Builders' Forum Archives
Tips on Building a Kayak
Posted by Frank Grimaldi on Nov 6, 2006
Tips on building a CLC Chesapeake 17LT (and other CLC Kayaks)
I recently completed my first kit built kayak. Being an engineer and a contrarian at heart, I made a few modifications to the CLC building procedure that I think made the kayak easier to build, and nicer in appearance. The ideas presented here are not a complete assembly procedure but enough information is provided to pick up and run with it if you like the idea.
1. The plywood panels, as received from CLC had scarf joints that were not finely feathered, but the best that can be done with a CNC machine. The defined edge at the scarf joints can be improved by finely feathering this edge by hand (I used a Shinto rasp). Place the panels show-side to show-side. The final glue joint is much less obvious when the boat is later varnished. 2. Using my home's wood deck solved the problem of finding a location that was both true and long enough to epoxy the scarf joints on the side and bottom panels. The wood deck allowed me to strike a string line and hammer a few nails in place to ensure the correct alignment of the panels. (Please note that the CLC drawing for the Chesapeake 17LT omits the dimension from the string line to the side and bottom panels at the scarf joints. This was brought to the attention of CLC. Check with them it obtain the correct dimensions.) 3. When assembling the bottom panels to the sides, including the tightening of the wires, rather than suspending the hull upright as shown in the manual, I completed the whole task with the hull upside down and placing it on level saw horses. The horses were placed approximately 18 inches from the bow and stern. I also clamped the sheer clamps to the horses to ensure that the hull would not twist. 4. Before initial assembly of the kayak, I knocked off the sharp inside edge of adjacent panels where they meet. I also cut 1-inch lengths of ½-inch dowels, drilled a hole through the diameter and inserted the copper wires. These wires, together with the rounded edge produced a better alignment and less epoxy showed on the outside of the panels. 5. After aligning the panels and tightening the wires, I placed a small dab of thickened epoxy between each wire on the inside of the hull. This tacked the panels together and allowed me to remove the wires and dowels resulting in no copper showing on the outside of the hull. After curing, I then filled the outside groove between all panels as well as the wire holes. 6. I postponed permanently installing the bulkheads until later in the assembly process. After the epoxy on the outside cured, I custom fitted the bulkheads. I then inserted a temporary spacer at the bulkhead locations and used hot melt adhesive to keep them in place. I then removed the bulkheads. 7. With the inside of the kayak clear of the bulkheads, I was then able to filleted and glass taped the joints at each adjoining panel in one continuous installation. After curing, I installed the 6-oz glass cloth adjusted its width to extend about 1-inch beyond the bulkhead locations. 8. I installed the bulkheads, adjusting their shape to account for the fillet and tape at the joints. I also tacked these in place prior to filleting, thus eliminating the unsightly holes in the side panels. Hold off coating the inside with epoxy until just before you install the deck. This saves cleanup and touchup if you tend to be messy. 9. Rather than install the foot braces with the screws provided, I instead, made a wood plate, 3/8-inch thick by about 1-3/4 inches wide to which the adjustable foot pads would be mounted using #10 flathead screws. These plates were epoxied to the side panels. Before installing, I put a curve into the wood plates so that they would match the curvature of the side panels. This was done by placing the plates show-side to show-side with a small ½-inch thick block in the middle and then clamping the ends. I soaked them in water overnight and then placed them in a 200-degree oven for 4 hours. This adds a little weight but it is an acceptable tradeoff for a better appearance. 10. I found that installing the deck would be problematic when trying to get a uniform curvature and a close fit at the sheer clamps. To overcome the difficulties, I installed 2-additional permanent deck beams using a single layer of ¼-inch plywood epoxied in place. These were mounded at the aft deck location. I also installed 3-temporary deck beams, one aft and two forward. I used hot melt glue to mount them on the sheer clamps and also installed support braces mounted to the side panels and deckbeams. The exact locations depend on the area of the panel that is identified as potentially problematic during the test fit and also, taking into account, the location of the future hatches. I removed the temporary deckbeams after the hatches openings were cut. The hot melt glue is easy to remove with a small dull metal putty knife (spackling spreader) 11. Before attaching the deck, it is a very good idea to do a dry run first. Position the decking carefully and clearly mark its final location. Scribe a line around the perimeter of the topside (side panels). Then cut off the extra, but leaving about ¼-inch. With more that a ¼-inch of overhang, you are likely to create more curvature than specified and you may loose contact between the decking and the deck beams and bulkheads. To achieve a uniform curvature of the deck I placed strips of 1-inch webbing (rope will also work) around the hull and deck at each deckbeam and bulkhead. I used the tourniquet method for tightening the webbing. I also made a web-tightening device that is adjustable and could be used to assist in fitting the deck in the areas between the bulkheads and deckplates. The design is too complicated to describe here, other that to say that it was made from a 2x4 with one corner rounded and 5/8-inch holes drilled to accept the webbing and to allow for webbing length adjustment. Be careful and not over-tighten the webbing or you may decrease the radius of the deck. When tightening, push down on the deck at the deckbeam and bulkhead locations to be sure there is contact and that there is no gap at the sheer clamp locations. One more point, don't put epoxy on the tops of the bulkheads or deckbeams at this point. In the event that the webbing causes a distortion in the decks that distortion will remain after the webbing is removed. I think that is better to let the decks relax and find their natural shape and fillet the remaining gap later.
