DNOWS Header

Image Map

Monday, March 26, 2018

Are You A Floater Or A Sinker In The Open Water?

Courtesy of Nuala Moore, Dingle, Ireland.

Nuala Moore, an open water swimmer and a veteran scuba instructor, is currently in Patagonia in the Southern Hemisphere. She is planning on swimming in Cape Horn, across the Beagle Channel and the Strait of Magellan this week, dramatically distant and different than her home base in Dingle, Ireland.

She discussed about buoyancy in the open water with us and explained why some swimmers are better floaters compared with other swimmers who have a greater tendency to sink.

"Archimedes stated in his treatise On Floating Bodies, 'Any object wholly or partly immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.' Despite the sweeping statement, it also holds that variations in buoyancy are dependent on the variables of the object (i.e., the swimmer) and the density of the fluid (i.e., the sea). The more dense the fluid, the more buoyant a force will be applied.

Salt water and fresh water differ on many levels, but the main difference is the weight of the water.

Fresh water is described as weighing 62.4 pounds per cubic foot. Due to the dissolved salts within seawater, salt water is more dense than fresh water.

Depending on its salt content (which is also variable), seawater weighs 64 pounds per cubic foot. The more weight or density the fluid has, the more buoyant a force it is able to exert upon objects, forcing it upwards
.

From a swimming point of view, the easiest way of looking at the water between fresh and sea water is the texture. Fresh water in rivers and lakes is light to the touch and easy to move. Sometimes, swimmers might experience the feeling that they are pulling air. There is no denying that the sea water is thicker and heavier to pull and drive the body through. Swimmers in lakes notice water racing over the swim hat with speed; whereas a wave from behind in the sea is like getting a wallop on the back of the head.

All this is the weight differential.

Within seawater there are also variables to weight. This includes waters that are saltier (more dense). For example, the Dead Sea bordering Jordan and Israel is the extreme. The southwest, west and northwest coasts of Ireland are heavy by nature of the depths up to 300 meters. The water running down the east coast of Ireland is fast and light to the touch due to its speed racing from the North Channel to the Celtic Sea. The density of the Atlantic on west coast of Ireland and the Irish Sea on the east coast of Ireland varies dramatically.

From a swimmer's point of view, the saltier the sea and deeper the water, the more buoyancy of the upward force on the swimmer. There is relative increased density in waters where our eyes sting and remnants of salt is left on our faces. The thicker the water, the harder it is to plow through, but the benefit comes with greater buoyancy, and thus greater the assistance. Swimming higher in the water allows the potential to surf and glide where swimmers lower in the water have to fight and push under the waves.

The tendency for solid substances to float or sink in water is measured by specific gravity.

In terms of buoyancy, people can be classified in two ways; floaters and sinkers. This is dependent on the various tissues within the body. Fresh water is assigned a value of 1.0. Substances with a value less than that will float and more than that will sink.

Fat tissue has a specific gravity of between 0.7-0.9. Bone is 1.9 and muscle 1.08. Dependent on the factors such as ratio of fat to muscle, the size of the individual, muscle mass, and the weight of the bones, the human body tends to either sink or float only slightly when in water, especially due to the combination of other factors such as density of the water, depth and weight.

Women have what is termed in diving as 'hollow legs' that describe the difference between males and females immersed in fresh water: male legs fall downward and female's remain buoyant.

The benefits of buoyancy in swimming are numerous, but what does that mean regarding speed advantage?

If you have a still fresh water and a still sea water area, there are variables such as tides, flows, the moon, and rips. None of this is visible from the surface for lakes are incredibly deceptive by their nature. Local knowledge is integral as lakes have eddies and return flows. That is, if a lake has a river running in and out, when the water tries to exit and there is not enough space, the leftover volume of water returns back down the lake.

Islands experience circular flows and can increase speed due to the tides. To compare the distance and time variable between two swims and try to determine the advantage of buoyancy between sea water and fresh water, I suggest the only clinical possibility would be in a shallow water beach front without movement and a dam where there is zero flow in or out that could influence the progress. Every other body of water has too many variables.

Copyright © 2008-2018 by World Open Water Swimming Association

A Thank You Gift from WOWSA


WOWSA is celebrating the
1-Year Anniversary of the monthly Open Water Swimming Magazine
by giving you a free copy of the anniversary issue.

Open Water Swimming Magazine Anniversary Issue
File Size: 13MB

FREE DOWNLOAD

INSTRUCTIONS:
Download the file to your computer, and then right-click to extract the magazine which is inside the zip folder. The magazine is in PDF format.

CLICK HERE to download your free copy now.

Open Water Swimming Magazine


Open Water Swimming Magazine

The Open Water Swimming Magazine is the monthly magazine entirely focused on open water swimming heroes and heroines of every age, ability, and background. Published by the World Open Water Swimming Association, the Open Water Swimming Magazine is a free benefit to WOWSA members.

WOWSA Member Benefits include 12 issues of the Open Water Swimming Magazine, the annual 276-page Open Water Swimming Almanac, a free listing in Sponsor My Swim, outstanding product discounts from FINIS, an entry in Openwaterpedia and more...
LEARN MORE

The Other Shore


The Other Shore follows world record holder and legendary swimmer Diana Nyad as she comes out of a thirty-year retirement to re-attempt an elusive dream: swimming 103 miles non-stop from Cuba to Florida without the use of a shark cage. Her past and present collide in her obsession with a feat that nobody has ever accomplished. At the edge of The Devil’s Triangle, tropical storms, sharks, venomous jellyfish, and one of the strongest ocean currents in the world, all prove to be life-threatening realities. Timothy Wheeler’s documentary brings Diana Nyad’s extraordinary adventure to life as Diana sets out to prove that will and determination are all you need to make the unimaginable possible.
LEARN MORE...

2014 Open Water Swimming Almanac



An Almanac for Open Water Swimming

An almanac is essentially a body of knowledge which is so complete that it enables people in different fields to make predictions about the future of their respective industries.

This, for example, was the purpose of the traditional farmers almanacs. It enabled farmers to determine as accurately as possible which crops to plant for the greatest harvests in a given year.

But the farmers almanac was just one example among many.
There are, of course, many different kinds of almanacs.

In fact, there is even one for open water swimming...

Preview the Open Water Swimming Almanac:
https://www.worldopenwaterswimmingassociation.com/preview-open-water-swimming-almanac


The trends are very clear.
The tide is rising for open water swimming.

SponsorMySwim.com

Open Water Swimming Event Sanctioning

World Professional Marathon Swimming Federation

Open Water Race Calendar

Coaches Education Program