Fleets of robot submarines will change oceanography ECONOMIST Jun 9th 2012
SAILING the seven seas is old hat. The latest trick is to glide them. Sea gliders are small unmanned vessels which are now cruising the briny by the hundred. They use a minuscule amount of power, so they can stay out for months. And, being submarines, they are rarely troubled by the vicissitudes of weather at the surface. Their only known enemies are sharks (several have come back covered in tooth marks) and fishing nets.
Sea gliders are propelled by buoyancy engines. These are devices that pump oil in and out of an external bladder which, because it deflates when it is empty, means that the craft’s density changes as well. This causes the glider to ascend or sink accordingly, but because it has wings some of that vertical force is translated into horizontal movement. Such movement is slow (the top speed of most gliders is about half a knot), but the process is extremely efficient. That means gliders can be sent on long missions.
Our Ocean Pasture Salmon Restoration Project has two Slocum Gliders provided by the Canadian Institute for Ocean Gliders. We’ve been the first Canadian business to take advantage of these dream machines to develop new technologies for stewarding ocean pastures. Our extensive use of two gliders and the longest duration research ship accompany them is making scientific history. Spectacular discoveries have resulted from the combined glider and ship board studies which will change the way the world of ocean science looks at our ocean pastures.
You can read what the Economist says about our dream machines here…
Ten years ago there were fewer than 30 gliders in the world, all built either by academic institutions or the armed forces. Now there are at least 400, and most are made by one of three firms: iRobot, whose product is called, simply, Seaglider; Teledyne Webb, which manufactures the Slocum Glider (named after Joshua Slocum, the first man to sail solo around the world). Gliders, moreover, give a continuous view of what is going on, rather than the series of snapshots yielded by equipment lowered from a vessel at the surface. Besides tracking pollution, watching volcanoes and measuring icebergs, they are following fish around, monitoring changing temperatures in different layers of seawater and mapping the abundance of algae.
Gliders are also quiet—so quiet that, as one researcher puts it, you can use them “to hear a fish fart”. This was demonstrated by a recent project run by the University of South Florida, in which a glider successfully mapped the locations of red grouper and toadfish populations on the West Florida Shelf from the noises the fish made.