One of the issues with any type of cutting edge technology product, such as graphite/carbon paddles is that the margins of error in the manufacturing process are often not well understood or defined. And I've never even heard of an engineering design guide standard for paddles.
In the quest for weight savings, we need to be cognizant of what we are potentially giving up. It's like light beer - it can't be less filling and still taste great. When you buy a very lightweight paddle you should understand that you are giving up some of the strength that would be in a heavier paddle of the same material. Over the years I have seen numerous graphite/carbon paddles break - always in the shaft away from the ferrule. As Woody noted, all of the breaks I have seen have been catastrophic - no warning signs. I have also seen several wooden paddles of euro and greenland design break. Wood is a material with inherent inconsistancies in its structure (such as knots and grain) and a well made wood paddle minimizes these inconsistances, but again, just like a graphite paddle, the closer you push the limits on weight the less margin of safety you have for possible breakage. I have yet to see a glass paddle break in the shaft. I have seen one very light glass paddle break in the blade when the extended grip was used and the paddler didn't know how to properly brace. Perhaps backup paddles should be glass.
Last year I experimented with building a number of foam and graphite paddles. I could come up with very very lightweight paddles, but I pushed the margin too close on them, and they all (except one so far) have ended up failing - almost always catastrophically. In the case of one paddle, I was surfing along on a wave, dug down with a stroke, and suddenly realized the lower half of the paddle was missing. Surfing the remainder of the wave with the short half of a paddle was invigorating! But, as always, I was carrying a spare paddle and was able to finish the trip using the spare.
I have one wood paddle that I made out of an extremely light piece of cedar. The paddle is a joy to use, but the lower the density of red cedar the lower the breaking strength. I would not trust that paddle in surf or rough conditions. It only comes out for calm protected paddles, and as always, I carry a spare paddle.
How close you cut that margin of safety is a personal decision, but you need to be cognizant of the consequences, which, in this case, could include the breakage of a paddle at a very awkward or dangerous moment.
I have mentioned the idea of carrying a spare several times, and it has been referred to in some of the posts in this thread. My personal rule is to always carry a spare on any kind of trip. But simply carrying the spare paddle is not enough. You need to be able to get the spare out of the stored location on your boat while you are on the water, in your cockpit, and by yourself. I look at many of the spare paddle storage setups on manufactured boats and can not figure out how I would get the spare out while on the water without someone paddling up to me and doing it for me. Some of these storage positions are too far toward the stern of the kayak to be reached from the cockpit. Many storage systems are rigged for the paddle blade to be the end of the spare paddle nearest the kayaker. I have tried to use spare paddles from positions where the blade is closest to the cockpit, and have either been unable to get the paddle, or had difficulty. This is especially true when the euro paddle is stored so that the tip of the blade is curving down to the deck and not up away from the deck - there is nothing to grab to get the blade, especially if you are wearing gloves for cold water.
My strong preference is to carry the spare take apart paddle with the shaft ends toward the cockpit. I have practiced getting my spare paddle out from this position and can do it easily from on the water, and from an upside down position to roll up with half a paddle. I suspect that for most people the best place to store a spare paddle is on the deck IN FRONT of the cockpit with the shaft ends facing the cockpit. This would eliminate having to turn around to get the paddles - often an area where you can not see what you are doing and are relying on feel. However, most of us, myself included, carry a bunch of other stuff on our front decks, precluding keeping the paddle here unless it's a greenland paddle.
See my blog at
http://mysite.verizon.net/gdwelker/ to see photos of boats with different deck riggings for storing paddles.
At this point I get to put in a plug for carrying a greenland type paddle. The greenland type storm paddle is shorter than the standard greenland paddle, and will fit on most kayak stern decks without significant overhang of the stern. Carrying a storm paddle as your backup allows you to grab a paddle that is already assembled and ready to paddle with when you need it. Can you assemble your take apart paddle while bouncing around in bad conditions? Can you roll up using only half of your take apart paddle? If you know how to roll, you can roll up with a storm paddle almost as easily as with a full greenland paddle, and we know rolling with the greenland is easier than the euro.
End of greenland plug.
Spare paddle don't need to be the same model you normally paddle with, and can definitly be less expensive models. My first spare paddle was a sevlar screw apart kayak/raft paddle - but at least I had a spare! My second one had a metal shaft and plastic blades - but I had a spare!
Oh yeah, and when was the last time you put together that spare paddle and actually paddled with it?[url][/url]