Building a Jarcat 6 - Part 1
Frame 2
Now it was onto making the frames. These were laid out on 6mm plywood and then cut out with a jigsaw. Edge timber of cedar was epoxy glued as shown in the plan. When the glue had set stainless steel screws were added as a mechanical joiner.

 The centrelines and waterline were marked on both sides of all frames to assist in placing them on the strongback.

 Notches for the stringers, chines, keels etc were marked onto the completed frames and cut out, once again using the jigsaw. After blunting one timber blade I switched to a high speed steel blade which handled cutting the epoxy glue better.

 All frames were then given a coat of epoxy resin with TPRDA added. This additive helps the epoxy penetrate the timber and protect it from rot.
Stacks Image 37
Frame 3 - Note the greaseproof paper under the edges to stop epoxy sticking to the supports
Stacks Image 40
Rim pieces for the bow of each hull
Stacks Image 46
Having prepared all the frames, stems and rim pieces the next step was to assemble them on the strongback in the positions shown in the plan.
There is a 200mm overhang at the rear of the boat - I found that I had left 180mm to the face of the roller door when it was closed so Marg and I had to move the strongback forward in the carport!!
 
The assembly of the frames on the strongback was straight forward - except for frame 4. This frame has a 10 degree slope and when I tried to mount it to the strongback rails I found that the supports would not meet the frame. I improvised and you can see how I mounted this frame in the picture.
Stacks Image 49
The frames were erected vertical using a "Smart Level" - this is a level with an inbuilt electronic sensor and display. It will display in percentage and degrees (handy for checking frame 4).
I used fishing line tied to a nail at the front and rear of the strongback to set the centreline and the frames were aligned along this line.
 
The stems were glued and screwed to frame 1 and the rimpieces.
Stacks Image 1
Having set all the frames to line and vertical (except frame 4 of course) I next added the gunwales on both sides of the boat.
Next the 20mm by 20mm stringers were added to both the outside edge and the botttom of each hull. Gluing these into position sets the spacing finally and checks and cross checks were made to ensure both the correct spacing , squareness of the frames and their verticality.
 
To assist in obtaining the correct curvature for the bottom stringers I cut frame 2 from 18mm plywood and assembled temporarily onto a piece of pine at the correct height. The stringers were not glued to this frame at this time.
Stacks Image 4
Having frame 2 on the temporary support proved helpful when assembling the keel onto the frames and stem. The stringers provided enough downward resistance that no further weights were necessary to maintain the correct height.
There certainly is some pressure required to bend the keel across frame 1 and along the stem. I added extra weights ( concrete blocks) to the front of the strongback to ensure nothing 'moved'.