I have the Nahanni from Langford mentioned in a previous post. I took it out with my two granddaughters when they were 6 and 8 and again when 7 and 9. It felt smaller already on the second trip. We had it packed tight. I would recommend a 17 footer, but not a prospector, the high and wide bow is too hard to control solo. The newer asymetrical designs are better for soloing.
No need for sliding seats. We take two trips on portages because I cannot carry both the canoe and a big pack, but that means they each have two small packs. Lots of packs to put in lots of places to achieve balance.
The boat came with a kneeling thwart just back of the centre yoke. I kneel, they sit on the seats. That way I can control the boat easily as if I was solo. By sitting at the stern the older girl has learned all the steering strokes. Sometimes I am now just a passenger!
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shearjoy Sometimes your joy is the source of your smile, but sometimes your smile can be the source of your joy. Thich Nhat Hanh