I agree with Jesse, get an inflatable PFD. Stearns / Sosuspenders / Mustang, etc.

http://www.landfallnavigation.com/inflatablepfds.html
http://www.nextag.com/inflatable-life-vest/stores-html

Her are a couple links to inflatables. I also use the manual release, it seems sometimes, not often, but sometimes I like to sit down in the stream 'to cool off', inother words I sort of fall down on my rear, and I would not want the vest to inflate when I am in shallow water. I also suggest buying at least one spare air cartridge, just in the event there is an accidental inflation, you can then release the air and screw in a new cartridge.

Just make sure the vest you get is a US Coast Guard approved vest. By the way, up in Canada, for an approved vest it must be a brand that has the Canadian Coast Guard approval on it or it does not qualify as a PFD in a vessel. Same vests as down in the US but they cost more for the Canadian approved ones.

Wear the vest, it weights nothing, you won't even know you have it on once you get used to it AND in the event that the canoe should tip over, like do canoes ever tip over? then you will have it on and ready for instant use. I can almost guarantee that if you have a standard type PFD vest you will not be wearing it since it is bulky and hot and when the canoe tips over, you will have nothing at all to protect you.

Buy the inflatable PFD's and wear them. The life you same may be your own, your loved one and maybe your best fishing buddy. If he won't wear the vest then ask him if you can have his fishing stuff when he fails to surface. Just joking.

Larry ---sagefisher---