Read the thread again. Rollin made the point succinctly and well: you can't steal someone else's design. People may do it, but it's almost always wrong (legally and ethically).
Almost. As to modern canoes Rollin is absolutely correct, no exceptions. However, many of the classic designs by late 19th - early 20th century builders have now passed into the public domain and may be copied without permission. For example, designs by Rushton, English, Peterborough, Morris and E. M. White have very probably lost all legal protection. That is why you can puchase reproductions (and very fine ones at that) of a Rushton Indian Girl, Morris 17 or E. M. White's Guide by modern craftsmen such as Rollin Thurlow and Gerry Stelmok. I haven't researched the issue closely, but I'd be surprised if the design for the Old Town 18' Guide (developed at about the same time as E. M. White's Guide) weren't also in the public domain. The same may also be true for the ubiquitous Peterborough/Chestnut Prospector. So, maybe you can legally copy them - maybe. But even if you could, is it ethical? As for defunct companies (Rushton, English and the like), where there is no risk of economic harm to the long-gone designer, it would be hard to make a case that copying is unethical. For the few original companies that remain in business today - most notably Old Town - I think it's much more complicated. Just don't expect Old Town to help you in the process.
For myself, I try to support a company like Old Town by buying its products where I can. Regardless what you might think about Old Town's commercialism today, the fact that a huge conglomorate is still crafting wooden canoes is a minor miracle. So I say don't cop the design for an 18' Guide, buy the canoe from Old Town. Just skip the fiberglass.
And, sorry for the "chummy chat."