Not sure about the Hessel boat show. But if you're traveling through Marquette to get there (seems you would, or could, coming from Boundary Waters) the Marquette County Historical Society has a nice special exhibit on the history of the canoe. http://www.marquettecohistory.org

There's 10 or so boats on display (all but one being wooden) including a pretty cool sailing canoe and a "girling" canoe from the 20's.. Set up special specifically to court the ladies. My my how times have changed. The exhibit was funded by The Wooden Canoe Heritage Association. The museum is brand new and totally worth the stop and the $7.00 admission even if they didn't have the canoe exhibit.

The Munising area and Pictured Rocks would also be well worth checking out for future trips if you've never been.
I grew up in Munising, went to college in Marquette. Most of my/wife's family still lives up there.

Jealous of your Boundary Waters trip. We used to go every summer but haven't in the past 2. Actually, this year makes 3.

P.S. I didn't see the "please no photo's" signs until after I took a bunch of pictures...