AIS: A Creepy Experience.

[captain58sailin]

I use a transponder type on my vessel, and it does provide useful navigation information. I just don't see them as an alternative to a good radar, it could be viewed as an intermediate step between nada and radar. And the AIS is a very good augment to the radar, it can help you determine the names of the targets on your screen, so that you can make a radio call directly to the vessel you need to and that is a big help. You all would laugh out loud at how many times I have heard "Unknown vessel off my (you pick) port / starboard bow." with no other information given to identify the contact or even the position of the vessel making the call.

[goboatingnow]

Both AIS and radar are fundamentally to aid in collision avoidance. They go about it in different ways, but they're not that far apart when you zoom out a bit

Radar is a multi faceted tool. Its also has uses in collision avoidance, ( arguably more so in modern bridges).

AIS is ONLY a collision avoidance tool, it really does little else.

They are very far apart. Fundementally radar is a detection system, AIS is an anoucement system. ( if it doesnt announce , its not useful). Radar is a first person tool, AIS relies on others.

I shudder when I see people equating AIS with radar, Yes I would put AIS way up the priority list over radar, but thats a argument over price rather then functionality.

Dave

[Kenomac]

Originally Posted by goboatingnow

(edit) "Fundamentally radar is a detection system, AIS is an anoucement system. ( if it doesnt announce , its not useful)."

We only receive AIS and find it useful when combined with our radar that we are trained to use and practiced.

(edit) "I shudder when I see people equating AIS with radar."

Agreed.

(edit) "Yes I would put AIS way up the priority list over radar, but thats a argument over price rather then functionality."

Agreed... Trained and practiced on a good radar is far superior to AIS in that it also tracks vessels which don't send an AIS signal... like us.


Dave

We seem to agree on all but one AIS issue.

[goboatingnow]

Receive AIS is fundamentally not playing fair ( so to speak) it only works if most users DO transmit.

AIS is primarily about transmitting your information, if one does not do that then AIS becomes in essence useless.

RADAR is a detection system and really has no comparison with radar.

rained and practiced on a good radar is far superior to AIS

This is like saying apples are far superior to cumquats. AIS plays a key role in telling other craft what you are and where your going, in that regard it is a very superior tool over radar, which tells other shipping nothing about you.

You have to separate receive only AIS, which is really a technical side road, and almost exclusive to leisure vessels, from the purpose of AIS with is clearly a transceiver system

dave

[Tim R.]

Radar finds nav aids, shorlines, boats. Although I do not completely agree that is not dependent on another party as I have encountered a few boats with no radar reflector and virtually no discernible signature.

AIS only works if a boat is equipped and actively transmitting and you are in range.

Radar has a shadow effect. You cannot identify a boat that is in the radar shadow of a large return(boat, island, etc). Or a boat next to a nav aid can appear as one return. AIS can fill in the blanks here.

Both are generally limited by line of sight. Both are strictly boat-to-boat. Marinetraffic.com and other websites are dependent on Internet based transmitting stations.

A combination of these two technologies is clearly better for limited visibility situations.

[colemj]

Originally Posted by goboatingnow

Receive AIS is fundamentally not playing fair ( so to speak) it only works if most users DO transmit.

Receive AIS was the only game some of us were allowed to play for a long time.

Mark

[goboatingnow]

Receive AIS was the only game some of us were allowed to play for a long time.

Sure sure, In my view receive only should never have been promoted or allowed. But it arrived because classB took so long to get to market. hopefully as prices fall RX only will die away.

Both are generally limited by line of sight. Both are strictly boat-to-boat. Marinetraffic.com and other websites are dependent on Internet based transmitting stations.

TIMR, what do you mean boat-to-boat, AIS is much bigger then boat to boat.( AIS ATONs, virtual ATONS, Satellite AIS, VTS via AIS, shore control of AIS, etc, etc, safety messaging,etc)

dave

[rebel heart]

It's a little dorky but radar is tweaked as well in the case of racon buoys, one of which San Diego has right at the safe water marker.

[Paul Elliott]

Originally Posted by goboatingnow

Sure sure, In my view receive only should never have been promoted or allowed. But it arrived because classB took so long to get to market. hopefully as prices fall RX only will die away.

