suggestion by Doug for a PLB is a super good idea.
I have done plenty of canoe trips in my time.
ALWAYS a blast.
But the main thing about canoe trips - it is always a PEOPLE problem. it's never an equipment problem. You can always get a pretty good amount of equipment and food in a canoe.
It always boils down to HOW PEOPLE COOPERATE.
If you ever want to see a knock-down drag-out fight ... put two stangers in one canoe. It takes close cooperation to go anywhere. Most people FALL APART fast on that "cooperation thing".
I highly commend you for trying this with your troop. Seriously. I suggest that as the Team Leader - you be prepared for major failures in teamwork and cooperation. It is guaranteed to happen. Be prepared to SWITCH partners, and do a lot of conflict resolution.
REMEMBER ONE THING.
Your Troop is watching how you respond to each "crisis". If you can avoid coming unglued - chances are that you will have a great trip. And take some kids Tylenol - you'll need it!!
cheers,
Pete