At 6:23 PM +1200 9/17/02, Grant Glazer wrote: >Hi Nick, > >>From somebody who knows zilch about physics: >I think the difference is in the rate of strokes per minute. The >acceleration of a Euro comes from a broad blade pushing a large amount of >water. Since the narrow GP can't push the same amount of water, initial >acceleration is less. I'm not sure if this is caused by less blade area or >the high aspect blade shape of the GP since working out the m2 on curves are >not one of my strong points. Comparing my Euro's (19cm x 44cm) and GP's >(9cm x 92cm) I suspect the blade area is not much different so the shape of >the blade probably accounts for it. > >Once the boat is moving the GP paddler will have a higher rate of strokes >then a Euro paddler in obtaining the same speed. But the GP uses less force >with each stroke thus the over all energy used is less. The speed I'm >referring to depends on the paddlers "comfort zone" on how much effort they >use to obtain a particular speed. By increasing the rate of strokes in the >Euro you will of course always go faster then the GP since the Euro will be >constantly accelerating until the max hull speed is reached, but effort used >would still be higher and for cruising a balance between speed and effort is >found to suit the individual paddler. > >When I say that my GP is just as fast as a my Euro once up to speed, I am >referring to the effort needed in obtaining my comfortable cruising speed. >The GP strokes per minute is higher but the energy used is less. No >scientific prove here its just what I've noticed. The energy required is quite likely more, but it does it in a way that is more comfortable for you. Do not mistake force for energy. Less force does not mean less energy. If you apply a lower force you may end up using more energy even if it feels easier during each stroke. And think about it. A boat going at a given speed has a certain amount of drag. This is not effected by the paddle. The whole reason for paddling is to overcome this drag. If there was no drag, you could stop paddling once you were up to speed. So if you have two paddlers side by side going the same speed in the same boat paddling at the same cadence, the net force applied to maintain speed must be somehow equivalent regardless of the paddle. If it weren't then something must change, either the boats, the speed or the cadence. Lets assume it is the cadence. How does this happen? If the two paddles have the same "traction" on the water then it would just be a matter of changing how fast you put your blade in and out of the water and not really something related to the blade shape or configuration. I.e. it is a technique issue. If there is something about how the blade moves through the water that lets one move faster than the other then it is the paddle itself and not technique. As a paddle slips through the water during a stroke (which all paddles do) it applies energy to the water. Moving the paddle faster increases the energy applied to the water by approximately the square of the paddle velocity. The energy going into the water is energy that could have gone to into greater speed for your kayak. By making a paddle that is easier to pull through the water you make the apparent force less, but you do it by increasing the energy added to the water at the expense of energy added to the kayak. There is benefit to decreasing the force on the paddle, but there are consequences. The paddle becomes less efficient i.e. you get less forward energy for the amount of energy applied to the paddle. If a paddle feels easier to pull on, it is a sure sign that the paddle itself is less efficient. Imagine pushing off the bottom, while this is quite hard (high force), it is almost 100% efficient. Imagine just swinging your paddle through the air, while this doesn't take a lot of force and may be quite comfortable, it is very inefficient at making a kayak go forward. Please understand that I don't mean to say a less efficient paddle is "bad", just that there are consequences for making the paddle more comfortable and there are easy things you can do that will have predictable results if you seek other performance characteristics. The goal is to find some balance between what is most comfortable and what is most efficient. We have control over both. There are often easy things you can do that make a paddle more comfortable without sacrificing efficiency and there often are easy things you can do make a paddle more efficient without sacrificing comfort. Nick -- Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 (860) 659-8847 *************************************************************************** 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/ ***************************************************************************Received on Tue Sep 17 2002 - 06:56:32 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:30:59 PDT