The collision-avoidance system is being used to send inappropriate text messages between boats
The Automatic Identification System has proven useful in collision avoidance, but as with any new technology it has had some hiccups as mariners learn to use it and, in some cases, continue to misuse it.
"My guestimate is that 30 percent of the safety-related text messaging [using AIS] is inappropriate," says Jorge Arroyo, the Coast Guard regulatory project officer for AIS. Like folks who misuse VHF channel 16 for chitchat, mariners have taken to using the AIS text-messaging feature to jawbone about everything except what it's supposed to be used for - short safety messages up to 156 characters, usually sent to exchange information between vessels in passing situations. It's not supposed to be used like Twitter.
Luckily, Arroyo says, the AIS chitchat so far is "less than on the radio."
Used for collision avoidance and port and coastal security, a boat's AIS transponder sends out a continuous stream of information about the boat's position, course, speed, heading, identity and other data. Equipped with AIS, skippers can "see" each other on the chart plotter or PC, and have navigation information on hand about each other.
In a May 27 safety alert, the Coast Guard advises mariners to use it to augment their situational awareness but "strongly reminds" them not to use it to replace other important navigation tools. The alert says AIS text messaging does not relieve vessel operators of the requirement to keep a radio watch on VHF channel 16, or to use sound signals and display lights or shapes as required while navigating. It also warns mariners not to rely exclusively on AIS messaging in an emergency situation.
AIS is very helpful in alerting other vessels of your situation, Arroyo says, but the Coast Guard doesn't have the resources to monitor AIS messaging, so an AIS message "may not be received, recognized or acted on" by the Coast Guard, according to the safety alert. Commercial vessels should use their Global Maritime Distress Safety System's emergency messaging, which the Coast Guard does monitor. Pleasure boats can send a mayday over VHF, use a signal flare, activate an EPIRB, or send a distress signal using a VHF equipped with digital selective calling.
"What we don't want is for people to rely on AIS as their [primary] distress alert," Arroyo says. "We're not monitoring it and we don't have the capability to monitor it."
The Coast Guard, however, says AIS emergency messaging can be a good backup to other emergency alerts because it can be seen as a symbol on radar or chart display as well as read as a text message by other AIS users within VHF range. "It's not your first means [of calling for help], but you should use it," Arroyo says.
And, finally, the Coast Guard is concerned that data embedded in too many AIS messages is flawed because operators have not properly programmed basic information into the transponder. Either the static data (MMSI number, radio call sign, vessel name, type and dimensions) is inaccurate; the dynamic data (navigation status, destination and time of arrival) are out-of-date; or navigation data (location, heading, speed and rate of turn) are missing because the AIS isn't properly linked to the vessel's navigation system.
Arroyo says mariners must make sure static data programmed into the transponder at the time of purchase is correct, dynamic data is updated before every voyage and the transponder is correctly connected to the navigation system.
Most commercial vessels must carry AIS and use it to operate in busy ports and shipping channels. Some pleasure boats also carry it to help them steer clear of commercial vessels, though they are not required to. Arroyo says there are about 40,000 AIS units registered to U.S. commercial vessels and 1,000 - mostly less expensive Class B units, which do not meet international requirements - registered to pleasure boaters. Arroyo says a few manufacturers already are integrating AIS receivers into their VHF radios so that boaters with a chart plotter can use AIS to track commercial vessels within VHF range. Boaters also can buy just an AIS receiver.
"Eventually this technology is going to trickle down to most boaters," he says.
This article originally appeared in the September 2010 issue.