I also take exception to the idea that paddles don't slip. It is physically impossible to propel the boat forward without pushing something backwards. Newton pointed out that for every action there is an equal and opposite reaction. In other words, Momentum is conserved. For the math enabled, momentum is mass times velocity. All that you can change is the mass of water you push and the velocity you push it. But you must make it move or "slip". A smaller blade will push less water so in order to impart the same momentum to the kayak, it must move the water faster. This is slip. It is unavoidable. The smaller the mass of the water you push, the faster you will have to push it to get the same speed in your kayak. The energy imparted to the water is equal to the mass of the water times the velocity of the water squared. Because the velocity term is squared, increasing the velocity of the water increases the energy imparted into the water much faster than increasing the mass moved. Any energy you impart to the water is energy you could have used to make the boat go faster. It is wasted. Everything else being equal, smaller paddle blades are less efficient than larger blades. There are ways to make a blade push more mass with less increase in velocity which depend on technique. For example angling the blade so water is shed of only one side and making sure the blade is fully submerged before adding power. One clue that a blade is less efficient is, when using the same basic technique, the less efficient blade will require a higher cadence to produce the same boat speed. However a faster cadence can be more efficient if it helps increase the mass of water pushed and the velocity that you push it. A longer stroke will give the water more time to accelerate and thus increasing the kinetic energy of the water (wasted). By using relatively short strokes the blade spends more time in water that is not moving (slipping) as much so more water is moved more slowly. Yesterday I was in a kayak shop where the salesman was saying that smaller blades are like a lower gear. This is not correct, they are like a slippery gear of a bike chain which jumps. I don't think this is an advantage. While smaller blades will feel easier, they are just less efficient. If you want a lower gear, you should keep the blade size the same and shorten the shaft. Because longer shafts also tend to produce longer strokes they can also make the paddling less efficient, by imparting more velocity to the water. This disadvantage can be overcome with technique. Unfortunately, most people accept the idea that smaller blades are like a lower gear and are also convinced by salesmen that they need a relatively long paddle for some reason. So, the end up with tiny blades stuck on the end of long shafts. That is just silly. It provides all the disadvantages, with none of the advantages of a well designed paddle. On a related subject. The drag your paddle experiences in the wind is proportional to the velocity of the wind squared. While it is true that we may spend 1/4 of our time paddling into the wind, that time is the hardest. If you are paddling at 5 mph in a 15 mph wind the apparent wind going up wind is 20 mph and down wind it is 10 mph. And since your paddle is actually going approximately twice the speed as your boat, the apparent wind on your paddle is 25 mph upwind, 5 mph down. In other words the wind drag on your paddle will be 25 times as much while going up wind as the saile force it gets going down wind and 2.78 times the force on the paddle from a the same side wind. Feathering paddles is not a crock. It makes a big difference and it makes the difference where it is most useful... when you are going upwind. I am sure many of you have noticed that a wind never seems as severe when you are paddling with it as when you paddle directly into it. There is a sound physical reason for that feeling and that is what a feathered paddle is built for. Nick >From: "Kevin Whilden" <kevin_at_yourplanetearth.org> > > >> Blade size does not matter, because as Matt Broze said earlier, water is a >> heavy fluid and even most small blades hardly slip through the water. > >It's too bad that John Winters isn't around these days, cause I'm >sure he'd have >some interesting comments on this. I've spoken to him a couple of times about >paddle design (last time exactly a year ago this coming weekend) and he's >pointed out that this notion that the blades "hardly slip" is a misconception. > >It's interesting that avid paddlers feel that the paddle blades >don't slip. I've watched >many canoe and kayak paddle strokes trying to understand exactly >what's going on. >They slip a lot! Paddle with part of the blade above water and >watch how far the >vortex travels from the blade while it's in the water (don't confuse >it with the persistence >of the vortex after the stroke is over). That's paddle motion. The >problem is that >you have a hard time separating the relative motions of the paddle compared to >the kayak, you compared to the water and the paddle compared to the water. > >All other things being equal, I'd not discount the significance of blade size. > >Mike -- 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. 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