UAVs are becoming more popular for maritime patrol. Three years ago, using UAVs purchased from Israel, India formed its first UAV maritime reconnaissance squadron. The unit has eight Searcher II UAVs and four Herons. The Searcher II san stay aloft for 16 hours at a time. The Heron is similar to the U.S. Predator, and can stay up for fifty hours at a time. The radar and vidcam sensors enable the UAVs to provide unprecedented coverage on short notice. Israel is also using a version of the Heron for maritime reconnaissance.
Israel, which also uses UAVs for maritime recon, is particularly eager for these UAVs to succeed at this role, for that would open up a huge market for Israeli made UAVs and sensors. Israel has been the leader in UAV technology for over two decades, and has been supplying India with UAVs to the Indian navy for six years now.
The U.S. Predator is now available equipped for maritime reconnaissance. This includes a sea search radar and electronics that can read the transponders (broadcasting speed, direction and identity) that all ships over 300 tons (gross). These navalized Predators can be switched between land and naval sensor gear in a few hours. The U.S. plans to use Predator UAVs to patrol coastal waters and the Caribbean. The U.S. is also equipping the ten times more expensive Global Hawk for maritime reconnaissance. While Predator or Heron are good for coastal recon, Global Hawk can cross the Atlantic or Pacific, and is thus able to sweep large swaths of the high seas.
UAVs used for maritime search are much cheaper, can stay in the air longer and can even carry weapons (one or two Hellfire missiles). The operators are ashore, and can work in shifts to monitor the sensors. In any event, the sensors are increasingly using pattern recognition software, to catch things that a human observer might miss.