23 November 2007

Swimming Faster than You Ever Thought Possible

The problem with human swimming is that it is so inefficient! Only 3% of our efforts actually go into forward swimming force, and even with a good pair of fins we are only 10% efficient moving through the water. What if we could swim more like dolphins?
.... the Pentagon’s research wing, DARPA, is developing a contraption that lets Navy SEALs and other combat divers swim faster, and with less effort.

Instead of kicking, PowerSwim calls for a kind of undulation as its hinged foils pivot up and down. Similar to the way a dolphin or tortoise pumps its fins, this motion generates both lift and thrust. And while artificial fins operate within the swimmer’s own wake (they form a kind of expanding cone, starting at a swimmer’s shoulders), the PowerSwim’s lead foil—or propulsor foil—sweeps through the water just outside that wake.

When used properly, the device allows swimmers to cover a given distance up to 150 percent faster than with fins, while using the same amount of energy. Much of that boost in metabolic efficiency is due to the muscle groups used. As DARPA program manager Barbara McQuiston explained, the swimmer is essentially relaxing into a slightly bent position, instead of forcing or pushing the foils through the water. This takes the emphasis off the small muscle groups used to kick, and allows larger muscle groups, such as the glutes and quads, to take over. During tests, it typically took around 2 hours for Navy SEALs to fight the urge (and years of training) to move forcefully and learn the PowerSwim’s unique motion.

While this swimming technology was developed for military divers and swimmers, there is no reason why the rest of us cannot take advantage of a good idea. It appears likely that the swimmer's head would have to remain under water, so the need to breath underwater has to be addressed with compressed air, snorkels, gills, or other devices.

Adventurous swimmers who want to swim great distances might tow a raft containing food and gear. If the sea level of Earth rises as precipitously as many of the doomseekers of CAGW appear to wish, this sea level rise combined with "peak oil" might require a lot more swimming for coastal residents. Many people currently living on the mainland may soon find themselves living on an island. When that happens, if we no longer have fuel for engines, swimming or rowing might be the last resort for a daily commute.

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