I would think it's where each swimmer is the widest
probably in the hips, shoulders, or abdomen
Hmmm, what I meant is, when your body is completely underwater, or when the upper part is outside the water?
I seem to have read different opinions but can't remember where. Some say the greatest resistance is on the water surface. However, if the air has less resistance, shouldn't half air and half water be less resistant than completely underwater? :confused:
I've described the reason for deeper dives & push offs with:
Tip 239 The Suit Surge
from
Swim Faster Faster
Since the new permeable suits don't float was much as the rubber full body suits, I recommend taking in a big breath just before your turn and holding it while you streamline glide & SDK
Pushing off the walls and after the dive, we've known pretty much forever that you have to go little deeper than the surface in order to get more velocity. Phelps (among others) has pushed this principle to a new extent by literally diving deeper after each push off.
In addition to the "wave" action noted above, another scientific reason for increased resistance at the surface boundary is the energy you expel in breaking the surface tension of the water at the surface boundary.
during swimming? Completely underwater, or half underwater (water surface)? Ask breaststroke specialists. They are the one having to constantly face this dilemma.
I'm far from being a breaststroke specialist, but as a well informed observer, I think that the depth prescription for breaststrokers have changed over years. Not sure where it stands right now (and I don't really care).
Pushing off the walls and after the dive, we've known pretty much forever that you have to go little deeper than the surface in order to get more velocity. Phelps (among others) has pushed this principle to a new extent by literally diving deeper after each push off.
I'm pretty sure the greatest resistance is on the surface. Just from an energy balance, if you're right on the surface and you're making waves, it takes energy to do that. There is energy in the wake.
If you're far enough under water where you don't interact with the free surface, all of your energy can go into forward motion. If you're not Michael Phelps and you don't have enough lung capacity to go four feet down for 15 meters every turn (wow!) dolphin kicking on your side is more efficient because you won't interact with the surface as much. Illegal in backstroke, you can't be past 90 degrees, so you'll need to go deep to get the most out of the kick.
I've been working on SDK, though I still don't go deep enough. When I do hit the turn right, I can tell the difference and it feels faster, but it takes more lung capacity than I have to do it every turn, all the time.
While hydrodynamics are very complicated a good rule of thumb is that form drag(pushing and pulling water by our body's shape) goes up as the square of velocity,where as wave drag goes up as the cube(these are not nearly exact but close enough at elite swimming velocities.)In all strokes you want your head in neutral position as much as possible as raising your head causes some other part to drop(usually hips.)Head up breaststroke is definitely slower,if you can avoid raising your head at all you will be faster(breath by raising your torso at the point where the insweep naturally causes it to rise.)
More resistance on the surface. That's why submarines go faster when submerged. Also consider that some people can kick significantly faster underwater than they can swim on the surface.
Here's an experiment to prove it. Push off from the wall and streamline and see how far you go 1. while on the surface, and 2, while under water.
