By Bob Currie, Recreational Boating Safety Specialist
U. S. Coast Guard Auxiliary Station Galveston Flotilla
For years now I have been telling everyone they need a marine VHF/FM radio to safely operate their boat near shore (within 20 miles) because cell phones are not dependable. Although everything above is still true, the Coast Guard has a new system that incorporates your cell phone.

Background
The Coast Guard has spent a couple of decades creating a radio network that uses marine VHF/FM radios to locate mariners in distress. The system has been working for a few years now. It guarantees that a one watt emergency radio transmission from any boat within 20 miles of any US shore will be detected and acted upon. Cell phones have always been unreliable for several reasons. First, their transmission power is too low to reach cell towers when out on the water. Second, cell phone signals cannot be triangulated like marine VHF/FM radios can be. The best we have been able to do now is locate the nearest cell tower pinged by the cell phone. But things have changed. Although the marine radio is still the best service for being located on the water in an emergency, new advances in cell phone technology now allow the Coast Guard to locate mariners in distress provided they have their phone properly set up.

The i911 Program
The i911 program allows Coast Guard watchstanders to use a mariner’s cellphone number to assist in finding their location for Coast Guard rescue crews to locate them faster. Once the number is entered, the mariner receives a text message authorizing them to share their location with the U.S. Coast Guard. Once shared, the internal cell phone’s GPS, which uses satellites to pinpoint the mariner’s location, is displayed on a screen for watchstanders to aid in the search for them.

Depending on the cell phone service, i911 can determine locations of distressed mariners from up to 15-20 nautical miles offshore (17-23 statute miles). This makes the i911 system’s range close to that of the Rescue 21 system, which uses VHF/FM radio frequencies to detect an emergency distress call activated by a marine radio.

Setting Up Your Cell Phone to Use i911
There is a catch to using i911: you must turn on your cell phone’s location services. It’s Easy. Below is a screenshot from my iPhone to demonstrate the procedure.

In order to find my Location Services, I went to Settings and in the Search Bar I typed in Location Services, and by golly it took me right to it. As the explanation says: Location Services uses GPS, Bluetooth, and crowdsourced Wi-Fi hotspot and cell tower locations to determine your approximate location. How approximate? Sometimes as close as 1 meter away from your true location. I think we can live with that level of accuracy.

So How Exactly Does i911 Work
The best way to demonstrate that is with a graphic:

click image for larger view

Summary
If you do not have a marine VHF/FM radio on your boat and you have an emergency, If your phone is properly set up with Location Services turned on then you can dial 911 and the Coast Guard may be able to locate you using the i911 system.

[BC: Apr-30-2024]