penetration of the vanvas. Reglue if
                     this occurs. An outside prime coat of 1J.P. Fuller's outside latex
                     water thinned primer is a good protection against this.
                     (Use only latex on the canvas and glue joints -WR)  
                            All measurements in inches

  *Top & Bottom                   4 pcs.   1/4 x 11 7/8 x 120 Exterior Plywood
  *Seat                           1 pc.    1/4 x 9        48
 **Back Rest                      1 pc.    1/4 x 9        14
 **Paddle Blades                  2 pcs.   1/4 x 8        15
 ***Spreader Boards               2 pcs.   1/2 x 11       24
   Paddle Bar-                    1 pc.    1 x 1          72     hardwood dowel (mop handle)
   Bottom Panel Inside Strip      2 pcs. 5/16 x 1/2       60     Philippine Mahogany
   Top Panel Inside Strip         2 pcs. 5/16 x 3/4       60
   Top Panel Cockpit Top Edging   2 pcs.   3/4 x 3/4      60
   Bottom Outside Runner          2 pcs.   1/4 x 1/2     117

   Canvas (allow 2 inch overlap on seams.  All sizes exact finished size) 3 yds. ·36" wide
   End Bias-Cut Strips            2 pcs. 2 1/2 x 46
   Edge Straight-Cut Strips       2 pcs. 2 1/2 x 96
   Center Top & Bottom Seam       1 pc. 10 x 16' 4"
   Back Rest Hinge                3 pcs. 2 1/2 x 6

   Contact Cement                 1/2 gallon  (Needed 2-1/2 qts- WR)
   Primer                         Sherwin-Williams Check-Guard  (Latex paint- WR)

  *Exterior Plywood               1 pc.    1/4 x 4'    x 10'
 **Exterior Plylwood              1 pc.    1/4 x 2'    x 4'
***Exterior Plywood               1 pc.    1/2 x 2'    x 4'
   Philippine Mahogany            1 pc.      1 x 6"    x 10' (preferred)'
                               or 2 pcs.     1 x 4"    x 10'




Page 2 of the Instructions
                            CONSTRUCTION PROCEDURE


 Cut Plywood
 1. Top - cut 2 pieces 1/4" x 11 7/8" x 10' from the 1/4" x 4' x 10' sheet of
          exterior fir plywood. Cut the 10" x 48" cockpit piece out with a sabre
          saw. Save the cockpit piece for a floor board.
     Bottom - cut 2 pieces 1/4" x 11 7/8" x 10' for the bottom.
 2. Each piece Should have a 1/2" straight section on the end. See plans - detail A.
 3. Plane or file and sand all edges round and smooth.

 Cement
 4.  Cement 4 pcs. 5/16" x 1/2" x 52" and 8 pcs. 5/16" x 1/2" x 5" on the inside of
     the top and bottom pices of 1/4" plywood. See plan.
 5.  Cement 2 pcs. 3/4" x 3/4" x 60" on the outside of the top pieces. See plan.
     See 9 and 10 below.
 6.  Lay out area to receive cement with Pencil lines 1 1/2" from the edges.
 7.  Apply top-grade contact cement with a cheap 1" brush liberally to both surfaces
     and allow to dry until paper will not stick to the cement.
 8.  Apply a second coat to both pieces and allow to dry until paper will not stick
     to the cement.
 9.  Bring the pieces to be cemented into proper position and squeeze them. (Clamps
     are not necessary.)
10.  Cover the joints thoroughly with many blows of a rubber mallet or block of wood
     and a hammer with the panels resting on a heavy bench.
11.  It may take 30 days for contact cement to reach full strength. Do not fold the
     kayak until the cement is thoroughly set after approximately 24 hours.
12.  Prime and/or paint the inside surfaces of all 4 pieces of plywood with two coats.
     Do not get paint on the outside surface before cementing the canvas strips in place.
     (Prime with Sherwin-Williams Check-Guard.)
13.  Assemble top and bottom in proper position using 3 1/2" spacer blocks. See
     plans - detail C1.
14.  Draw a pencil line 1 1/2" from the edge all around top and bottom pieces. Apply
     two coats of contact cement to this 1 1/2" edge area and to the canvas bias strip.
     See steps 7 and 8 above.
15.  Start in the center of the bias strips. Pull the strips taunt and bend simultaneously
     Cement both sides down evenly and roll the canvas down with a paper hanger roller
     first, then place it on a concrete floor and mallet the joints on both sides.
16.  Apply two coats of cement to the side edges and to the canvas side strips.
     Position-them properly, then roll and mallet in place. Allow to set for
     approximately 24 hours.
17.  Cut the spreader boards out of  1/2" exterior fir plywood. plane or file and
     sand all corners smooth.
18.  Cut the canvas center strip out of 14 to 18 oz. convas or #10 Duck (see sketch).
     19.  After end and side canvas strips are thoroughly set, set the spreaders in place.
     Mark the edges 1 1/2" in for cement. Then apply two coats of cement to the.plywood
     and canvas center strips. After it has dried, bring the canvas into position, roll
     it down and then mallet the joint tight all around. Start in the center of the
     bottom and work towards both ends.
20.  Allow the center strip cement to set for approximately 24 hours. Then collapse the
     kayak and cement the two bottom runners in place. Use clamps to hold the ends down
     tightly for a few days.
21.  Seal the canvas and all cement joints with an exterior latex water thinned primer.
     Note:  oil or solvent base paints may soften the cement joints. After sealing,
          the kayak should be painted with a good undercoat and then finished with
          two coats of marine enamel all over.  
22.  Cut the paddle blades out of 1/4" exterior fir or hardwood plywood and attach to
     a 1" fir or hardwood round. Use a good mop handle about 1 1/8" diameter for paddle.
     Obtain from industrial janitor supply.


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