AIS with GPS, WiFi, Splitter and SART 970

[ShinyShoe]

Sorry, I should have said I have a vhf with no dsc.

So you spend all the extra money on the SART function but could have spent it on a DSC VHF?

You are in distress, struggling with COMMS for some reason. You hit the SART button and I pass by you because I don't have AIS receiver or have one but it doesn't understand distress message, or I have it switched off because I'm in open water and can see what is around me.

I didn't think AIS SART's got a CG response but I could be wrong. I suspect it depends on location, vessel and what else is going on. Is the CG AIS coverage as good as DSC?

Multiplex or whatever it is called on one VHF aerial... ...am I right in thinking if you are voice transmitting it can't AIS receive or transmit. So the Sh17 it hitting the wind turbine and you are in heavy voice comms with CG, helo and LB etc. Does that affect your AIS updates? Or it is a perfectly normally day. Lots of shipping around. AIS would be useful. But there is lots of voice traffic. Can it receive both at the same time?

 

[LadyInBed]

So you spend all the extra money on the SART function but could have spent it on a DSC VHF?
. . . .
. . . . . . Can it receive both at the same time?

See #18, pvb has it in one.
As I understand it, you follow up a DSC with a voice call, so I'm just cutting out the middle man!
I have an independent AIS Antenna up my mizzen, not as painful as it sounds but if I wanted to call anyone close enough to help, I would try on my hand held first and if the fan did happen to turn brown, I would set off my PLB.

 

[ShinyShoe]

As I understand it, you follow up a DSC with a voice call, so I'm just cutting out the middle man!

You do, or at least you should. Not 100% clear who the middle man is.
So in a DSC environment on a boat with an AIS Transceiver (no SART) the procedure would be:
Hold red button 5 seconds (*or manually select the distress type etc etc)
DSC message is sent, including MMSI, nature of distress if selected, last known GPS position, time of position.
DSC listens for acknowledgement
VHF re-tunes to CH16 where you follow up with voice, providing the information about the nature of distress, POB, assistance required etc.

But if you don't voice call, provided the CG receive the DSC call you will get a CG response. Initially as a voice call to you.

The digital bit of DSC can travel 50-70 miles from a yacht to a CG aerial, voice 20-30miles is more normal. So it increases your range.

Even if the CG are out of range, almost every other boat that is that far away from a CG aerial will have a DSC set, which will have one of those annoying alarms that goes off when your red button is pressed, and so they can either assist or relay your message.

AIS is not as high powered so your range will be reduced. You will hopefully be noticed by vessels > 300GT who I'm sure if you were out of normal CG range would try to assist in some way even if it is just to establish comms etc. But the yacht that is near by but has turned the volume down on their VHF to avoid hearing the 800 "radio checks" and doesn't have an AIS installed may happily sail past if there is no DSC alert. Added to that the SART function in AIS is relatively recent so some vessels wont handle it in any special way. In fact vessels > 300GT don't have to display the AIS in a helpful way (like on a chart / radar) they comply with SOLAS with old kit that just displays the vessel positions etc.

I have an independent AIS Antenna up my mizzen, not as painful as it sounds but if I wanted to call anyone close enough to help, I would try on my hand held first and if the fan did happen to turn brown, I would set off my PLB.

So, I'm not quite understanding what the AIS SART function is achieving you... When do you think it might be used that the other kit on board might not work for you?

 

[LadyInBed]

I'm not quite understanding what the AIS SART function is achieving you... When do you think it might be used that the other kit on board might not work for you?

Neither am I - yet! I refer you to post #2, I just asked how much and from who, then you turn up extolling the benefits of DSC and castigating me because I choose not to have a DSC VHF fitted! I also refer you to this post: http://www.ybw.com/forums/showthread.php?475559-I-have-a-real-prblem-with-sailing-forums!

 

[RobbieW]

Quick bit of reading suggests that the AIS SART is primarily intended as a locator function for a vessel in distress, much like RADAR SART or EPIRB 121.5 but with added position info. I think it supplements rather than replaces other primary means of indicating distress like DSC/VHF or current EPIRBs.

