Photo via flickr by jurvetson
Humans are terrible swimmers, converting roughly 3 percent of their kicks, strokes and general underwater exertions into forward motion. We can boost our efficiency to 10 percent by adding fins, but dolphins, by comparison, can turn 80 percent of their energy into thrust. Not to be outdone, the Pentagon’s research wing, DARPA, is developing a contraption called PowerSwim that lets Navy SEALs and other combat divers swim faster, and with less effort.
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.
The goal isn’t to increase the total distance that personnel can cover, but to get them there more quickly, and with more energy.