There is a bit more to it.@gmacd81 - Is Rescue 21 able to detect your position if just hailing over Ch16 on a DSC radio, or do you need to push the DSC distress button for Rescue 21 to see your position?
- The boat must have a DSC enabled radio; you will know this simply by it having the red distress button. Most all modern hard installed VHF radios have DSC.
- You must register and obtain a Maritime Mobile Service Identity (MMSI) which is a nine digit number that is then entered into the VHF. Once the number is entered it is permanent and cannot be changed unless the VHF is returned to the manufacture. If someone (previous owner) has already obtained and loaded the MMSI into the radio it needs to be transferred to you the owner of the vessel. There is a process for that.
- The VHF must be integrated with the GPS so the DSC has GPS location data. Some VHF radios come with internal GPS but most are externally integrated via NEMA 0183 or NEMA 2000.
The VHF will then continuously transmit the distress signal with MMSI data and coordinates until someone acknowledges, then the VHF will automatically switch to Channel 16 at which time the nature of the distress can be discussed. If no one on the distressed boat responds on CH 16 (Captain is down for example) the Rescue 21 system still responds to the emergency.
The Rescue 21 system is integrated with the radio's MMSI registration and when a distress is transmitted the GPS coordinates, the registration data for the boat, and registrant's name are received by Rescue 21. Note also that the VHF transmits at maximum power on DSC and due to the digital nature of the signal the transmit distance is greater than the other simplex voice channels.
There are other desirable features for DSC like ship to ship private calling. Consider your MMSI your cell phone number. So, if you have a friends MMSI and you want a private two way call then you can select DSC Call from the VHF menu then enter their MMSI then select the channel you desire to have the conversation on and then transmit. Your friend's VHF will "ring" much like a telephone and when they pickup and acknowledge both VHF radios automatically switch to your selected channel then you can have a private conversation. Due to the digital nature of the DSC even if someone else is monitoring the channel you are on, they will not hear the conversation.
Regardless, hynespa, I like your reference card and if you don't mind will plagiarize but probably break it up into a couple of cards. I'll probably have a stand-alone emergency equipment card which will be placed in several locations on the boat. If you have your MMSI registered the emergent condition process on your card can be simplified. But, knowledge on using CH 16 for Pan Pan or May Day by passengers is also important.
Tom