Cutting Out Cross Sections

hdpe-cross-sections-16Use a jig saw and smooth cutting wood blades. HDPE is easy to cut and standard wood blades will last quite a while. Cut along the concave lines created using the flexible cable and permanent marker. The original deckridge lines are used except at the gunwales where the line flare out . The extra HDPE next to the each stringer holes, strengthens the stringer to cross section connections. Next, the hole cutoff area will be removed.

The hole for the inwale has been drilled in this photo. It is located 1.5″ center to center from the gunwale. It is centered on the line between the gunwale and keel.


Hole Cutoff – Cut along the cutoff line to create the “snap-on” connections. The opening is now 1/2″. The center line “permanent marker ink” has been removed with a paper towel. If the lines prove difficult to remove, wipe them off using MEK.

Note – There is excess HDPE at each cutout. This material adds strength to the these area. After the frame is completed, each cutout area will be rounded with a file to create a smooth transition for the PVC skin.


Center Cut – Mark the center of the cross section for cutting. Allow 3/4″ to 1″ between the stringer holes and the inside line, and between the outer and inner edge. See photo for reference. The inside holes are there to smooth out the transition wherever two lines intersect. It is not necessary to do this as the line can be cut entirely by jigsaw. Note the line at the inwales. They must be 1/2″ from the inside edge of the holes to permit “snapping-on” of the inwale tubes.


Finished cross section – The outside and inside edges of the cut surface should be filed and sanded to smooth out the edge. No sanding or finishing is required on the surface of the HDPE. The “snap” connections between the cross section and stringers may require additional attention.