All, Now that I'm awake.... Perhaps this might help some folks put into context what AIS can and cannot do. It's not my intent to beat a dead horse. These were some thoughts that came up in an offlist exchange that I thought might add more light than heat to this discussion. Item 1 is history, 2-12 are as I have personally observed them over the last 6 years and 30K miles of cruising (several trips up the Hudson to the Thousand Islands, the Great Loop, the A-ICW 9 times, the NJ ICW from Cape May to Manasquan twice, the Abacos and the St. Lawrence Seaway): 1. AIS was developed under SOLAS for COMMERCIAL SHIPPING, *not* pleasure craft. It is an international (SOLAS) safety standard. In the US, the FCC did not type approve Class-B (pleasure boat scale systems) AIS units until long after they were available from manufacturers; they came within nano-meters of not type approving Class-B in the US at all (for what I now realize were pretty good reasons!). They were "encouraged" to approve by Homeland Security, who thinks they can keep track of *all* boats with motors using AIS; just try to imagine that chaos!!! 2. Not all commercial vessels are required (by coast guard regulation) to carry AIS 3. Only a small percentage - the largest gross tonnage - commercial vessels actually carry AIS 4. Small harbor tugs and work barges *do not* carry AIS 5. Most Moran and McAllister ocean-going tugs do carry AIS; they do not - will not - respond to Class-B callers! 6. The Navy and the Coast Guard carry, but usually do not use, AIS (run in "quiet" mode); the bad guys might see them coming, dontcha know... 7. On the Inland Rivers, only large towboats that operate in the controlled ports of New Orleans and Mobile carry AIS; that's accounts for 75% - 80% of large river tows; Casino boats do not generally carry AIS. 8. On the East Coast A-ICW, only a very small percentage of commercial traffic carries AIS; only a slightly higher percentage on the gulf coast ICW, and the bulk of that in the area of New Orleans and Mobile 9. In NY Harbor, only a small percentage of commercial traffic carries AIS 10. Some of the Staten Island Ferries carry; some do not. All ferries or cruise boats carrying 150 passengers or more have a security zone associated with them, so if you're near one, AIS or not, you're already in trouble. 11. Water taxis and fast ferries from Atlantic Highlands and Weehawken *do not* carry AIS 12. Most large ships do filter AIS in harbor areas, and on the Chesapeake and Delaware Bays By far, the area where having an AIS receiver was of the greatest value to Sanctuary was on the Tennessee River and the Tenn-Tom Waterway, where we could call tows by name; it was also of moderate value in the Tennessee River Lake country. It was useless in Mobile Harbor because of the number of hits, mostly from moored ships. This is typical of all large harbors, including NY, Elizabeth, Baltimore, Norfolk/Portsmouth, Morehead City, Charleston and Savannah. It has never been of any value on the Neuse River, Pamlico or Albemarle Sounds, Cape Fear or Beaufort River, or Port Royal Sound. It is of little value on the Chesapeake and Delaware Bays, and Tampa Bay, where the big fellows all run in well documented channels. It is of no value on the Chesapeake Bay Rivers (James, York, Rappahannock, Potomac), the Gulf-ICW or in South Florida generally. It was of little value on the Great Lakes, except possibly for night crossings, I guess. That leaves the remaining issue of clutter. That's obviously up to each captain, but my advocacy remains with a dual-channel receiver, not a transponder. Just keep a good helm watch. At trawler speeds, that's plenty of safety margin! Jim Peg and Jim Healy aboard Sanctuary Currently at Charlotte Harbor, Punta Gorda, FL Monk 36 Hull #132 MMSI #367042570 AGLCA #3767 MTOA #3436