Dilemma: FCC and MMSI rules Jeopardize Safety

[jssailem]

Spoke with SH tech and learned the same. If hand held and base station use the same MMSI the DSC does not talk together. Sure the other listeners may hear the call but not the two units. Like picking up a land line in the kitchen and trying to call the bedroom phone on the same line.

Tech did say some of the SH dealers have the software to erase the MMSI on your unit. Saving the cost of shipping the unit back to their Southern Cal offices.

 

[Jackdaw]

Also in this thread, there seems to be a mixing of....
1) Boat Distress 2) Man Over Board 3) Abandon ship

IMHO all of those could have different Radio needs. Note: AIS is probably not among them.

I'd disagree with that. Of all the location sending VHF technologies, AIS is unique because it automatically and continuously updates the position. All other send once. Very handy in a MOB situation, in particularly when the casualty is unconscious.

 

[Gunni]

The recommended AIS install is with a dedicated AIS antenna. If a shared antenna is being used and you are transmitting on the VHF you will step on the AIS reception. Just saying.

 

[Skipper]

The recommended AIS install is with a dedicated AIS antenna. If a shared antenna is being used and you are transmitting on the VHF you will step on the AIS reception. Just saying.

Unless you have a SH GX2150 or the new GX2200. AIS is integrated, and uses the same standard VHF antenna. These radios are Rx only for AIS.

Edit: which doesn't necessarily make your statement untrue. :-D
Although I've never had any AIS interruption that I've noticed.

 

[JohnShannon]

Transmit for sure will stop AIS reception. However what % of the time do you transmit? Not much. I think for instance the AIS SART is transmitting every 2 seconds. Otherwise stuff that doesn't move transmits I think every 5 min and the faster you move the faster you transmit which keeps the position info relevant.

 

[JamesG161]

Very handy in a MOB situation, in particularly when the casualty is unconscious.

I had to re-read about AIS. It appears to be a collision avoidance system when radar combined and all vessels have AIS.

I guess I miss understood how a MOB would have AIS on his person.

Is this new, like an EPIRB?

My MFD has a MOB button when pushed records the GPS position of the MOB and will calculate his drift based on wind and current data. You would radio both rescue MOB coordinates to USCG.
Jim...

 

[Jackdaw]

I had to re-read about AIS. It appears to be a collision avoidance system when radar combined and all vessels have AIS.

I guess I miss understood how a MOB would have AIS on his person.

Is this new, like an EPIRB?

My MFD has a MOB button when pushed records the GPS position of the MOB and will calculate his drift based on wind and current data. You would radio both rescue MOB coordinates to USCG.
Jim...

At its core, AIS is very similar to DSC. Both encode MMSI-based digital data onto an analog VHF signal. The AIS spec however allows for regular, automatic updates on BOTH SIDES of the standard. This allows an AIS equipped plotter to show a continuously updated ACTUAL position of the MOB, even if they are drifting.

Devices like the RescusME AIS rely on this to send a stream of AIS position reports when activated. It also sends a DSC mayday as well.

AIS can contain other data about a ship and its voyage which are not needed for MOB scenarios.

 

[bawlmer]

West Marine sells a device that clips to you and transmits AIS if you go overboard. It puts the MOB on your chartplotter so you can find and rescue him/her. It also has a antenna that pops out that supposedly increases your range so other vessels can see you on their chartplotters as well. Sounds like a good idea.
I sail in a very busy harbor and I use my AIS a lot. It tells me where all the big ships are and if any are coming out into the main harbor. Imagine a semi truck running a stop sign in slow motion and putting himself right in front of you. AIS gives me a heads up on those occasions. AIS updates frequently and transmitting on your VHF may interrupt one broadcast but It has never been an issue. Speed and direction info have never been skewed due to me transmitting.