It can be folded to 1/3 of its size and pop-up ready for action at a moment's notice. I liked the fact that it was absurdly lightweight (13 oz.) and did not require any permanent modification to your canoe...it can be simply secured to seats or thwarts with two unobstrusive clips
On the stern seat for scale>
The larger version of this sail (the "Cruiser") has been reviewed by canoeists before...check out this one over on Song of the Paddle. Since my boat is a very light, 14footer I went with the smaller, more manageable "Adventure" sail which seemed a better fight for my canoe. Like MagiKelly's review, I found the sheets to be awkward to hold at the location the sail was placed...so I ended up using an extra bit of line tied with a tautline hitch on one end which allowed for some lateral adjustment and attached this new line to the center yoke with a quick-release highwayman's hitch. This freed up my hands to steer with a paddle and in case I needed to bail out, a quick yank of the free end line and the sail would immediately collapse forward onto the deck and power down.
Rigged up with clips to the seat
You can also power down by pulling the lines in - after a very moment of acceleration, the wind spills over the top and the sail collapses under its own weight. It would then rest easily on the the widest portion of the canoe until you flicked it up again to catch any wind. In practice, this is where my tripping packs would be and the sail could easily lay on top of them without hindering any paddling performance. When portage time begins, it can then be recoiled and secured to the seat easily enough for transport across the trail.
Easily pulled forward
When needed again, a quick flip up and the sail begins to capture wind again...
All in all a lightweight bit of gear that I plan to bring along on some overnight trips next summer to take advantage of any blowing wind.