I am late to your discussion so bare with me.
First, a couple questions.
1) You post the question in the "Stripper" section, but the discussion touches on everything from W/C to tupperware boats. What exactly are you thinking about building? Of are you just looking for info to buy a boat?
2) How do you plan to use this canoe? Is this for BW/Q work or shallow rivers or casual lake travel or somethiong else?
Now for weight:
My interest in canoeing is in the lake travel of the BW/Q, sometimes we've paddled rivers, but that's not my thing, so with that disclaimer:
Back when I was younger, I paddlied and portaged std weight grumman alum all over the area, I believe it was in the 72-74 lb range but don't know for sure. It was heavier then the std 17' Alumicraft me also paddlied. (The Alumicraft were also faster.) I was a dry footer, ie, I would drag that canoe over anything to avoid getting my feet wet.
As I got older, it got heavier, and now it's too heavy for me, so I went down the path of building a/several strippers to get a better/lighter canoe. (Plus I just wanted to build one.)
Anyway, the 1st is/was 17.5 ft, a modern tripper design. I used the std 6oz glass/1/4 wood/6 oz glass layup plus a second layer of glass in and out in the football. This canoe got way too much resin and ended up at 72 lbs, it seems to be fairly string and is stiff but is way too heavy.
Between the 1 and 2ed stripper, I did some research and learned a bit about glass and layups. There are sites that discuss this out there but in short, for a stronger layup,
1) more glass weight then wood,
2) glass to resin ratio at 50% or better,
3) thinner glass fibers are stronger per weight than thicker glass fibers,
4) 2 layers of thinner glass are stronger than 1 layer thicker glass, ie, 2 3oz are stronger then 1 6oz.
It's easy to make a light canoe, it's very hard to make a light tough canoe.
The 2ed canoe was 2+2 layers of 2.3 oz glass, over 3/16 wood. And it got stretched to 18.5 ft. This time the hull was 40 lbs, but the trim was heavy at 18 lbs, making a total weight of 58 lbs, not too bad but still not light enough.
The 3rd canoe is not finished, as it still needs to be trimed out but, after learning more about glass and glass strength, I learned that the 2ed canoe wasn't as strong as I wanted. So a different layup, this time 2 layers of 2.8 oz with 2 layer of the 2.3 layed at 90 degrees both in and out. The strips are 3/16 in the bottom, thinning to 1/8 on the sides. This layup is significantly stronger then either the std 6 oz or my 2ed layup. this canoe is a different, more full design, meaning more surface area, it's still 18.5 ft and in varnish weighs 44 lbs. It will probably have 10-12 lbs of trim pushing the total finished weight to 54-56 lbs. Not bad for a large (hopefully) tough tripper, but a lot of work.
If all you want is a light canoe, buy a Souris River Q 17. They are light and are building a rep as being tough.
If you are looking for a river boat, get a plastic one.