a center line lengthwise on the ply sheet at 24”. Also a center line width
wise at 48”. (This is where the center frame falls.)
the 12” x 32” triangles on the corners of the ply sheet, then cut, and set
and cut out the frame gussets and breast hook from the other corners as shown in
the drawing. (Making full sized cardboard patterns can be helpful.)
a 3” strip off both sides - one will make the lengthwise butt block for
glueing the bow section of the back. The other will be laminated into a backup
plate for the leeboard.
glue the triangles to the end of the ply per the drawing and instructions below.
fit the bottom:
Set the bottom on align the bow triangle and
the center line of the stern with the center of the transom. Weight it in place,
and tack it to the stem, frame and transom with finishing nails. How’s the
fit? If it’s good congratulations! If not, aren’t you glad the transom is
only dry screwed on…;-) If
necessary the position of the transom can be adjusted slightly.
When the fit looks good trace where the sides touch the bottom. Remove the bottom and cut outside the line with your circular saw set shallow. How close you saw to the line will depend on how you intend to remove the overhang. If you flush trim with a router it doesn't much matter. If you intend to hand plane and sand, you might want to angle your saw blade 18 degrees and stay pretty close to your line. This will give less material to remove later.
With the bottom removed, disassemble
and reassemble the sides, frame stem and transom – this time with glue. Pull
the string and check alignment before the glue sets up. Correct if necessary.
Next I'll position these on the bow and mark them for gluing the butt blocks.
I once again stapled over twine which works well. I did pre-bevel the butt blocks this time using my band saw and belt sander, which seems easier than sanding the taper after they're glued.
After the back is glued up, it is dry fit and marked at chines. Make sure the boat is aligned before you mark the back. A string pulled tight from stem to stern should cross the center line of your frame. If it doesn't nudge the hull around until it does.
The back is trimmed a little outside the line with circular saw. How close you cut it depends on your confidence and what tool you will do your final trim with. If you flush route like I do, it's not too critical. If you'll take the overhang off with a hand plane and sanding block, accuracy cutting this line can save work. Some folks even tilt their saw blade for this.
This reminds me of a great Yogi Berra quote I got from Lew Clayman.