Embarrassed? I don't see why I would be embarrassed ... maybe because, sorry, but I still don't take your preferred wording as a "correction"; rather, I still see it as an alternative. I understand your logic, but I can't just dismiss the way the song has been sung for 150 years or so in Newfoundland, and the words chosen by the author/compiler of the Newfoundland lyrics, as "wrong". If someone shows me that the phrase I'm familiar with came about by way of an error on the part of the author or an early printer, and was just blindly repeated by generations of Newfoundlanders, then I might be willing to concede that it is in a sense "wrong" - even if well-established by tradition.   But I'm still not entirely convinced that in the vernacular of Newfoundland seamen of 150 years ago "reef the main boom" didn't have a distinct meaning. For example, I don't know why it couldn't have meant "reef the sail that is fastened to the main boom". You would know better than I if that would be much of an accomplishment on a vessel large enough to be called a "trader" ...

(And yes, I'll probably sign up one of these days ... !)