Making the centerboard

One of the first things I'll have to do once I've finished assembling the building frame and laying out the bottom (garboard) plank, is cut a hole for, and set up the centerboard. For those who aren't sailors, the centerboard is Navigator's primary "keel". It's essentially a retractable wing that provides lateral resistance below the waterline for wind pressure on the sails above the waterline. When wind fills the sails, from the side of the boat, the centerboard will stop the boat from slipping sideways through the water, and channel the energy by providing a hydraulic version of "lift", and help the boat move forward through the water. 

So it's a critical part of the construction. I've chosen to make the centerboard out of a laminated pine blank, coat it in epoxy and sheath it in fiberglass.  It has a very specific shape defined by something called a NACA profile. I made a template out of scrap plywood, like Robert Dieterich did for his Annie build. See his blog for photos. This was used to channel out the general shape of the foil. I then used power and hand planes to shape the board down to the router cut-lines. 

Once the board is finished, it will be "housed" in the centerboard trunk, which is exactly what it sounds like: a box (waterproof) that the board can be retracted into for downwind sailing, or beaching and trailering the boat. 

Laminating the centerboard blank

This is a full-size template for the NACA foil shape. Effectively a horizontal cross-section of what the centerboard should look like.The finished side will be the smaller foil in the inside right. The rectangle is the blank shape. The larger outline is the offset for the router template I made to guide the initial shaping/carving of the blank.

The roughed out centerboard. You can see the pivot hole a the bottom (top) of the board. The rounded rectangular protrusion will be where the up-haul pennant shackle gets attached for raising and lowering the board during sailing.

Roughed out board

Carving out the pennant shackle attachment point

Back side shot of the same area

Front top view of the board. You can see the blade shape emerging.

Cutting and shaping the sides of the centerboard trunk.

The "hump" at the front end of the case accommodates the radius of the pivoting board and holds the elevated pennant shackle block.