azalea wrote on Jul 20^th, 2010 at 11:28am:

Quote: One spare for 2 canoes?  That sounds like saying, "I have seat belts in my other car, so I'm covered." No it is not.  If you are in the second car and it crashes, the seat belts in the first car do you no good.  If   you lose a paddle in the second canoe, the paddle in the first canoe is as useful as having the spare paddle in the second canoe. A paddle is similar to many other "vital" items we take on trips: orienting devices, stoves, flashlights, paddles, canoes, tents.  We assess the liklihood and severity of failure, the weight, etc; and make a decision of how many (if any) backups to bring.

Gear you're actually using at the time isn't the same as gear you're not using at the time.  Having a tent handy isn't going to prevent you from going over a waterfall or from being swamped in big water.  

What good is a paddle in a canoe you're not in when you've lost the one you were using?  Not having a spare paddle handy when you need it is at best a hassle and at worst life-threatening.  Again, back to those situations when things are happening fast and a spare paddle 20 yards away may as well be in China for all the good it will do.

Cornerstone said it well.  It's a calculated risk.  I think those calcualtions show a fundamental lack of arithmetic skills, but it's not my Darwin Award.