<John wrote: A glance at the AIS display (on CE) showed the triangle symbol facing the wrong way! Further investigation showed that all the data was correct, including course, but his heading was fixed at 17 degrees! So we learned something today,> I have reported on this before. If we look at the list of boats that show up on our AIS window on Coastal Explorer we can always find one or more whose data is not correct. Most are operator input errors but some are caused by the installation or equipment failures that are not noticed by the operator. There are several boats that have a 180 degree error in their heading information. I have spoken to them about it but they don't seem to either care or get it fixed. Hmmmmm, this would tend to imply that there is no enforcement of the integrity of the AIS system. I know that the Coast Guard doesn't check this as part of their "boarding and safety checks of vessels as they boarded one of the ships, Sea Searcher, that has an 180 error last week off St Thomas and it still has the same error. So I guess I would ask the question: Who has responsibility for the enforcement of the AIS data integrity/stream? There doesn't seem to be any kind of "self test" of the data that is actually being transmitted and thereby received by other vessels. One needs a hand held or portable AIS receiver to perform this function. At the moment I know of no commercially available unit but it wouldn't be hard to make up one that would plug into a laptop.....in fact I have an extra SR161 that I think we can do this with. Pretty limited use tool but it could be invaluable. In talking with a couple of installers of Class A AIS gear they have nothing other than asking other ships for a report on the data they receive. So once again as John has confirmed AIS is a great aid but like any other aids to navigation it needs to be confirmed with other forms of input, visual, radar, communication, etc. As always YMMV Cheers Dave & Nancy Swan Song Roughwater 58 Caribbean Cruise '07