Do you need AIS?

[Island Time 1,235]

I thought it's time for some more boating topics!

 

AIS;

 

AIS (Automatic Identification System) is a low powered VHF device that shows you, on your plotter (or a dedicated screen) what AIS equipped vessels are near you. It can show considerable details, including;

Vessel name, callsign, MMSI number, Course, Speed, CPA (Closest point of approach), TCPA (Time to CPA), dimensions, and more.

It can have alarms for warning of possible collisions, and can be pretty much set and forget unless the alarms go. False alarms are virtually unheard of.

 

Now a little rant;

 

AIS IS NOT RADAR!!

I have heard recently of some people removing a radar as AIS is "better". Complete nonsense!

AIS is radio communications and plotting with other equipped vessels. It cannot see squalls, coastline, or any other vessel or object that is not equipped with AIS. radar can. 

A radar with MARPA or ARPA can do much of the collision avoidance that an AIS can do, BUT it needs to be monitored and used by a competent person. AIS does not.

Radar has many other functions that an AIS does not - They are completely different!

End Rant

 

 

AIS is currently topical,  people are discussing this now as AIS often comes (as receive only!) on many new VHF radios, and people are considering changing VHF Radios due to the upcoming frequency changes.

 

So, here are my thoughts on AIS to begin with.

 

Many people think they don't need them. SOME are right! MOST people who have a receiver wish after a while that they had got a transponder.

 

So do you need AIS?

 

Firstly, those who sail in daylight, out of the shipping areas, and don't go offshore (or coastal passages with shipping) really, IMO, don't need AIS.

 

For those of us who do venture offshore, especially in the more frequented areas, AIS is simply the best possible warning system to assist with collision avoidance with a large vessel. MOST large vessels now carry AIS.  Not to have one yourself, if you do this type of sailing, is like not using nav lights, because some ships might not have a watch...

 

A receiver is (a lot) better than nothing, but it means that you are still quite likely unseen by shipping, especially in bad weather. If you have to call a ship by VHF to make certain they have seen you or to agree on a crossing, they may not know exactly who they are speaking with, or your exact location.

 

With a transponder, you can see each other. You can see course and speed. It is very rare to have to speak with a ship when you both have AIS. It is simple, clear, and works in any weather.

 

Finally to those who complain about congested screens. Good AIS units allow you to filter targets (unless there is a collision threat), so you can say, for example, only show me targets that will be within X miles of me within X mins etc.  

 

TYPES of AIS - boat units

There are two types of transponder. Class A and Class B. Roughly that equates to Class A for shipping, Class B recreational and smaller commercial vessels (local ferries, fishing boats etc). For most of us, we are class B. Class A uses more power, and has much greater range than Class B. If you have a really fast boat you might like a class A due to it's range. Many class B installs have a reliable range of 10miles or less, but that is plenty for collision avoidance for most yachts.

 

AtoN's

AtoN's are also AIS units - Aids to Navigation. Can be real (physical) or virtual (transmitted from elsewhere) and are used to mark channels, shoals, wrecks etc etc. This is becoming very common, especially virtual ones, as it is cheaper to install and maintain than a physical light/buoy etc. SOME AIS units do not see AtoNs. Make sure yours does - check with the manufacturer. Sometimes you can fix it with updated software, often free.

 

SARTS

Search and Rescue Transponders. AIS SARTS are, IMO, the best MOB device you can have. Better than a PLB, they allow any AIS equipped vessel to see a person/raft/boat in distress in, clearly on the plotter screen. If you have AIS and a crewman so equipped falls overboard, there is no search - simply go directly back to them and pic them up. Again, make sure your primary AIS can detect SARTS, and that the alarm for such an event is VERY loud and unmistakeable. You only have a few miles (4-5) or range, so you need to know immediately if a SART is in your area.

 

Finally, the answer to the initial question - Do YOU need AIS? That answer is NO. But it is sure a great thing to have if you do that type of sailing.

  

[Guest 000]

A great bit of gear and I want one!

What a pity I can't afford it..

[Island Time 1,235]

Pricing is not what it was.

Entry level receivers an be had from about $300 - less if you get one In a VHF. Good transponders from about $900. But you can still spend over $2000 for top of the range with a screen..

 

Yes, it's a cost, but when taken in context of getting a boat to cat1 and the current cost of cruising, it is a pretty small %. 

