Building a Cedar Strip Kayak: The Details: Making and Setting up the Forms

Author:
jimmar
Updated:
Mar 28, 2020

My first cedar strip kayak waiting one morning of my solo trip.

building-a-cedar-strip-kayak-the-details-making-and-setting-up-the-forms

Tracing the Templates

Once the templates are made for each half form they need to be traced on to plywood sheets. A baseline and center line is drawn on the plywood. The form is tacked down aligned with the center line on the plywood, traced, then flipped to the opposite side of the center line and traced. You can fit several forms on a sheet of plywood, by re-arranging the templates to fit. For convenience of attaching the extensions the water lines were also drawn onto the forms.

scrap wood from an old computer desk and shelving unit

A Word About Wood for the Forms

Particle board with ½ inch thickness is a good choice. MDF could also be used. I chose to use particle board that I salvaged from an old computer desk. The sheets varied from ½ to 5/8 in. thickness. I used the thicker boards to lay out the forms that are nearer the center of the boat. Salvaging material saved about $20.00. The extensions were made from old pine 1X12 shelfing.

Cutting the Forms

I used a jig saw to cut the forms. A band saw would be preferred but I do not own one. I cut just outside of the lines and sanded the edges smooth and square with a drum sanding bit in my drill press. Onto the drill press table, I clamped a piece of particle board with clearance hole cut for the sanding bit. A notch (3/4 x 7/8 inch) on both sides of each form was cut at the sheer line for the sheer clamp (covered in a a future hub).

The stern and bow stem forms have 1-1/2 holes drilled about 2 inches apart along each edge to allow for clamping the stem laminates.

Mold Extensions

Next I cut more scrap wood for mold extensions. These were attached to the molds at the eight inch water line. Their purpose is to securely hold the forms above the build table once they are attached to the station blocks on the build table. My extension pieces were about 6 inches high with width that varied between about 3 to 10 inches. The extensions were clamped to the forms and the forms and an outline was traced so I knew about where to drill clearance holes for screws in the extensions. Once the holes were drilled the extensions were again clamped to the forms and attached with drywall screws.

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Making a Build Table

I saved some money here again by making a build table from a single sheet of ¾ inch particle board. The scrap left over was a piece about 3 X 3 inches. The table top was 12 in wide by 16 feet long. The bracing was 3 inches inches. The table is constructed in two pieces with center piece that slides between the bracing sections. Once all the pieces were cut from the plywood the table was assemble and placed on a couple of saw horses. I added some bracing to the saw horses and a set of make-shift legs to the center of the table. The whole thing was checked for level and adjusted with shims where needed. A center line was drawn the length of the table on its top.

The Station Blocks

The molds and extensions are attached with screws to 2x2 blocks which have been screwed to the build table at one foot intervals. The block for the mold in the center of the kayak is attached to the table offset by the thickness for the form so the middle of the form thickness is exactly center of the table. The blocks towards the bow are on the stern side of the one foot lines. The blocks toward the stern are attached on the bow side of the one foot lines. The forms/extensions towards the bow are screwed into the blocks on the bow side. The forms toward the stern are screwed into the blocks on the stern side. The form closest to the bow and form closest to the stern are first attached and a line (I used black braided Dacron fishing line) stretched in between them from a small nail in a block of wood screwed near the top center of each form. Each from is first clamped the station blocked with its center line aligned to the center line on the build table and the line stretched at the top. Check the form placement by sliding a long strip of wood along the sides over the entire length of the kayak. The strip should touch each form with little or now gap or bulge. I found one form at station number three that had about a 3/8 gap between the strip and the edge of the form. There was an error somewhere in the process. It was corrected by moving the station block forward until the gap was gone. Once the forms are in place a long thing strip of wood is stapled at the top of each form, while checking for level on the vertical of each form.

The stem molds are attached such that their tops are 1 inch below the top of the forms they butt against to allow for the thickness of the inside stem. This required an extension on the bow form to get the proper height. The stem forms are held in place with guides on either side made from scrap wood.