NASA AIS - any good?

[Thepipdoc]

Are these units any good?

http://www.nasamarine.com/proddetail.php?prod=AIS_radar

Or are there any other AIS recievers that do a similar job?

 

[benjenbav]

I had (probably an earlier model, by NASA) on a previous boat. The issue I found was that I could only set it to North Up which is fine when I was running my chartplotter in the same orientation. But less so if I ran the chartplotter Course Up which I often do for inshore pilotage.

Current AIS is integrated into my chartplotter which I prefer.

Just my view, of course.

 

[Tintin]

I've found this good for the price

http://www.nasamarine.com/proddetail.php?prod=ais_engine

 

[PaulGooch]

Not especially good, what chart plotter do you have ?

 

[Elessar]

Are these units any good?

http://www.nasamarine.com/proddetail.php?prod=AIS_radar

Or are there any other AIS recievers that do a similar job?

does everything I want at a bargain price. Recommended.

 

[Thepipdoc]

Not especially good, what chart plotter do you have ?

I have a Raymarine RC530 plotter on the Flybridge which is the master and a Raymarine RL70C radar on the lower helm (slave).
I'd appreciate any helpful advice you might have.

 

[PaulGooch]

I have a Raymarine RC530 plotter on the Flybridge which is the master and a Raymarine RL70C radar on the lower helm (slave).
I'd appreciate any helpful advice you might have.

The reason i asked, was to see if it was possible for you to use an AIS engine and overlay the AIS data on the plotter. This is a vastly better way of doing things. You can see at a glance where the targets are in relation to your position and the plotter will monitor targets and provide closest point of approach alarms etc.

Unfortunately, it doesn't seem that your plotters support AIS, so unless you fancy a plotter upgrade you don't have many choices. It's either upgrade a plotter (lots of benefits here, but apart from the expense), install software on a laptop and use an AIS engine (not a very elegant solution) or use the NASA unit.

The best solution, IMO, is a new plotter, dual channel receiver (such as a Comar engine) and a second antenna. This might be out of your current budget plans though.

It's important to note :

1) The NASA AIS is not waterproof.
2) You will need a second VHF antenna, don't use a splitter.
3) You will need to be able to supply the unit with an NMEA feed from your GPS.

Two reasons why i said it isn't the best. Firstly, it has limited functionality compared to plotter overlay. Secondly, it's a single channel receiver, as are all NASA AIS engines too. Here's why single channel AIS is inferior, although given your choices you may have to live with it, unless you upgrade a plotter and use a dual channel receiver :


AIS uses channel A and B (not to be confused with Class A and B AIS), these are channels the same as your VHF channels (161.975 MHz and 162.025 MHz). Vessels required to transmit AIS data alternate between the two channels. A single channel receiver, such as the NASA one, will monitor both channels in much the same way your VHF does "dual watch". When there is some data transmitted to channel A, it will switch to channel A, decode the data and pass it to your plotter, all good stuff. The problem is, whilst it was dealing with the incoming data on channel A, any data incoming on channel B will be lost.

Data such as speed, course etc are transmitted every few seconds to every three minutes, depending on how quickly the ships heading etc are changing. Other data, such as the ships name, LOA, draft, etc are only transmitted every 6 minutes, miss this one and you won't get a chance to obtain the ships name for another 6 minutes.

You could technically miss a transmission any number of times. So it is technically possible that a vessel would never be "seen" by your AIS. It's probably very unlikely that this would happen, but you will definitely miss some transmissions, which will reduce the accuracy of your AIS. If a vessel made a single, sudden change of course it would transmit that data within seconds, if not immediately. If you missed the transmission and the vessel then held it's course and speed it wouldn't be transmitted again for another three minutes, hopefully you don't miss this one.

The busier the area, the more transmissions, the more likely you are to miss data.

 

[PCUK]

As it's not a very important item - we managed for years with them, the Nasa engine is good. It doers what it needs to do and nothing else. I have one on my Raymarine C60. Excellent value for money unit.

 

[PCUK]

As it's not a very important item - we managed for years without them, the Nasa engine is good. It doers what it needs to do and nothing else. I have one on my Raymarine C60. Excellent value for money unit.

 

[bluejasper2]

got nasa ais engine on laptop gps next to lower helm picks up all ships transmitting no problem .

 

[PaulGooch]

got nasa ais engine on laptop gps next to lower helm picks up all ships transmitting no problem .

How do you know this ? Do you have another, dual channel receiver sitting beside it to compare the accuracy and speed of data acquisition ?

 

[PaulGooch]

As it's not a very important item - we managed for years without them, the Nasa engine is good. It doers what it needs to do and nothing else. I have one on my Raymarine C60. Excellent value for money unit.

got nasa ais engine on laptop gps next to lower helm picks up all ships transmitting no problem .

I'm not saying it doesn't work. But, like it or not, it will only work how i described it in post #7.

However much a bargain it was, it's still a single channel receiver.

 

[bluejasper2]

no other contacts on radar

 

[Alfie168]

I'm not saying it doesn't work. But, like it or not, it will only work how i described it in post #7.

However much a bargain it was, it's still a single channel receiver.

Nasa's AIS Engine Series 3 (blue label) is a two channel receiver for £110 plus the dreaded VAT. It alternates between A & B.

Tim

 

[PaulGooch]

Nasa's AIS Engine Series 3 (blue label) is a two channel receiver for £110 plus the dreaded VAT. It alternates between A & B.

Tim

It's a single channel receiver.

It only receives on one channel at a time.

Exactly as i described.

A full and proper dual channel receiver will monitor both channels and can simultaneously receive data on both channels.

The NASA monitors both, but can only receive on one channel at a time. While it's receiving on one channel, it's oblivious to anything being broadcast on the other.

NASA have a habit of using misleading descriptions. Such as "dual channel" and "radar". This is neither.

 

[bluejasper2]

radar was on diferent plotter not nasa

 

[Alfie168]

I'm sure you are right, but for most folk it will provide all the info they need..on a single channel which alternates between Class A and Class B signals.

Tim

 

[PaulGooch]

I'm sure you are right, but for most folk it will provide all the info they need..on a single channel which alternates between Class A and Class B signals.

Tim

You still haven't got how it works, may i suggest you read what i posted earlier.

It does NOT alternate between class A and B signals. It alternates between the two available broadcast frequencies....... i already typed this up once, go back and read it.

 

[PaulGooch]

radar was on diferent plotter not nasa

No, i was referring to the fact that NASA incorrectly marketed the AIS with screen as "AIS radar".

 

[Philiz]

I have the NASA unit. It does work how Paul Gooch describes, so may be a bit limited compared to other (possibly more expensive) units. But I find it good enough for the areas we frequent.