Not the graetest news, but here is an excerpt of an article from BOATSAFE.com:
Although commercial ships over 300 tons are now required to monitor the DSC Radio reserved Channel 70 for distress calls, the US Coast Guard is still monitoring Channel 16. As the Coast Guard updates and upgrades their equipment, they should be monitoring DSC Channel 70 in many areas by 2002-3 and be fully functional and compliant by 2005-6. The USCG's equipment up grade will include:
DSC capability to send or receive calls on channel 70
* Eliminate the 65 gaps in current VHF coverage in the US
* Provide direction finding capability to trace a garbled radio signal to within 25 miles
* Provide playback of VHF voice or digital calls
* Provide automatic tracking of USCG ships and aircraft on search and rescue missions
There have been recent incidences where commercial ships have picked up the "mayday" calls on Channel 70 and relayed them to the USCG.
The DSC radio feature is part of the Global Maritime Distress and Safety System (GMDSS). This system was put in place by international treaty in 1988 and all seagoing nations including the US will be GMDSS compliant by 2005-6.