AIS, Receiver or Transmitter

[Mike OReilly]

I've seen a few folk here equating AIS to RADAR. They are as similar as a chartplotter is to a depth sounder and compass. One gives you a facsimile of reality while the other is a real-time measure of what is actually out there. While their function can overlap, they are not the same thing.

If you really had to choose between AIS and RADAR (and it's hard to see why you would), the choice should be a no-brainer.

[Sandero]

Originally Posted by Mike OReilly

I've seen a few folk here equating AIS to RADAR. They are as similar as a chartplotter is to a depth sounder and compass. One gives you a facsimile of reality while the other is a real-time measure of what is actually out there. While their function can overlap, they are not the same thing.

If you really had to choose between AIS and RADAR (and it's hard to see why you would), the choice should be a no-brainer.

Silly comment Mike... Both show things in the environment on a chart plotter. Radar shows echos.. AIS shows stations which send out information. Both systems are "incomplete" for any number of reasons. Each system adds safety when properly used and understood.

AIS would not do much in the middle of the ocean with no ships... but Radar could show approaching rain squalls and so forth.

Both may give a false sense of complete environmental awareness. But more data is better than less.

It may be assumed that all ships have someone standing watch... but what about looking at a radar or an AIS plotter? And how many silence alarms which repeatedly go off and drive you nuts?

Pay attention!

[cal40john]

I bought one. So far I haven't installed it, just tested it. I already have a netbook with seaclear on it and a gps plugged into it. The dAISy can be USB powered by the netbook. I grabbed a spare 2 meter antenna ($10 metal rod on a pl259) to attach to it and propped it up in a corner of the cabin. Worked fine on the test. If you have any display already, your complete install can be under $100.

Originally Posted by anacapaisland42

Has anyone heard of:
dAISy Open Source AIS Receiver
I haven't seen anything posted about this so I thought I would.

A fellow named Adrian Studer has designed an open source AIS receiver and is selling them at a pretty low cost ($55). You can find them here on Tindie (recently back in stock)
https://www.tindie.com/products/astu...-ais-receiver/

Or you could find the sources and board layouts on github and build one yourself.

Here is an article of a boater using one with OpenCPN on linux (Raspberry Pi).
https://mvcesc.wordpress.com/2015/04...pi-2-with-ais/

Originally Posted by El Pinguino

RX/TX really is a no brainer...

Lots of interesting 'costs' being thrown around here but this is what the Milltech website ( v good people to deal with) AIS Receivers has on offer.

Cheapest RX is the Amec Cypho 150 at $199, Cheapest RX/TX is the Amec Camino 108 at $489.... $290 diff.
Assuming you already have a display to hook it up to the only other cost ( which is common to both ) is about $100 for a VHF antenna and a length of co-ax. Forget the splitter, forget sticking it up the mast... just stick it on the taffrail. Job done.

Cheapest VHF/AIS combo they list is the Lowrance at $289.

[havnjero]

Originally Posted by Vortec

If everyone had a receive-only... It is mandatory for most boats to have TX/TR.

From Wikipedia: The International Maritime Organization's International Convention for the Safety of Life at Sea requires AIS to be fitted aboard international voyaging ships with gross tonnage (GT) of 300 or more, and all passenger ships regardless of size.

as you've kindly pointed out AIS (tx/rx) is mandatory on most commercial vessels only. for recreational (class b) vessels it remains to be only a strongly endorsed idea.

I'm with Jim (hi guys!) and have a Vesper XB-8000 and I don't notice its current draw and it is constantly on. (I turn off transmit when I'm docked at a marina).
oh, it's also an nmea multiplexer...

/Miles

[Don C L]

Wow, I never would have guessed this thread would have generated this much debate.

[alaskaflyfish]

Originally Posted by DotDun

As stated previously, the value of AIS, IMO, is no/low visibility and/or high traffic areas. As I stated, I don't even transmit AIS unless one of those conditions are present. If one never encounters either, the value of AIS goes way down. If you never transit in traffic, dark, or storms, you can probably get by without AIS or radar.



Let's go back to post #68:
http://www.cruisersforum.com/forums/...ml#post2203059

As I stated in the post (shown below), it's not arrogant to buy a receive-only AIS, but IMO, it's arrogant to state: "I need AIS to see you, but you don't need to see me via AIS as I alone am capable of avoiding a collision with you". That is claiming one never makes mistakes, that is arrogance. And yes, I still believe receive-only AIS devices are half-assed.