That's pretty harsh.

I have a transponder because I assume that the ships might want to know where we are. And as you say, if nobody transmitted then the system would be useless.

But, are you suggesting that AIS transponders should be mandatory? How do you feel about radar reflectors or radar detectors? If we all carried reflectors, but nobody had their radar running, then the reflectors and detectors would be useless as well.

I think that receive-only AIS is just fine. The big ships are going to be transmitting AIS regardless. Receive-only lets you see them and call them by name. A transponder is better, but a receiver is still very useful.

[MarkJ]

Originally Posted by Paul Elliott

But, are you suggesting that AIS transponders should be mandatory?


I think that receive-only AIS is just fine.

Yes, I think they should be mandatory for boats going offshore for any reasonable length of time. Aus has some EPIRB laws that could fit... I think its something like more than 2nm offshore.

No, I dont think receive only AIS is fine. I agree with Dave (not often that happens!) that it should have never been allowed.

I think AIS is the greatest safety advance since ECN.

[Bash]

Originally Posted by Wraith_Mac

The NSA is going to love this thread...
boat, bombs, Maine, export, HE.
Those little data mining flags must be pinging about now. LOL

Now that's creepy.

[goboatingnow]

Originally Posted by Paul Elliott

That's pretty harsh.

I have a transponder because I assume that the ships might want to know where we are. And as you say, if nobody transmitted then the system would be useless.

But, are you suggesting that AIS transponders should be mandatory? How do you feel about radar reflectors or radar detectors? If we all carried reflectors, but nobody had their radar running, then the reflectors and detectors would be useless as well.

I think that receive-only AIS is just fine. The big ships are going to be transmitting AIS regardless. Receive-only lets you see them and call them by name. A transponder is better, but a receiver is still very useful.

Well I don't believe its harsh rather more absolute.

Really receive only is a kind of parasite on AIS as a system. Its not even actually part of the IMO spec.

No I wasn't suggesting they be made mandatory. I was saying that the powers that be are mandating them into smaller and smaller vessels. Can't be too long before it arrives at our door.

Radar detectors are a straw man argument. Radar still works with or without it with varying degrees of success.

aIS is a very large integrated system , much larger then we yotties might appreciate. I' m all for its proper implementation.

Dave

[conachair]

Originally Posted by goboatingnow

AIS is ONLY a collision avoidance tool, it really does little else.

In the real world for most people yes, but technically no..

http://www.dft.gov.uk/mca/mcga-mnoti...8E08C2F38A0072


"There is no provision in the Collision Regulations for the use of AIS information therefore decisions should be taken based primarily on visual and/or radar information."

As for everyone transmitting, in the busier areas it can get very cluttered and is nowhere near as useful for knowing what the big boys are up to. Check out the solent on a busy Saturday. Little boats are much easier to dodge.

[Bash]

Originally Posted by goboatingnow

No I wasn't suggesting they be made mandatory. I was saying that the powers that be are mandating them into smaller and smaller vessels. Can't be too long before it arrives at our door.

That's in progress here in the USA. The CG will announce changes in the rules in December. I understand that fishing vessels will no longer be excluded from the requirements, and that the rule will not just apply to vessels venturing offshore or into a VTS area. But for now it appears that they'll keep the 65' rule except for a few exceptions such as towing vessels.

Here's the official scoop: View Rule

Mexico was on the verge of implementing a mandatory AIS rule for all visiting yachts a few years back, but then bailed on the plan when the yachties started screaming they'd go somewhere else.

[Paul Elliott]

Originally Posted by goboatingnow

Radar detectors are a straw man argument. Radar still works with or without it with varying degrees of success.

I don't think it's a straw man. What I was trying to ask was if you think that boats without radar should be discouraged from using radar detectors? Or should radar (and its 24/7 use) be mandatory?

And is there some boat-size cutoff below which an AIS receive-only system becomes acceptable? Day-sailor? Dinghy? Kayak?

Admittedly, I am using reductio ad absurdum, but I do think that receive-only has its place.

By the way, do you think that widespread use of AIS (Class-A or Class-B) will cause all the problems that some have suggested? You know, ships pressing the mythical "ignore" button, etc? My own position is that it's a user-interface issue that will get sorted out.