General Information 1. For maximum adhesive strength, always apply a thin coat of unthickened epoxy to the joint before applying thickened epoxy. 2. For the end pours, to reduce weight, mix in some Styrofoam. You can use the Styrofoam shipping peanuts that CLC sends with its packages. Take the peanuts and place them in a food processor to break them up. Add a very small amount of water if you want a smaller particle size. Use a mixture of epoxy, wood flour and dry Styrofoam. Mix it to a very thick paste, and then add a little denatured alcohol (not lacquer thinner) to make it pourable. 3. When glassing the kayak and when making the fiberglass/epoxy overlaps, to make sanding a featheredge easier, wait until the epoxy partially cures to the point that it is tacky but still pliable. Cover the overlapped edge with wax paper and smooth out the fibers with roller and/or your finger. The wax paper may stick, but you can remove it later when sanding. 4. When applying epoxy, an excellent tipping tool can be made from a short nap (fiber type, not foam) phenolic roller cover. Cut the roller cover in 3" to 4" lengths and then the cut each piece into thirds, lengthwise. Make a handle using a ¾"x1"x7" length of wood. Cut a diagonal slot at one end to accept the roller piece. Add a screw to hold the roller cover in place. The roller section also works better than a bristle brush or a foam brush when varnishing flat panels. Foam or a fine bristle brush, work better on curved sections when varnishing. 5. As an option, I added ¾"x1/8" strips of walnut on the perimeter of the deck to cover the hail heads. I also added walnut strips to the center portion of the hatch covers and replaced the plywood for the cockpit combing with 1/4 x3/4 inch walnut strips glued together and later cut to match the shape of the plywood combing. I solved the problem of holding the strips while the epoxied cured by nailing them in place using ¾-inch small diameter brads. However, to allow for the removal of the brads, I cut 3/8"x3/8"x4" strips of solid wood (not plywood) covered the underside with masking tape so the would not stick and predrilled a small hole in the center of each strip. After the epoxy cured, I used a chisel to split the wood. The head of the brad will be ¼-inch above the walnut, making for easy removal.
As a point of information, if you use ¼-inch thick solid walnut for the cockpit combing, you will have to reinforce the underside of the overhang where the grain runs approximately parallel to the gunnel. If you don't reinforce this area, the wood will likely split when pressure is applied (e.g. when you get in or out of the cockpit). I used 4mm plywood that was custom fitted to match the curve, and left it about a 1/8 inch short of the outside edge. 6. To fill the holes in the walnut, I made some walnut wood flour using a belt sander. I mixed the wood flour with epoxy and filled the holes. The match was perfect. 7. If you are varnishing your kayak and if you want a real high quality glossy show boat finish then sanding and buffing is required. The procedure that I used is: a. After applying 6, 7 or more coats, wait 4 to 6weeks, then dry sand with 400-grit dry paper. Dry sanding allows you to see all the imperfections. b. Wet sand with 400-grit wet or dry paper. c. Wet sand with 600-grit wet or dry paper or you can dry sand with 000 steel wool d. Wet sand with 1200-grit wet or dry paper. e. Using a power buffer with a lamb's wool pad and 3M Perfect-It II compound, buff the surface. f. Repeat with 3M Finesse-It II compound
This may sound like a lot of work, but it really isn't, especially considering how much work you have done to this point. It goes quite fast and, more importantly, the resulting finish will be nearly a perfect fine furniture finish. 8. A money saving tip… West Marine has just started selling its new Five Star Premium Varnish. This product is identical to Epifanes' Clear High Gloss Varnish and is less expensive. It is one terrific product.
I hope that these tips prove useful. If you have any questions, please call me at 843-838-0822.