I’m wondering whether there’s a relationship (inverse) between blade thickness and efficiency. I believe some claim a thinner blade improves efficiency because it offers less resistance when inserted into the water. I think there may be something to this but not sure. Any opinions?
Blade edge
From my experience with experimentation in shaping traditional paddles, I have found that a minimally sharp and clean edge on a paddle provides a clean efficient quiet entry. An added thickness to the blade away from the edge adds welcomed buoyancy in a traditional paddle for sculling and rolling.
Just my 2 cents (plus tax)
Depends (my favorite answer!)
What type(s) of paddle(s) are you talking about?
Thickness where? Edge thickness and/or overall thickness (and relation between and distribution of both)?
What definition of efficiency? Quick clean catch? Clean release? Max bite? Ratio of drag to lift? Buoyancy? Sculling and other control aspects?
Have you noticed the trend…
…in Euro paddles toward blades with thin edges that taper smoothly to thick, buoyant, center sections? These blades are not only more efficient, but they’re less angle critical when sculling or sweeping the paddle. Of course, the Inuit and Aleut peoples have known this for centuries. The Aleut also developed the dihedral blade centuries ago.
Werner Cyprus and Ikelos
Both are like you describe Brian…as they are foam filled for added bouyancy I believe. I actually have the Cyprus in 210cm though I haven’t used it much…(borderline heresy)
Greyak - you da’ man when it comes to technical paddling jargon!! All I know is that it has a wide edge for going faster and a thin edge for entry/exit/sculling/bow & stern rudders////
On my GP - I tend to gravitate towards sharper edges without being painfully so…which is why Don B had to put a walnut edge on my last GP…
Scott
blade thickness
Greyak -
I was referring to Euro paddles (should have said that). Also to the edge, not thickness away from the edge. And to efficiency of blade entry into the water.
Seems that thin edges impart greater efficiency as defined above, and that makes sense. I just wonder how much greater.
Nigel Foster’s paddle is like that, too.
The venerable Toksook is more or less in the same vein, if not in the same weight class. 
opinions
the most significant efficiency difference is how the motor is lining up the bones to transmit power.
After that pick anything. I don’t think there’s a practical advantage to knife edges compared to making the entire blade smooth like foam cored blades over blades with bumpy backs where the shaft is exposed.
I have a carbon Lightning with dangerously knife edges, the epic I got feels better. Whether that’s more efficient I don’t know.
No difference
If you had two versions of the same paddle different only in the thickness of the blade, could you detect that difference with your eyes closed? I doubt it. Since essentially no force is required to insert either paddle at the catch, there would be no difference at that catch. When applying power, the behavior of the turbulent flow around the sharp or thicker edges might be somewhat different, and this might change the drag coefficient slightly, but whether it would increase or decrease is unknown to me.
Hmmmm
my GP has a thick edge and is pretty robust in the mid section (Don Beale paddle) but my friendas comment on how quiet it is compared to euro paddles??
Add some 1/4" peel and stick foam…
…sheet (closed cell) on the back of your paddle blades, trim out, and see if you still feel this way after trying it
Thick edges = bad.
Simple simgle thickness blades on a stick = variable dependent on other features
Airfoil shapes (thinner edges some volume mid blade, with smooth transitions) = good
Airfoil?
The suggested experiment of taping foam on a paddle does not seem germaine. My old Descente had a thick blade, while my more modern AT and Werners have thin edges. I don’t believe there is any negative effect of the blade thickness. These are not wing paddles and are therefore drag devices, not lifting devices. Airfoil shape is not relevant.
If you’re going to limit…
– Last Updated: Oct-11-06 10:52 PM EST –
... the discussion to thin formed bladed euro paddles that are constructed much like a road sign -then OK. Difference between 1/8" or 3/16" won't matter. It's all about spoon or flat or dihedral, symmetrical or asymmetrical, low angle or high. Thickness with these is about materials and strength. Same for many wings.
If you also look at foam core euros, foam core wings, Greenland paddles, canoe paddles, etc., etc.... where thickness varies across the blade - and more than the power face shape is worked out - often more like an airfoil - then maybe there's something to talk about.
It’s all about flow…
…specifically water flow across the blade surfaces. Airfoil shaped cross sections are more efficient in that regard than the “road sign” designs. I love than analogy, BTW.