To the OP, using WiFi doesnt strictly free you from N2K vs 0183 difficulties. It simply wraps the encoded message in a different transmission protocol (hope I'm using the definitions correctly), the receiver still needs to understand the encoding that the message is sent with, ie it cant mix 0183 with N2K messages. WiFi does take away the need for 0183 connections at different speeds when messages are multiplexed.

 

[lw395]

Morning all...

So I just ordered an AIS unit from a German company that does a lot of things in one. Firstly I don't like wiring runs and secondly I feel WiFi capability is futureproof and bypasses N2K to a degree.

So this unit has its own GPS which works fine in the saloon. It has wifi to transmit ais data to an iPad and wifi enabled plotter. It has a splitter to share the VHF antenna or a dedicated one if required. Additionally it has an AIS SART button.

With all that I basically just need to mount it near my DSC and patch them together, sharing the VHF antenna in the masthead. No other wiring needed apart from 12v. I will let you know how I get on with it.

Manufacturer: WeatherDock
Model: A208
Price: £1000 inc vat

View attachment 63483

Seems like a fairly expensive way of putting a single point failure into several erstwhile independent safety related systems.
The GPS which works nicely in the saloon on a sunny day, may not do so in shitty weather with green water on the deck.

 

[ShinyShoe]

Quick bit of reading suggests that the AIS SART is primarily intended as a locator function for a vessel in distress, much like RADAR SART or EPIRB 121.5 but with added position info. I think it supplements rather than replaces other primary means of indicating distress like DSC/VHF or current EPIRBs.

But - and I may be completely missing something - a normal AIS would do that would it not? It would still be providing a position if in distress.

So all I can see it would do is hopefully make the vessel stand out among the clutter of several other boats. But I've heard of old plotters that don't know how to display a SART. I'd assume modern rescue services have plotters that do. But you can't always be certain it will be a rescue service who is going to be first to assist. That's not a problem if it displays something its no worse than a standard AIS.

Provided you've shared your MMSI with whoever is coming to your aid they should be able to see you on their AIS.

So my point remains that I don't feel its a £250 feature.

 

[Tim Good]

Maybe I should restart the thread called AIS with wifi, gps and splitter and see how the focus £££ changes.

 

[ShinyShoe]

Neither am I - yet! I refer you to post #2, I just asked how much and from who, then you turn up extolling the benefits of DSC and castigating me because I choose not to have a DSC VHF fitted!

No I wasn't castigating you for anything. I was challenging anyone on why they'd pay £250 extra for a feature that doesn't seem to do much. But if someone has the money that is obviously their decision, but I was questioning why spend that without having a DSC radio (same or lower cost as the feature) which would seem to do more (in my opinion), seems like a choice of financial priorities that might not be from a fully informed place about how an AIS SART is likely to distress alert versus other methods.

The only reason I am seeing is the DSC alert annoyance.

If you don't want anyone to challenge you on decisions, you'd be better reading a magazine than participating on a discussion forum.

 

[pvb]

Maybe I should restart the thread called AIS with wifi, gps and splitter and see how the focus £££ changes.

Well, I'm not sure the conclusion would be any different. The £750 version can send an AIS SART message, all it needs is the addition of a simple push-button switch (a quid or two). Your £1000 version does exactly the same, except it already has the switch built in. On the plus side, it saves you the effort of connecting two wires to a switch; on the minus side, £250 is a lot to pay for a simple switch! I wouldn't pay £250 extra for that, but then I'm happy to do a bit of simple wiring, maybe you're not.

 

[bitbaltic]

If I wanted an AIS SART and an AIS tranceiver, I'd be buying a battery-powered AIS SART that will go in a grab bag and an AIS tranceiver which bolts to the boat. I see next to no point in combining them even if it saved money (which it is doubtful this does sas said above) becuase an emergency on board with mast up and electrics on doesn't require the use of an AIS SART and you can't use one bolted to the boat in any other circmstances. I think the manufacturers have added the feature because they can, not becuase there's any point in it.