I think you may be confusing "arrogance" with "competence". Nothing was alluded that people are faultless and without mistakes.

[bobmcd625]

Thanks for the tips on Vesper transceivers. I won't need a display since I am installing a B&G Vulcan display which relies on a NM2K network. Also have external GPS antenna, but it looks like Vesper wants its own, not one on the network. Maybe redundancy is good. Could get Vesper 6000 with separate VHF antenna although splitter may be more practical even if not cheaper. Could skip AIS in Radio to save a few $. Nothing is perfect!
Interesting discussion, but I'll just watch!
Fair winds.
Bob

[JPA Cate]

Originally Posted by TJ D

Ann, I'm not clear how transmitting changes your situation while on watch?

Transmitting happens in the background, and the information that you see is only derived from the receive function anyway, so the act of transmitting should not change anything.

Did you put in a new unit with a different display? This would seem to be about the only thing that could have happened. Transmitting shouldn't matter a bit.

TJ

Hi, TJ,

Yes, it was a new unit and in a different location. I found the display distracting, at night, and also too bright for me to retain my night vision. Our boat does not have a chartplotter in the cockpit, either, and I much prefer to come below to check it, when I can plan to keep one eye closed, to retain night vision.

With the RX only, it was mounted below, where by effort could be seen from the cockpit, and it dimmed more completely.

There is also a subtle seduction that I have to fight, I have to remember not everybody out here has AIS--there's always going to be ill lit or non-lit vessels that are poor radar targets that I need to be vigilant for--again, more so at night, because in some conditions, all you see is a darker shadow against the black of the night sky. Unlit timber fishing boats really get my goat!

Ann

[capngeo]

You guys are making me feel rather impotent; my primary collision avoidance system is a set of Mk1 eyeballs. I do have VHF (rarely turn it on), and I have a compass! My depth finder (yes I said depth finder) gives me two digits to work with. My plotter is my iPhone, but again rarely used in favor of paper charts, a bearing compass, and above mentioned Mk1 eyeballs.

The above notwithstanding, I have a small (28') boat and rarely get more than 60nm offshore on a passage.... AND try my damnedest to make my passages in daylight

[Don C L]

Originally Posted by capngeo

You guys are making me feel rather impotent; my primary collision avoidance system is a set of Mk1 eyeballs. I do have VHF (rarely turn it on), and I have a compass! My depth finder (yes I said depth finder) gives me two digits to work with. My plotter is my iPhone, but again rarely used in favor of paper charts, a bearing compass, and above mentioned Mk1 eyeballs.

The above notwithstanding, I have a small (28') boat and rarely get more than 60nm offshore on a passage.... AND try my damnedest to make my passages in daylight

Heavens! And you survive?
right there with ya, Cap'n! 'cept I rarely use the re-tasked fishfinder.

[El Pinguino]

Originally Posted by DotDun

As stated previously, the value of AIS, IMO, is no/low visibility and/or high traffic areas. As I stated, I don't even transmit AIS unless one of those conditions are present. If one never encounters either, the value of AIS goes way down. If you never transit in traffic, dark, or storms, you can probably get by without AIS or radar.......

**Edited to remove a bit ... memo to self.... read the previous post properly.**

IMNSHO AIS is of greatest value when offshore in places less frequently travelled... where you aren't expecting to see any ships and the ships aren't expecting to see you.

I try and avoid fog although now and again I find myself dealing with poor vis.

As a result my radar rarely goes on.... in over 15 years I think it has about 200 hours on the magnetron.

In clear vis and traffic I would only refer to the AIS now and again.

[Mike OReilly]

Originally Posted by Sandero

Silly comment Mike... Both show things in the environment on a chart plotter. Radar shows echos.. AIS shows stations which send out information. Both systems are "incomplete" for any number of reasons. Each system adds safety when properly used and understood.

AIS would not do much in the middle of the ocean with no ships... but Radar could show approaching rain squalls and so forth.

Both may give a false sense of complete environmental awareness. But more data is better than less.

It may be assumed that all ships have someone standing watch... but what about looking at a radar or an AIS plotter? And how many silence alarms which repeatedly go off and drive you nuts?

Pay attention!

Only you can decide if my comments are silly. Doesn't change what I said: they are not the same thing. RADAR shows echoes. AIS shows location of external transmissions. You are in control of your RADAR. You have no control over the AIS transmission. You have no idea who is NOT transmitting, or is transmitting erroneously. RADAR is sampling the environment in real time, to the limits of the system and the operator. It is not dependent on someone else transmitting, or not. Same with sonar.