 

I'm happy to discuss options and cost with anyone who is interested matt@neptunes-gear.com or 0221539176

[Guest 000]

True, but I think my offshore days are over. Now our cruising ground is Tauranga to Bay of Islands so not too much traffic.

My wife is a fantastic sailor - her only fault being that she only has to see a ship as a smudge on the horizon and she starts to get a bit twitchy. The hand bearing compass is never out of her grasp as she constantly reassures herself that the target vessel's bearing is changing and therefore not on a collision course.

AIS would be great for her (and me)

[John B 106]

AIS is super comforting when you see something you know is a ship emerge out of weather but can't immediately tell where its going because its lit up from end to end and no nav lights are visible ( because they're lost in the clutter).

Its on on my wish list.

[Pumbaa 9]

 We're going to do it, I stopped sailing for a living about 20 years ago and apparently that's when my technical knowledge stopped as well. A recent discussion with YNZ on behalf of a customer regarding the Iridium Go, being acceptable for Cat 1, underlined my lack of fluency (ignorance) with the subject. A few years ago I can remember thinking it was all a bit messy and it will settle down, I think that time is here. We'll be doing the AIS vhf, transponder, Iridium Go, tablet/open cpn thing as well as personal AIS transponders for MOB.

 My only concern is the power consumption, with LED's every where and using bluetooth speakers for music and phones/tablets etc for plotters our power needs are tiny. We have a 50W solar panel and a smartish alternator regulator and we don't have power issues (fridge compressor is engine driven). Once we start having equipment running in the background our power needs will escalate and It'll be bigger solar panels and a wind generator. Next thing I'll have an array of stainless scaffolding and a fold up bike hanging off the back of the boat.

[Island Time 1,235]

Power consumption is very small for most units - especially the "black box" type that connect to your existing plotter/PC. For example, the NAIS-400 from B&G averages 170mA! Yep, that is 0.17 Amps, or Approx  4a/hrs per 24 hours. Not much!

 

Pumbaa I'd be happy to talk when you are ready, if you need any help...

[erice 732]

i wonder if the rena

 

have hit astrolabe reef if it had been marked with a solar power AIS tranmitter?

 

are lighthouses etc fitted with them, as well as lights, or are they going to be?

[Island Time 1,235]

Some are now. In fact in the Gulf here in Auckland there are several hazards marked by virtual AIS AtoN's right now.. The ones on the channel markers though, I understand are real.

As time passes we'll see more marks and lights replaced with AIS AtoN's I reckon.

 

Oh and the Rena - wasn't looking at the chart, so probably would not have looked at AIS either!

[Steve Pope 243]

I would expect that any ship responding to a radio call from a yacht would already have them on radar, it would only require them to check at the time of the call to see where the yacht is.

Technically all ships 500 tonnes and over must have AIS, but it can also be turned off, as happened when when Jessica Watson sailed into the side of a bulk carrier off the coast of Australia on her first attempt to sail around the world solo. Shortly after the collission the ship "dissapeared" when they turned their AIS off, they didn't stop.

I think AIS for offshore sailing would be a great stress reliever especially in crowded waters. Apparently it is mandatory in Singapore.

[Island Time 1,235]

Often yachts, even with radar reflectors, are hard to see at more than a mile or two on radar, especially if it is choppy. It needs a radar with the gain etc set just right, and an operator paying attention at the time. AIS does not. I have spoken to several ships that could see us on AIS, but not on radar.....

Yes, units CAN be turned off, but they should not be. That ship was deemed to be at fault, although that matters little if you are dead!

[erice 732]

seem to remember the rena bridge was getting radar returns from the reef

 

but as they couldn't see anything with the binoculars at night

 

didn't bother changing course or checking the charts

 

shows the need to use multiple sources when checking oddities

[marinheiro 352]

just a comment on terminology, the AIS units used in maritime are "Tranceivers". They are transmitting continuously.

A Transponder, as used in aviation, only transmits in response to an incoming signal. Even the Vesper site is incorrect in this respect

Some AIS units can also transmit additional data when "queried", but this is a secondary function.

Re radar reflectors, most are a waste of time and weight aloft, something like this is better option (in addition to an AIS transceiver)

http://www.sea-me.co.uk/

[John B 106]

seem to remember the rena bridge was getting radar returns from the reef

 

but as they couldn't see anything with the binoculars at night

 

didn't bother changing course or checking the charts

 

shows the need to use multiple sources when checking oddities

Vestas got a reading from their depth instruments too. Damn thing broke off though.

