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.
 

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.
 

Assembling on the strongback