Originally Posted by rebel heart
For commercial vessels that's one thing, but you made a statement that you "integrate the DCS into your navigation system". Plenty of pleasure boats (mine included) don't have navigation systems other than charts
and a handheld gps as well as other fixing instruments. That in and of itself seems to negate a lot of the benefit of DSC.
In the training videos I've seen, hailing someone via the MMSI takes much longer than simply grabbing 13 and hailing via voice.
DSC wasn't created because people wanted it; it was (as best I understand it) created by authorities to reduce voice traffic.
In regards to the "40 questions", I always thought a big part of that was to allow the USCG to fix your position by all those towers they erected in the last decade or so.
What does a DSC provide that a voice VHF if you know your position doesn't?
I will break this down a piece at a time.
Integration into a navigation system is a fringe befit not required for full use of DSC. Incoming DSC messages put messages on most chartplotters. Massage also appear in the VHF display. In your case you need only get the GPS NEMA RMC sentence data to the VHF which only requires a 2 wire connection.
My DSC has a phonebook in it to store MMSI which I think is common with class D VHF. I know the MMSI of folks I usually comm with. I preselect a working channel then select say Vesper in the phonebook and hit call. Even if the volume is turned all the way down on Vesper but the radio is on it rings and lets them know a comm is inbound. Since this is done over the reserved digital channel 70 no one else is aware of the call. With the DSC Auto Switch feature my VHF switches Vesper to my preselected working channel and we can talk once they turn up the volume. This offers some level of privacy if I select a working channel that is infrequently used in our area like say channel 71. BTW this type of call will go through even if someone's mic key is held open blocking voice hails.
It is all part of nations declareing Sea Area A1, AIS
, and GMDSS. You can look these up on Google
. Reduction in voice traffic is a secondary aspect as there is over congestion and DSC provides alternate mean for most voice comm including facilitating voice calls as explained above. This is also part of homeland security
, terrorism, citizen health
, less cost and any number of there justifications governments give for these sorts of things.
No the 40 questions are a checklist developed by lawyers and are more about protecting the CG should a lawsuit develop than fixing your position. Beyond that it is intended to keep comm with the caller open in an emergency
and get real time details, keep them calm and keep them engaged. If you have fully completed your MMSI application the mundane questions of the 40 questions are answered when you DSC VHF transits your MMSI as is done in all DSC traffic, they just look it up in a database only they and their international counterparts can access. I must stress that a free MMSI does not go into the international ITU database, only MMSI from the FCC are passed on to the ITU.
Like it or not people get rattled in an emergency, their higher brain (mammal brain) function shuts down. Now have the CG firing 40 questions about your boat
(reg numbers, color, length, etc), equipment
on it, where you are, where you are going, how fast you are going there, what the nature of the call is while you are still trying to operate the boat and it goes south real quick. A DISTRESS DSC alert sends your MMSI, your position and on some radios you heading and speed with the message automatically and continues to do so until the CG acknowledges the DISTRESS alert. Further anyone who has your MMSI, in this case the CG has it, that wishes to can poll
your radio and find out where it is. If that is repeated enough you eventually will have a plot on them. Your radio can be polled for its position without you having to do anything if you know its MMSI. Have you ever listened in while someone tried to read their vessel reg numbers and/or lat/long over the radio, especially if there is engine
or other noise
in the background or the comm link isn't real quiet? Now throw in a serious medical
emergency or vessel in parle.
So yes DSC is a whole lot better than voice in this and a whole lot of other ways other than DISTRESS. I really do recommend reading the radio's manual for DSC features as I have only covered a few here, you paid for it why not use it the MMSI is free. I think you will be amazed with all the DSC features you paid for and are not using.
Why so hostile about getting you free MMSI, programing your radio and connecting it to a GPS with 2 wires? Is it because the gov didn't ask your opinion first or you resent excuses for yanking on the radio are being reduced?
Mark Fay S/V Enough MMSI 367188830