Digitally see and be seen on the water
The Automatic Identification System, or AIS, was first implemented in the early 2000s to improve safety on internationally traveling ships. Using ordinary VHF antennas, ships are able to automatically communicate name, position, heading, destination, type of vessel, rate of turn and other useful information. As more cost-efficient units became available recreational boats starting equipping this technology. With an AIS system onboard a pleasure craft is automatically sending out its name, position, heading, speed, and other vital information about once every 30 seconds. Other boats receive this signal and can view these 'targets' on their chartplotters. Newer chartplotters can calculate any collision risks and sound an alarm alerting crew of any threat. Today virtually all commercial vessels are required by the Coast Guard to have an AIS system.
AIS uses a boat's VHF antenna to send and receive signals. The antenna can be shared with a VHF radio or a separate dedicated antenna can be used. The antenna then connects to a 'black box' style device hidden away that sends and receives signals. The AIS device is then connected to the chartplotter where other vessels appear as targets that can be overlayed on radar or chart screens.
Alert any equipped vessel in an approximate 20 mile radius of your presence, direction, speed, and name.
Modern radars can determine direction using calculations that update with every few spins of the array. AIS receives heading from the actual vessel that is moving.
Contact other vessels by name! Instead of describing the other boat's lat/long, simply hail them by name.
A boat's Maritime Mobile Service Identity (MMSI) is displayed on AIS as well. Using this 9-digit number a Digital Selective Call can be place to actually ring their radio like a telephone!
Personal man-overboard AIS beacons are one of the best safety tools for accidental trips in the ocean. The origin vessel and any boat in the area will be alerted to the individual in the water.
Anyone who has traveled along the shores of Southern New England knows the prevalence of fast-ferries. Traveling sometimes over 25 knots, the ferries can seemingly come out of nowhere. By tracking them on AIS there's no more surprises.
For docked boats hooked to power, a constant transmit allows at-home owners to view their vessel from AIS tracking websites and smartphone apps.