I see you guys are starting to understand the problem I uncovered when I discovered the test plank did not follow the lines of the ship...
I may have some insight on this issue. When I started trying to lay the first hull plank along the entire length of the hull framework, it became apparent that the height of the plank location, somewhere between the turn of the keel and the upper side, was a HUGE factor in how that plank lay on the hull. It may curve upward at sharply at both ends if the plank is too low, or lay straight across if too high. Somewhere in the middle of those positions, the front end may curve too sharply upward as it ran to the keel at the bow and only gently curve up at the keel end. You're trying to locate the position where the first plank will be laid, and you know it will influence the shape of all the planks that are laid beside it for several strakes up and down. Knowing where to start planking comes from experience, and the style of building that is uniquely yours.
For the first plank layer, I like to start at the lower gun deck, with the first plank just below the lower gun deck ports. On the final plank layer, start below the wales. It is at a position where the flatter area of the sides of the ship start to curve into the lower belly of the hull. Another starting place where you place a second full length plank is at the keel, and your work toward the turn of the bilge (the red line where the lower side of the hull curves sharply into the bottom). The tapering, drop planks, and stealers required for planks between these two starter planks work themselves out as you go. At the bow, you judge the width at the keel remaining to be filled, and add drop planks carefully as you work, adding planks from the bottom upwards. To fill in the bottom of the hull, you start at the keel with the garboard strake, move outboard toward the turn of the bilge, and use tapering to squeeze the ends in, or stealers at the stern to bridge the widened gap. Below are pictures showing progression of the first plank layer.
The hardest part is judging how many drop planks you need from the turn of the bilge up to the beakhead deck at the bow end of the ship. Now, I tend to work freestyle. That means that I do not use the measuring method at each frame and calculate precisely how much taper goes here or precisely when planks are approaching their half-width threshold and require a drop plank be fashioned. I work by eye, and for me the results are always symmetrical port to starboard, because I'm very careful. Many people cannot do that because they don't have a mind that sees shapes in three dimensions, in the way that I can cover a man in steel plate armor by eye, whacking out steel into 3-D on the anvil so that an armor suit's parts fit with minimal trimming and no gaps. That's my profession. If you asked me to paint a portrait, you'd get a stickman, and not very good one. The point is that your method will vary, depending on your personal experience, skill, and innate talents.
Only two drop planks were required on this hull, one next to lowest wale, the other more visible three strakes down from the wale. Note that they were done in the English style when they should have been Dutch.
