I think an AIS receiver is essential, particularily on the inland rivers. It is possible a sinking last year could have been avoided had the captain had an AIS and was using it. (Details at http://greatloopcruising.com/blog_direct_link.cfm/blog_id/47405) . I also would like to submit my AIS Ettiquette post primarily for AIS transmit owners based on two years experience with AIS. This year at the AGLCA Redevous there were only 3 boat owners that couldn't figure out how to turn off their transmitters. Last year there were at least 20 so the word is getting out. AIS Etiquette AIS (Automatic Identification Systems) are now being installed in many cruising boats. AIS has tremendous benefits in knowing where tow boats are travelling on river bends and large fast ships on coastal waters. AIS gives the name of the vessel, its position, heading direction, and speed on a display at the helm. Boaters that have installed a transmitting AIA Automatic Identification System should learn the proper etiquette. 1. It serves no purpose to keep the AIS transmitter turned on when your boat is tied up to a dock. Leaving it turned on clutters up the display of other boaters passing by or entering the same harbor. 2. The process for turning off the transmitter may be difficult. Manuals need to be consulted and if all else fails then turn the circuit breaker off that feeds the transmitter. 3. AIS receivers have an alarm that turns on if a transmitting vessel is nearby. In the morning turning on the receiver sounds the alarm if any other boat in the harbor has failed to turn off their transmitter. On Garmin units the AIS alarm sounds as soon as the receiver is turned on. After a few seconds the most ungodly screams announce an immediate collision is about to occur and the display shows a ship wreck symbol on top of everything else. Bob Duthie Katy Leigh 36 GB Classic bob@duthielearning.com <mailto:bob@duthielearning.com> blog at greatloopcruising.com