Sheer line discrepancy


LOVES Wooden Canoes
We are building a form based on our circa 1927 St. Louis Meramec canoe and in taking measurements for the templates have noticed a minor discrepancy in the sheer line between bow and stern. Is this a typical finding? Due to the age of the canoe or would there have been that much variation when the canoe came off the form? (Perhaps completed on "casual Friday?") We also have a St. Louis Boat and Canoe guide model circa 1935 where the sheer line is the same at bow and stern. Not sure how to proceed with the measurements we have. Thanks.
Truth of the matter is wood is not always a predictable material. The descrepancy may have been built into the canoe (for example, while the decks were being installed, it is easy to shift the rails relative to the deck and affect symmetry). The canoe may have changed shape over time (due to simple wood movement or improper storage), and so on...

What folks taking lines from a canvas canoe that is symmetrically double-ended is to choose the quarter that looks most fair, and record the offsets from that quarter.

Then, you go to the lofting board and redraw the canoe. DO NOT SKIP THIS STEP! If you do not loft the boat prior to building, you run the risk of building and unfair canoe, and even reproducing all the flaws that exist in the old canoe.