Solving Buoyancy & Swimming Problems: Advice for Tangler

[Tangler]

I have a question which relates to buoyancy and swimming.
One of the basic skills required to be a good swimmer is to be able to maintain a horizontal postion throughout the length of your body whilst swimming front crawl but to rotate your whole body about a horizontal axis which passes through the top of your head.
In order to develop this skill coaches recommend the following two drills (i.e. skill practice methods)
1. Front balance - float face down with arms at side and kick very gently with feet.
2. Side balance - rotate from front balance position onto your side with head looking down to pool bottom.

My query relates to the buoyant forces which act on the body during this rotation.

I have mastered the front balance drill. But i have a problem with the side balance drill in that my legs angle down into the water but pop back up when I return to a front balance postion.

The body can be split up into two distinct zones.
1. the lungs/chest - a box shaped area which is very buoyant.
2. the legs - cylindrical appendages which are very heavy (my legs are lean i.e. not much fat)

The centre of gravity lies between these two areas approximately in stomach area.

It seems that when i rotate to a side balance position there is an imbalance in the forces which causes my legs to drop.

Does the centre of gravity shift or is the buoyant force of the chest greater when on my side?

Any help would be greatly apreciated.

Thanks in anticipation

Tangler

 

[Valerie Park]

The buoyant force of the chest is likely to be greater when on your side. This is because when you rotate onto your side, more of your body is submerged in the water which increases the area of your body that is exposed to the buoyant force. This increase in the area of your body that is exposed to the buoyant force will create an imbalance in the forces which causes your legs to drop. The centre of gravity does not shift during this rotation; however, the imbalance in the forces causes a shift in the position of the centre of gravity.