OK this sounds like a stupid question but someone at the pool told me that my hand needs to be open with my fingers apart when I swim. i normally cup it which is what I thought was the best way. Today I tried my fingers together and my thumb out a little bit from the hand.
The cupped hand seemed best but what do the experts say?
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Former Member
The force you can generate with your hand will be dominated by form drag, basically the larger the cross-sectional area the more force you can generate. Cupping your hand to any extent will reduce the cross section and reduce the force. Holding your fingers together or apart doesn't change the area, just the shape. Having your fingers apart will increase the surface area of your hand increasing the surface drag, but the contribution of surface drag relative to form drag is probably not very significant. Learning to effectively use the entire forearm will increase the cross-sectional area a lot more significantly, using a high elbow position is the most important part of this. I don't actually like the term high elbow position because it refers to where your elbow should be if you are swimming flat, if you are on your side you want a wide elbow, the goal is a bent elbow so that your forearm is perpendicular to your direction of travel.
At least that's the theory as I understand it.
Actually, the mention of moving water brings up a topic I often wonder about: how much of the force is generated due to action/reaction/conservation-of-momentum and how much is due to viscosity effects? Swimming books often talk as though you can only accelerate forward by accelerating water backward when this clearly isn't the case, the viscosity of the water allows you to generate forces beyond simple mass momentum equations, but I don't know quantitatively what the relative contributions are. Anybody out there that is still up on their fluid dynamics?
The force you can generate with your hand will be dominated by form drag, basically the larger the cross-sectional area the more force you can generate. Cupping your hand to any extent will reduce the cross section and reduce the force. Holding your fingers together or apart doesn't change the area, just the shape. Having your fingers apart will increase the surface area of your hand increasing the surface drag, but the contribution of surface drag relative to form drag is probably not very significant. Learning to effectively use the entire forearm will increase the cross-sectional area a lot more significantly, using a high elbow position is the most important part of this. I don't actually like the term high elbow position because it refers to where your elbow should be if you are swimming flat, if you are on your side you want a wide elbow, the goal is a bent elbow so that your forearm is perpendicular to your direction of travel.
At least that's the theory as I understand it.
Actually, the mention of moving water brings up a topic I often wonder about: how much of the force is generated due to action/reaction/conservation-of-momentum and how much is due to viscosity effects? Swimming books often talk as though you can only accelerate forward by accelerating water backward when this clearly isn't the case, the viscosity of the water allows you to generate forces beyond simple mass momentum equations, but I don't know quantitatively what the relative contributions are. Anybody out there that is still up on their fluid dynamics?
