John,
You can probably paddle anything with a double paddle but if the canoe is over 32" wide the paddle will have to be very long for a paddler that is in the widest part of the boat.
I paddle a Cheap Canoe which is only about 29" wide and use paddles that are 8'and 9'long. They both have beaver tail ends which makes them fairly heavy. I tried to use a lighter 7 1/2' kayak paddle but it had to be held at such a steep angle that the drip rings were useless and water dribbled into my lap all day long.
The only way to know what will work for any particular paddler/boat combination is to paddle the boat with whatever paddle comes to hand and use that as a baseline for what you build.
Charlie

: This isn't kayak related, but my brother paddles a canoe and I was thinking
: of making him a double bladed paddle as the first step toward converting
: him. Does anyone have dimensions and/or a link to dimensions for a double
: bladed paddle that could be used for a canoe? I assume that it would have
: to be longer since the paddler is higher up and the higher sides of the
: canoe will require the paddle to extend further out. Thanks.

: John