In Praise of AIS

There are plenty of penny pinching yachties that either do not have AIS equipment or opt for ‘receive-only’ systems. Some even imagine that internet based ship tracking Apps such as Marine Traffic and Shipfinder are free equivalents.

The bloke indicates a cargo vessel in nearby shipping lane

For the uninitiated, AIS is short for Automatic Identification System. In essence, all commercial vessels are required to emit a signal that not only uniquely identifies their vessel by name, callsign and direct radio calling channel, it also gives details of vessel size, origin and destination, speed over ground (SOG) and their heading. The system also responds to nearby vessels calculating closest distance of approach and estimating the to time this potential event. In instances where courses are calculated to intersect, a collision alert is generated. It is an enourmous help to situational awareness and safety. Many, but not all coastal and off-shore sailing vessels also use Class B AIS. Most new marine VHF radios are now equipped with both DSC (Direct Selective Call) and AIS receivers. These do not however emit a signal rendering the vessel visible only to the Class A Eyeball. Extra equipment is needed for an 'emitting' AIS and in the 10 years we have had ours, prices have dropped dramatically, yet still the AIS emitting yatch list is not comprehensive.

Class A Eyeball detects vessel bearing down

Given that we ourselves have spent $1,000’s on ‘Safety’ equipment that we hope never to use; think life raft, EPIRB’s, flares, life rings, drogues, dan-buoys, life-jackets, etc... there might be a case of spending fatigue on this category of paraphernalia. However, this is actually one bit of kit that you actually get to use all the time; and is a huge help, even outside of an emergency!

Class A Eyeball notes nearness of cargo vessel followed by yet another.

As mentioned, some folk imagine that internet based Apps that display AIS information are adequate and being FREE are a cheeky alternative. This is a classic case of ‘you get what you pay for’. If you are beyond a shore based VHF receiving station or not within range of a vessel that acts as a beacon, these Apps will be blind to the actual existence of vessels in ones vicinity or their location information is old and not in ‘real time’ - which of course is the whole point- accurate situational awareness.

AIS display - 0.6nm can become 0.0 with the next wave or puff of wind. 2.0nm is far more acceptable.

Let’s set aside for now the fact that commercial fishing vessels only transmit their location to State Fishery authorities. It is in their commercial interest to act covertly from their competitors. Fishermen do ‘see’ our Class B AIS recreational signal though and we have on occasion been radio’d by name and asked to watch out for their nets. This is no easy thing since it’s generally nighttime. For instance, trawlers with limited maneuverability have requested a course change from us. We’re always happy to oblige since they are working mariners and we also value our propeller, rudder and keel!

Much too close for comfort

Sailing recently, back towards the mainland coast from Lady Musgrave Island, it was necessary to cross a very busy shipping lane taking, primarily coal and gas, cargo ships into and out of Gladstone Harbour. It was a drifter and sailing in 5kts breezes from the stern, we were goose-winged with even our inner headie set for good measure. We had all day to cross the 30nm and 2-3kts of speed was all we could manage without assistance from our motor. Crossing the shipping lane took what felt like 'forever'.

We can hear the thump of the propellers from about 1nm.

Our AIS came into its own. We made radio contact with the vessel that was bearing down on us to confirm that we were monitoring their movements (speed, course and relativity to our own) and we were very pleased to have it confirmed that they were aware of and monitoring us too! From the height of a ships bridge deck there is a visual ‘black spot’ and small craft like ours are obscured by the ships bow, on-deck super structures or container stacks. A fibreglass boat does not reflect radar signals very well either. In the end, this vessel not only made course adjustments but also speed adjustments; slowing down and speeding up - we just couldn’t seem shake the 0.0nm closest point of contact. The vessel behind it heard our communications over Channel 16 and did the same without needing to be contacted. We were quite prepared to change course, stop or fire up the engine, but it wasn’t required in the end. When they were abeam of us we radio’d to acknowledge their courtesy.

MV Gaslog Geneva steaming away

Obviously, boats have been avoiding each other for centuries but waterways are becoming more congested and the AIS kit is a worthwhile safety spend that you will definitely use - and well outside circumstances of a critical emergency.