I won't repeat or comment directly on the many comments on paddles already posted and will just pass along some information gleaned from tank and real life controlled testing (done by myself and others) as well as various hydrodynamics texts. This is not a full discussion of the topic only a brief and outline of basics. Paddle thrust (thrust = the effective power transmitted to the boat) is a function of drag and lift. Drag is a function of area, drag coefficient ( drag coefficient is a function of the paddle shape both profile and section) and velocity. Thus a smaller, lower drag paddle can produce the same thrust as a larger higher drag paddle if one moves it through the water (greater slippage) at a higher velocity . Slippage is an unfortunate word as it seems to have negative connotations but neither drag nor lift can be produced without it. So greater slippage may not mean a loss of effciiency nor does it always mean an increase in efficiency. It just means the paddle is moving through the water. Lift also depends upon area, shape (profile and section) and velocity as well as angle of attack through the water. Thus a small blade at a higher velocity might produce as much lift as a large blade at lower velocity. The paddle velocity desired by a paddler seems to be a function of biomechanics. I.E. a small person using smaller fast twitch muscles might produce greater efficiency (better use of their strength) using a higher cadence and, therefor, a smaller blade. A larger person making greater use of slow twitch muscles might refer a slower cadence and large blade. A good exxample of this is the different sizes of blades used by racing paddlers. Kayakers using less body trunk strength and more lift genrerated power paddle at a higher cadence with smaller blades than canoeists who use a great deal of body trunk power and more drag generated power. The length of the paddle depends primarily on the style of paddling preferred as well as auxillary uses (such as rolling etc.) For example if one prefers an upright style of stroke with more lift then a shorter paddle seems to produce the best results particularly if the cadence is higher. On the other hand those who use primarily arm strength and a stroke developing primarily drag might prefer a longer paddle. Regardless of stroke style it always seems best to minimise paddle weight. To achieve this with a paddle used primarily to produce drag force one would seek out a high drag paddle I.E. one that produces the greatest drag per unit area. Tank tests I and others have performed have shown that low aspect ratio paddles have the greatest drag coefficients so a low aspect ratio paddle can be smaller and have less weight. Oddly enough the "high" lift paddles also have greater efficiency at lower aspect ratios (contrary to traditionalist belief). Tank and wind tunnel tests as well as controlled paddling tests have suggested why. Paddlers use their paddles at very high angles of attack much like a sailboat on a reach where lower aspect ratios produce more thrust per unit area. The high aspect ratio rigs on modern racing sailboats are designed around racing that focusses on beating to windward at low angles of attack. When sailing off the wind they modify their rigs to lower aspect ratios using spinnakers. The common admonition to "choose a paddle that feels best" works if your concern is primarily how it feels. On the other hand, if you want to achieve higher efficiency you may want to choose the most efficient paddle and adjust your style etc. to suit. The choice is yours. Because people vary so much in paddling intents and physical development it seems difficult to come up with any "right" paddle. In fact, it may be that ones aesthetic prefernces outweigh everything else. Many people just want a pretty paddle and will swear thiers is more effcient just because they like its looks. Real life testing does an excellent job of confirming a persons likes or dislikes. Unfortunately it doesn't work so well when you want objective results. Cheers, John Winters *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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