[Island Time 1,235]

Yeah, no electronics can help if they are switched off or ignored!!

[rigger 47]

I would expect that any ship responding to a radio call from a yacht would already have them on radar, it would only require them to check at the time of the call to see where the yacht is.

Technically all ships 500 tonnes and over must have AIS, but it can also be turned off, as happened when when Jessica Watson sailed into the side of a bulk carrier off the coast of Australia on her first attempt to sail around the world solo. Shortly after the collission the ship "dissapeared" when they turned their AIS off, they didn't stop.

I think AIS for offshore sailing would be a great stress reliever especially in crowded waters. Apparently it is mandatory in Singapore.

How many people here have radar on their own boat - do you know the hours on the magnetron?

I have found a good number of ships radars are poorly setup with worn out magnetrons - so bugger all picture of value. Then there are the operators that wind the clutter controls up to get a "clean picture" that results in small targets dissappearing.

 

Yes AIS can be turned off, strangely many of the class B units are harder to turn off by the users as they often do not have a display of their own whereas Class A are required to. The class B units are often a box under a console connected to a multifunction display unit - hardwired into the power supply....

 

From Solas:

All ships of 300 gross tonnage and upwards engaged on international voyages and cargo ships of 500 gross tonnage and upwards not engaged on international voyages and passenger ships irrespective of size shall be fitted with an automaticidentification system (AIS)

 

Some are now. In fact in the Gulf here in Auckland there are several hazards marked by virtual AIS AtoN's right now.. The ones on the channel markers though, I understand are real.

As time passes we'll see more marks and lights replaced with AIS AtoN's I reckon.

 

Oh and the Rena - wasn't looking at the chart, so probably would not have looked at AIS either!

BOP Regional council are in the process of setting up a system to create virtual and synthetic AIS AToNs (A Beacon is an example of a real AIS AToN).

Rena had working Radars - if the radar had the AIS data overlayed they might have noticed.

 

The Rangi Channel AIS AToNs are real - at least they were when we recommissioned them a few years back. There were plans to upgrade them but not sure if POAL continued with the plan...

 

 

Just a caution: AIS can have errors - in my job I see position errors greater than 100metres - not huge - but the largest I have seen was over 10nm out of wack, that is significant and rendered the data useless.

[marinheiro 352]

What do people think about the pro's and con's of integrating AIS (and other electronics for that matter) as against stand alone

eg from Vesper's range

standalone: Watchmate 850 and Vision

integrated: XB-8000

The obvious pro for integration is potentially being able to display all info (chart/radar/AIS)on a single screen, the con being if that screen goes down you have nothing.

Other thoughts??

[Beccara 25]

Power draw would be my biggest question, Black box to your plotter will be less power than stand alone screen + plotter however that only matters if you have your plotter on all the time, if you rarely have your plotter on then a separate screen would make sense. Alot of black box's are also doing wifi/ethernet meaning everyone on board can see the data from anywhere not just the helm

[Island Time 1,235]

Power draw is one issue - so is how the alarms are done. It is convenient to have a unit where the alarms still work if the screen is off. A black box unit can do this in some instances - like to a PC with opencpn. The black box and PC must be on, but the screen/s can be off to save power... 

 

As to the radar issue Rigger bought up - it you have a Navico radar (Lowrance/simrad/B&G, 3G 4G or BR24) then there is no magnetron!

 

ALL the vesper AIS models will output AIS data, not just the black box models, so all your capable devices can share.

 

marinheiro, what's your plotter? Sorry I don't remember. If you are using opencpn, you can add wifi for an intranet on your boat for under $50.00, and broadcast all your boat data to mobiles. See this thread http://crew.org.nz/forum/index.php/topic/11972-first-creworg-electronics-and-social-evening/?hl=electronics and the video at the end of it.

 

Happy to answer questions..

Matt

[erice 732]

The obvious pro for integration is potentially being able to display all info (chart/radar/AIS)on a single screen, the con being if that screen goes down you have nothing.

Other thoughts??

 

i have an old raytheon/raymarine plotter that used seatalk to share information between screens

 

ie the plotter could call up the radar display or sounder and the sounder and radar screens could presumably call up the plotter

 

putting all the data on 1 screen and only having 1 screen could be dodgy

 

but modern integrated systems seem to have multiple screens that can share the data so shouldn't be a problem on "cost on object, correctly setup systems"