Sorry I am so late to the discussion but I have not been closely following the forum since the shelving of my model making activities.
The 45 degree line, a common practice in drafting, is clearly the method I used to extrapolate my ASR63 body plan (bulkhead drawings) from the sheer plan (elevation) and Half Breadth Plan.
Even with a hard chine, I found it very hard to accurately place the chine, forward flare and aft tumblehome, to achieve the authentic shape of each bulkhead. I also found that with Paralex error, photos cannot be relied on to trace any accuracy either.
In the case of the MAIMI ASR63 the use of ASR63 dressed up as PT boats for McHales Navy with a similarity in the hull with the PT boats where the main difference being the chine line cause me confusion research. The ASR63 internal forepeak fit out would not marry with the PT boat forepeak due to the chine line difference.
If you have a plan view that a clearly shows the chine and the flare/tumblehome, verified with photos, bulkheads can easily be extrapolated but the use of a 3D CAD program would ease the process.
