Building the backbone: The Keel

The keel on this boat is a plank of 1" thick plywood with a rolling bevel along the edges.  It's sort of an unusual arrangement that is specific to this kind of boat so I wont get too technical but here's the basics.

I had to laminate two layers of 12mm plywood to achieve the desired 1" thickness.  This also allowed me to increase the overal length beyond the original 8' length cut from the standard sized plywood sheets.

The plans provide offsets for the keel.  At each station it indicates the inboard and outboard width, I marked both on the keel at the correct intervals square to the centreline.

By hammering small nails into the inboard marks I was able to bend a wooden batten through the points and scribe the outline.

The keel is sawn and sanded down to it's inboard outline.  It kind of looked like a surfboard at this point, progress?

The outboard outline is marked using the same method as before.  The rolling bevel is created by imagining a straight line cut from outboard line to inboard.  This was a huge amount of material removal done with a hand plane, beltsander, and oh so many blisters. 

Testing the bevels.  A rolling bevel means that the angle smoothly changes as it sweeps around the edge.  There will be some fine tuning later as well.

Cutting the bevels on the keel was definetely the most physically challenging part of the build to date.  I learned that the plywood is pretty rough on blades and sharpening was required often through the process.   Ultimately, the plywood planking must fall on the bevel and glue tightly so expectations are high but overall I feel like my accuracy is pretty good. Time will tell...