September25, 2008:  The U.S. is getting some valuable practice hunting submarines by searching for the increasingly numerous drug smuggling semi-submersible boats carrying cocaine from South America. U.S. anti-submarine aircraft are honing their skills at spotting very small objects at sea by spotting heat.

Between 2000 and 2007, 23 of these drug boats were spotted. But so far this year, over 60 have been seen or captured. The two most recent captures were the result of intelligence information at the source, not air and naval patrols out there just looking for them. These boats are hard to spot (by aircraft or ships), which is why they are being used more often. It's very difficult to pick the boats up with airborne radar, but heat sensors are another matter. The boats engines, and the crew, give off heat, and there are airborne sensors that can detect that. The U.S. Navy will not reveal the range and sensitivity of the infrared (heat) sensors used on its P-3C maritime patrol aircraft, but apparently it's possible to detect these boats from their heat. the P-3C has a cruise speed of 610 kilometers per hour, endurance of up to 13 hours. Flying a few thousand meters up, and with a heat sensor with a range of 5-10 kilometers or so, a P-3C can cover a lot of ocean. But the drug boats come up from Colombia, often 500 kilometers off the Central American coast. That's a whole lot of ocean.

These are not submarines in the true sense of the word, but "semi-submersibles". They are 30-60 foot fiberglass boats, powered by a diesel engine, with a very low freeboard, and a small "conning tower", providing the crew (of 4-5), and engine, with fresh air, and permitting the crew to navigate the boat. A boat of this type is the only practical kind of submarine for drug smuggling. A real submarine, capable of carrying five tons of cocaine, would cost a lot more, and require a highly trained crew.

The semi-submersibles are built, often using specially made components brought in from foreign countries, in areas along the Colombian coast, or other drug gang controlled territory. Russian naval architects and engineers have been discovered among those designing and building these boats. Based on interrogations of captured gang members, these subs cost over $600,000 to construct, and carry up to ten tons of cocaine.

At one point it was thought that as many as half of them were captured or lost at sea. But this is apparently not the case. That's because most of these subs are built for a one way trip. This keeps down the cost of construction, and the cost of hiring a crew (who fly home). That one voyage will usually be for about a thousand kilometers, with the boat moving at a speed of 15-25 kilometers an hour. So the average trip will take a few days. But going to Mexico takes about a week, with additional fuel and crew supplies reducing the amount of cocaine carried.

These subs are not stealthy enough to avoid detection all the time, and the U.S. is working to tweak search radars, and other types of sensors, to more reliably detect the drug subs. The U.S. Navy is also going to try using Predators, equipped with a maritime search radar. The heat given off by these boats is comparable to what a diesel-electric sub puts out when semi-submerged (with just its schnorkel, on top of the conning tower, above water to provide air for the crew and the diesel engine). There is technology that can decrease that "heat signature" and the drug gangs may be able to get help from their Russian technical advisors on that subject as well. And then the U.S. P-3C crews get a chance to defeat the improvement. In any event, the U.S. is gaining valuable experience searching to small objects at sea.