A chartplotter is, at best, an approximation of a location. It is based on charts which may, or may not, be an accurate portrayal of the environs. And it is based on a GPS fix, which can be many tens of meters off in good fixes. In poor fixes the error can increase significantly.

Both AIS and RADAR (and chartplotters) provide an incomplete picture. This is stating the obvious. Eyeballs show an incomplete picture. That is a silly statement. All I said is that AIS and RADAR are not the same thing, and should not be substituted for each other.

BTW, more data is not always better. It's a well studied psychological phenomena. At some point more data leads to poorer choices, not better. But that's a different discussion. In this context I'm not suggesting one shouldn't have AIS, or not have RADAR. Have both if you can. I'm just saying they are not the same thing.

[skipmac]

Originally Posted by bmz

This is a plea for those of you who haven't already purchased one, not to purchase an AIS transceiver (unless the transmitter can be independently turned off from the receiver, in which case it is a plea for that).
I am not the kind of guy who buys the maximum amount of insurance, regardless of cost; I do not buy the most expensive brand because it might be better; I do not buy the next size up because it might be stronger, etc.. Yes, bang for the buck is important to me. I sail an Irwin 34 that I purchased new 34 years ago for $54,000. My AIS receiver cost me $200 plus $40 for a separate antenna. I simply would not have spent 700+ dollars for an AIS transceiver.
I am not particularly concerned about a collision with another small boat, we are both maneuverable, can easily see each other, we can hear each other's horns, sailboats travel slowly, and fast powerboats are noisy. Over the last 34 years I have been irritated by some ******** who have failed to yield (including myself), but a horn and an appropriate steering correction is all that has been necessary (also I have never been foolish enough to anchor in sealane).
I sail the Chesapeake near Baltimore, and what I really do fear (especially at night) are the large freighters and tugs pushing large barges. They are the stand on vessels because they cannot maneuver. My crew and I have often discussed what those huge moving masses without lights out on the bay were: secret military cargo, double barges, parallax, etc.; regardless, we have seen them. Near Baltimore harbor they can appear almost out of nowhere. My AIS receiver has been a godsend--and produces the most bang for the buck of any piece of gear I have. I usually solo sail; and it is wonderful not to have to worry anymore. No matter how busy I am, no matter how inattentive, no matter what, my AIS protects me.
The only issue I have with it is all you other guys out there with your AIS transmitters on--you so clutter up my screen--you produce so much unnecessary audible alarms. I don't want to see or hear you on my chart plotter screen; we will be able to see each other just fine when you get closer; the only danger you are to me is interfering with what I consider the appropriate use of my AIS receiver. It is no skin off my nose if you buy too much insurance, have too big an anchor or anchor chain or spend too much money making yourself feel totally secure; unless, you have an AIS transmitter on. Then I consider you to be a pain in the ass.

Secret barges and freighters running the Chesapeake at night with no lights and yet they transmit an AIS signal? If they are secret and mysterious and trying to hide why would they transmit an AIS signal?

[JPA Cate]

This is not a pro/con statement, really just a comment.

Sometimes even ships who are supposed to be transmitting, aren't. In the case I have in mind, VHF traffic revealed that it's AIS had malfunctioned, and they needed to fix it while in port.

The posters who say the mark one eyeball is primary do have a point. Also, where and how you sail does have a bearing on whether you "should" have AIS.

Mark J's screen pic shows how his having transmission made it easier for ships to avoid him, it is the beauty of having the TX function.

I agree with Mike OReilly about the receive being adequate unless you frequent busy sea lanes frequently. The ships generally go about their business.

This gets to people evaluating their own needs, and desires and telling the difference between the two. To disparage and denigrate someone because he or she chooses something different from what you would choose for yourself, that's purely bad manners, and rather unbecoming.

Ann

[roland stockham]

Fitted a transceiver before my last ocean passage and am now sold, it is on my must have list. I was amazed to watch commercial ships altering course 10-15 miles out by a few degrees to gain the ideal clearance. Biggest advantage is that you see the course change so no more "are they clearing or not? Have they seen me or not?"
I also imagine big ships love them because they can see you reliably and see your course, speed and heading. All those things are quite difficult to get from radar when you have a week intermittent signal from a small boat hidden in the wave clutter and with (relative to a ship) poor course holding.