How about CAD? Card Aided Design? Either transfer the tape template to cardboard for final fettling, or start with card in the first place?
That is right.
Use either thick paper or cardstock (better) to make sure the template actually follows the curves in the shape of the hull: tape will not curve smoothly over the empty space between your frame (for POF) or bulkhead (for POB).
Describing how to do this in words is difficult: that is why I posted the video.
We will try anyways:
Start by cutting out a paper template of the full size plain rectangular plank (dimension of the actual plank).
Then:
Step 1 dry fit the paper/cardstock plank onto the model and follow the horizontal portion of the rabbet in the keel. Where the curve begins, at the foot of the stem, you will likely notice that the paper will twist (up) a bit and that is ok, The twist should begin slightly back from where the curve begins at the foot of the stem, at that point, just bring it / force it back down to draw the curved area.
If you just keep the template as is, you will end up with a wood plank that is not straight on the top edge: and it should be.
Step 2 draw the curve on the template to follow the rabbet at the foot of the stem.
Step 3 Remove the paper plank template from the model and cut the curve. When you put the cut template back onto the model, you will see that the plank is too short (because it naturally twists up) and that there is now a gap between the edge of the plank (curve area) and the rabbet towards the foot of the stem.
Step 4 place the plank in position onto the model: dry fit the template on the framing and into the keel rabbet again. You will likely notice that when you dry fit the plank without twisting or forcing it into the rabbet at the foot of the stem, the curved area will tend to move upward a bit, which will give you some space between the edge of the template at the curve and the rabbet. At this point keep / secure this template in place where ever it falls and tape a thinner paper extension to it and redraw the curve to follow the rabbet at the curve. As mentioned above in step 3, you will also end up with a plank that is too short.
Step 5 you now have a new template, a combination of the 1st template and the extension, cut the curve in the new / modified template: the top edge of the template should be straight.
Step 6 dry fit the new template and adjust as needed so that the plank runs naturally: not forcing the curved area up or down to fit into the rabbet. When happy go to step 7.
Step 7 transfer template to lumber.
Step 8 cut the plank with curved area, leaving a little extra material (the portion of the plank fitted into the rabbet) for fine tuning before final installation into the rabbet.
G