It all comes down to "are you going to believe what you see or what the AIS system tells you" as others have said AIS is a good technology BUT with massive limitations not least it relies on the actions of someone else to make it work for you - and its not switched on by everyone who has it so at the momement its no good, relegated to the level of a novel chocolate teapot used to store boiled sweets. eyeballs and radar are still the only sensible options - but that could change if AIS became believable. oops thats one "if" too many. .