Let me have another goes at it and try to put all the pieces together.
You need to divide the hull up into multiple surfaces. The stern suggests that this should be 5 surfaces (not including the transom).
The analysis here is to use the planking as the guide. Think about each outer plank face as a separate surface.
If you start at the sheer strake, you find that next plank down shares a tangent edge between the tow and that the two end edges at the stern form a tangent curve. Therefore they can be merged into one surface for simplicity.
You can see the same for the top eight strakes.
But between the 8th and 9th strakes, they share a common tangent edge but their ends are not tangent. Therefore a new surface starts there Two planking strakes (9 and 10) form that surface (#2).
Moving down to the lower edge of strake 10. You have surfaces that are tangent to it but not to each other. Therefore you have three potential choices:
- Make strakes 9-10(2) and the lower strakes a single surface, trim, and make the triangle a separate surface.
- Make the triangle (4) and strake 9-10 (2) a single surface, trim the bottom and have the lower strakes form another surface (3).
- Make all three separate surfaces.
Trying Option 1, you find that if you try to extend the aft edge such that it will form a continuous curve with the end of strakes 9-10 will give you a weird curve. Maybe you can get it to work but it will be a lot of trouble.
Trying Option 2, you find that this certainly works at the stern. You can just extend your frame curves for strakes 9-10 to the centerline. This might cause problems at the bow but in this area it works.
Trying Option 3, you find this works even if there are problems at the bow.
Continuing down, strake 11 has to start a new surface. Moving to strake 12, it shares a common tangent edge with strake 11 and the ends form a tangent curve. They can be merges as one surface. Continuing to the keel, all the remaining strakes appear to be mergeable in the same way.
This analysis just takes into account the stern. You would need to redo it, taking taking the forwards into account the same way as the aft edges.
This shape, as represented by the stern, should be doable in Rhino without a lot of problems. If you could do it with planks, you can do it in Rhino.