The position of the notch for the bottom plank on the stem drawing is given as 674mm. Assuming that:
1. The drawing indicating the relative frame positions for all frames is correct and
2. The centrecase is correctly placed at 1775 from the end of the bottom plank but also 810mm behind the forward face of the mast per sheet 3/12 and
3. The stem governs the position of frame #1 physically because the laminated 12mm sides end where frame #1 starts
... then by my estimation, the notch dimension is about 15mm too far forward (or short)on the stem drawing.
This means that when the stem is correctly positioned on the bottom plank, there is a 15mm gap between the end of the 12mm ply bottom plank and the stem notch transition.
This is best illustrated in the picture above.
Having matched the curved profile of the stem to match exactly with the profile of the bottom plank, I was able to bond the 20x20 doublers to the stem before assembly to the bottom plank.
However, the transverse limber hole in the stem at frame 2 creates a break in the doubler and as a result I got the break in the wrong place because I followed the stem drawing alone. In the picture below, the stem doubler was chamfered to line-up with the limber hole in frame #2 which is now correctly positioned forward of the mast. Not a serious thing but it would have been nice to avoid the confusion.