APRS is the perfect tool for tracking boats and passing traffic to an from boats underway. The author has 20 years NAVY experience with tactical radar, data displays and HF communications. APRS was designed to operate continuously in the background and provide connectivity between widely dispersed stations. Our experience with APRS on the 25 Naval Academy boats on summer cruise, is that boats transmitting their positions and status once every 15 minutes have a 90% chance of being seen at least once every 4 hours, 24 hours a day. That improves to 98% chance during daylight hours!
PROPOGATION STATISTICS: A secondary benefit of APRS is its HEARD display that keeps statistics on the number of packets heard from each station over the last 24 hours. This display is a perfect display of HF connectivity between stations throughout the day.
WATERWAY NET OPERATION: There is already a national APRS position reporting network operating on 7.085 and 10.151 LSB. See HF.HTM. All boaters and Recreational Vehicles are welcome! Once you are tuned in, execute the OPS-QUERY command which will request position reports from everyone on frequency (over the next 2 minutes). Be patient.. Even without a Query, all stations will transmit their positions once every 15 minutes...
APRS BOATERS NET: Jim, WB4GQK maintains a tracking list of 29 vessels for the Maritime Mobile voice net. Generally they transmit between 0800-0900 EDT via msg to WB4GQK and shut down as soon as they see an ack. You should be able to see the vessels in the P.R. and Virgins. There have been 5 transmitting from Venezula and Trinidad. His station runs daily from 0600 to 2200 EDT. Most of these cruising Hams have his phone number for family and close friends. ..APRS is serving another great service. 73 de Jim WB4GQK@W4DPH.#TPA.FL.USA.NOAM
POSITION REPORTING: APRS will automatically report your position and status as well as send and receive messages. If you turn off your PC computer, APRS places your position report in your TNC BText so that your TNC will continue to report your last known position once every 15 minutes or so. This Beacon only contains your Position and words to indicate that your APRS program is not running. If you want your TNC to automatically report your position AND some meaningful status info, you can enter your LAT/LONG and additional comments manually into your TNC BText before Quitting APRS.
GPS/LORAN AUTOMATIC REPORTING: With the optional APRS $9 GPS registration APRS can report your real-time position automatically. Simply connnect your GPS/LORAN NMEA-0183 output to your second PC COMM port. APRS will automatically update your position report. You can also do this without APRS and a laptop, by using any of the new GPS capable TNCs (be sure it is HF capable).
OBJECT REPORTING: ANY APRS station can report the position of any other station manually by simply placing the station on his map. Be sure to enter a course and speed so that all APRS stations will dead reckon you between posits.
DEAD RECKONING: APRS automatically dead reckons all position reports that have a course and speed. DR'ed stations show up in light blue color and have an anchor line back to their last reported position. To defeat dead reckoning toggle the CONTROLS-DR command. When moving the cursor to select stations on the map display be sure to select the "anchor" position, not the dead reckoned position. If you are seeing all new posits being instantly dead-reckoned, then your PC clock is off. FILE-SHELL-DOS to re-set your clock or ue the alt-SETUP-GPS-TIME command to have your PC automaticlly synced to the the next GPS posit heard.
TRACK HISTORIES: APRS automatically saves all track histories to disk. To reduce redundant data, APRS normally filters out all positions from the same station that are within 80 yards of each other. This accounts for the normal randomness of GPS. This filter can be turned off, so that all positions (that are not exact duplicates) will be saved. These track histories can be replayed at any time, either from memory or from file.
WEATHER REPORTING: The automatic home WEATHER interface to APRS permits shore stations to report weather conditions to boaters map displays. Also, manual WX Object reporting is very handy for showing the movements of hurricanes and tropical storms. Uplinked by any station, these dozens of WX objects will also be dead reckoned on the map so you can see storm movements. Even these home WX stations can be installed on your boat and as long as you have an electronic compass connected, APRS can convert your realative wind diretion to TRUE!
SYMBOLS: In addition to a number of Weather symbols, APRS has two boat symbols (Sail & Power) plus a Buoy and Lighthouse symbol. The Buoy can be colored red or green if it is added as a symbol to a map label. See SYMBOLS.HTM.
WATERWAY NET OPERATIONS: Boats that are HF packet capable should routinely report their posits via APRS. This will reduce loading on the voice net so that it is better available for passing voice traffic, and for posits from non APRS stations. One APRS station can volunteer daily to uplink the voice position reports into APRS from his display by placing them on his screen as OBJECTS. Once these reports are being uplinked into the APRS net, any other APRS station can assume reporting responsibility for that OBJECT (station) simply by uplinking a later report.
WATERWAY NET MESSAGE TRAFFIC: All APRS stations should also maintain an up-to-date STATUS beacon using the INPUT-MY-STATUS command. Secondly, APRS stations can send short message lines to any other stations. These short messages can be used throughout the day for making schedules for voice contacts on 7268 without the stations having to listen to the HF freq all day. There is also a several line BULLETIN capability for putting out information to all monitoring stations. After HF voice operations, stations that are packet equipped can just turn the volume down and park the HF rig on the APRS frequency instead of turning it off. This will keep them fully informed and reported without any additional effort.
APRS NET FREQUENCIES: All boaters are welcome on the 10.151 LSB APRS National tracking net. YES, THIS IS IN THE BAND! See my HF.HTM
NAVAL ACADEMY APRS NET: During summers only, the Academy operates an APRS net on a 6 MHz navy frequency for tracking its 20+ boats on summer cruises. Serious HF APRS shoreside stations with NAVY credentials might be useful for assisting the Academy in passing traffic. If you are interested, please contact WB4APR. APRS is also used by the Afloat MARS net for reporting the positions of all stateside MARS stations on frequency for passing phone patch traffic. The US Navy ships, of course, do not report their positions for security reasons, but use APRS to show who is listening stateside. For more info on the Navy MARS APRS afloat net, contact N1BFQ in New Hampshire.