I have not seen or used the Accent paddle.
Cupped or curved power faces are becoming pretty common on recreational whitewater canoe paddles. Some examples are the Aqua Bound Edge and the Werner Bandit, and at the higher end the ZRE Power Curve and the Mitchell Premier (although the premier can also be ordered with a flat blade). I own and have used a Bandit, AQ Edge, and a ZRE Power Curve and have borrowed a Mitchell Premier curved blade briefly.
Werner actually refers the the Bandit as a "spoon blade" paddle, but it would seem that a spoon blade would have concavity of the power face along both the longitudial and transverse axis. The Bandit and Power Curve have at least a little offset to the blade and perhaps minimal dihedral. None of them have what I would consider to be a spooned blade though.
Asymmetry is not a handicap since palm rolls are not (typically) done in whitewater. I do feel that the curved blade does allow a little cleaner entry at the plant and a subtly more solid catch than a straight blade does. I tend to notice the difference more on off side strokes. Other than the plant and catch I have not appreciated any other difference between these paddles and a flat blade.
Touring Kayak Paddles
Hardshell Kayak Sail Rigs
Pull-Up Strap Handle Kit
|Table of Contents|