What Solus says re: the different styles of paddle makes sense to me and rings true to me based upon my personal experience with both types of paddles. True, I've had the "illusion", at times, that I was going faster with the double-blade - and, perhaps, for a period of time, I was - but I always ended up returning to my trusted bent shaft. I did this for several different reasons. I wasn't used to the motion so my shoulders & chest would tire out. OR, the "metal" double-blade I own proved too heavy for anyone to sustain for very long. OR, I'd run into wind & water conditions that seemed out of my comfort zone using the double-blade, etc. & so on. Anyway, I've always bounced back to the bent shaft.
I have allowed that a lighter double-blade paddle of the right length, more training on technique, a different kind of canoe, etc., might help my double-blade paddling. However, the more conversations I have with folks who actually build & sell the canoes I paddle, the more I hear about the "physics" that Solus has described so well based upon design of the vessel, etc.. I appreciate the fact that Solus allows for the idiosyncratic styles of other paddlers who might actually perform better with double-blades. I DO know they are a dedicated bunch. You'd have to pry their double-blades out of their cold, dead fingers before they let go. I figure there must be a reason for that; it must work for them, to some extent.
Anyway, my only point is that my own personal experience and research match up well with what Solus outlines. I'd be quite willing to race a double-bladed paddler in the SAME canoe as mine over a distance of two or three miles using my bent shaft. In fact, I'd bet a case of beer on it. Please note, I'd be far less inclined to make that bet over a shorter distance... say, half-a-mile. Inefficiency might not take its toll over such a short length....
By the way, I think I recognize today's POD. Bill, I assume these are still shots taken from that 2006 expedition, right? Regardless, nice pic!
Jimbo