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stroke [2026/09/18 15:15] pstureavley |
stroke [2026/10/01 19:54] (current) pstureavley |
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| - | From [[https://guillemot-kayaks.com/how-paddle-works#:~:text=Ventilation is what you call,average kayaker creates is ventilation.|Guillemot Kayaks]]: | + | From [[https://guillemot-kayaks.com/how-paddle-works#:~:text=Ventilation is what you call,average kayaker creates is ventilation.|Guillemot Kayaks]] (with a couple of notes from our wiki editors): |
| - | <WRAP center round info 95%> \\ **Ventilation** is what you call it when the paddle sucks air down the back of the blade. Many people call it **cavitation**, but that is when a propellor spins (Ed. or any object moving fast enough in water) so fast that it creates a vacuum behind the blade (Ed. Note: imperfections in a blade also contribute to cavitation, but this is not really vacuum formation, but rather the formation of low pressure space behind the moving object or blade that causes water vaporization). Neither is any good, but **what your average kayaker creates is ventilation**. The reason it is no good is you are moving air instead of water. Air weighs a lot less than water and if there is air behind your paddle instead of water the mass of water you are moving is decreased and thus creating the same momentum requires you expend more energy. | + | <WRAP center round info 95%> \\ "**Ventilation** is what you call it when the paddle sucks air down the back of the blade. Many people call it **cavitation**, but that is when a propellor spins (Ed. or any object moving fast enough in water) so fast that it creates a vacuum behind the blade (Ed. Note: this is not really vacuum formation, but rather the formation of low pressure space behind the moving object or blade that causes water vaporization). Neither ventilation nor cavitation would help your paddling, but **what your average kayaker creates is ventilation**. The reason it is no good is you are moving air instead of water. Air weighs a lot less than water and if there is air behind your paddle instead of water the mass of water you are moving is decreased and thus creating the same momentum requires you expend more energy. |
| - | There are **two ways of creating ventilation**. One is by bringing the** air down with the blade as you insert it into the water**. The other is to pull **air down the back of the paddle as you apply power**. Both can be avoided by being sure your blade is fully submerged before applying power (Ed. We believe that everyone starts to apply some power before their blades are completely submerged, but the idea is to have your paddle mostly submerged by the time you start to apply the peak of your power). **A clean entry will not bring down much air** and the small area near the top of the blade is less likely to ventilate. \\ </WRAP> | + | There are **two ways of creating ventilation**. One is by bringing the** air down with the blade as you insert it into the water**. The other is to pull **air down the back of the paddle as you apply power**. Both can be avoided by being sure your blade is fully submerged before applying power (Ed. We believe that everyone starts to apply some power before their blades are completely submerged, but the idea is to have your paddle mostly submerged by the time you start to apply the peak of your power). **A clean entry will not bring down much air** and the small area near the top of the blade is less likely to ventilate." \\ </WRAP> |
| - | **More on Cavitation **- typically occurs with objects that have some kind of edge (does not occur with spheres). Previously cavitation was thought to only be caused by high speed movement, but it has subsequently been experimentally observed with objects moving as slow as 1 meter per second. So theoretically it may be possible for a paddle blade to cause cavitation, but **we currently believe that ventilation is the primary issue that paddlers are dealing with and should try to minimize**. | + | **More on Cavitation **- imperfections in a blade also contribute to cavitation which typically occurs with objects that have some kind of edge (does not occur with spheres). Previously cavitation was thought to only be caused by high speed movement, but it has subsequently been experimentally observed with objects moving as slow as 1 meter per second. So theoretically it may be possible for a paddle blade to cause cavitation, but **we currently believe that ventilation is the primary issue that paddlers are dealing with and should try to minimize**. |
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