AIS Pros & Cons?

[Fletcher500]

In the PNW, the large ships turn off Class B targets and rely solely on Radar. It is the opinion of the Puget Sound Pilots Association that AIS for Class B is a distraction as it does not tell the Pilot where the boat is, onlY where it was. Personally, I find AIS very helpful when maneuvering with large commercial traffic.

I am a bit surprised to hear ships turning off Class B (recreational) targets up there. I spend a fair amount of time going through the shipping channel down here, and have been hailed by vessel name by both foreign and domestic ships. I asked my buddy today, a 30 year LB Pilot and he also confirmed they keep all targets active on AIS: A and B.

As 95 percent of the people on here have already stated, AIS is a no brainer. All upside.

 

[guy with a boat]

Again, seemingly oblivious to the same boating world I know…

There is no need to argue it further..... you nor anyone else has shown me anthing I don't already know about AIS. I have stated my view about as well as I can if people stop and really think of all the situations it might help versis those where it won't at all.

When is the last time you actually used AIS? Have you run a boat with AIS in the past 5-10 years? i’m having a hard time understanding your impression that it is only a “fractional” improvement. Thats not my experience at all. Fractional as in less than 100%, sure. Fractional as in suggesting an insufficient number to be very useful, I disagree.

Your experience over the decades past may be a less reliable indicator when evaluating a relatively recent tool, and one which continues to grow in acceptance and usage.

 

[psneeld]

When is the last time you actually used AIS? Have you run a boat with AIS in the past 5-10 years? i’m having a hard time understanding your impression that it is only a “fractional” improvement. Thats not my experience at all. Fractional as in less than 100%, sure. Fractional as in suggesting an insufficient number to be very useful, I disagree.

Your experience over the decades past may be a less reliable indicator when evaluating a relatively recent tool, and one which continues to grow in acceptance and usage.

My boat had VHF with AIS receive. Sold it a little less than 2 years ago. Rarely looked at it....on my chart plotter it generally was just ignored.

Have still been o n the water around Ft Piece, Fl inlet and still see that 80+ percent of the targets in that inlet are probably not carrying AIS due to size and type boaters. That based on my street alone the couple boaters I know don't even know what AIS is.

I an just a bit different than some in the discussion here. I pretty much only use Radar in low vis. I pretty much only use the VHF when I absolutely have to. I don't use a lot of Nav equipment like some think it'sa necessary safety device like the compass.

One last time...... AIS is a tool. It will not keep you from running into a large number of coastal US objects. If it makes your life easier and better have at it. Say it is the greatest boating tool of all time. But spare me that it should be mandated, maybe it should. But first a lot of other things like training and experience should be too...and way beyond the safety certificate. To say that it is equal in "safety" to its 'usefulness" to me is just wrong as those can be 2 distinctly separate things. So while not opposed to AIS, just hoping people that don't have it realize what it really is and isn't with every day professional crews both commercial and pleasure having mishaps despite AIS one thing part of their nav suite.

Till boats are fully automated, the skipper is still the weak link no matter what gear is on board.

 

[CaptTom]

Yes, AIS is a tool. There is no "con" to having another tool at your disposal.

I agree we're not at the point where mandating AIS for all would make sense. I agree there are too many uneducated and uncaring operators out there. But those are not the topic of this thread.

 

[rwidman]

In the PNW, the large ships turn off Class B targets and rely solely on Radar. It is the opinion of the Puget Sound Pilots Association that AIS for Class B is a distraction as it does not tell the Pilot where the boat is, onlY where it was. Personally, I find AIS very helpful when maneuvering with large commercial traffic.

I would like to see your claim documented.

Radar doesn't display the name of a vessel, AIS does.

I have been in a few situations where a commercial vessel called my boat by name (on the VHF) and asked me to alter course or at least discussed passing arrangements. I find this works much better than just calling "beige trawler near [some landmark]".

Class B AIS transmits a boat's position within the last minute or so. A boat would have to be travelling very fast for any inaccuracy.

 

[psneeld]

Yes, AIS is a tool. There is no "con" to having another tool at your disposal.

I agree we're not at the point where mandating AIS for all would make sense. I agree there are too many uneducated and uncaring operators out there. But those are not the topic of this thread.

If you dont believe the vast majority of US coastal small boats are pertinent and part of the discussion, then no wonder the emphasis on it being a wonder tool

 

[psneeld]

I would like to see your claim documented.

Radar doesn't display the name of a vessel, AIS does.

I have been in a few situations where a commercial vessel called my boat by name (on the VHF) and asked me to alter course or at least discussed passing arrangements. I find this works much better than just calling "beige trawler near [some landmark]".

Class B AIS transmits a boat's position within the last minute or so. A boat would have to be travelling very fast for any inaccuracy.

You obviously have my posts blocked or the one descibing closure rate got by you. I did the math, how about you? Plus experience and other postesrs have described it's flaw.

 

[Davil1]

interesting

Class B ships send position reports every 30 seconds when traveling faster than 2 knots; otherwise, it drops back to every 3 minutes. Information that doesn't frequently change, such as the vessel's name, size, and voyage information, is sent every 6 minutes for Class A and B.
====================================
What is the transmission rate for Class A AIS?
Class A ships send position updates every 2 - 10 seconds depending on their speed and rate of turn, or every 3 minutes when reporting as anchored or moored and not moving faster than 3 knots.

 

[rslifkin]

Class B+ is similar to class B, but once you reach 14 kts it transmits every 15 seconds. And at 23 kts it steps up to every 5 seconds.

I did the math. For a typical fast and slow cruise on my boat with class B+, we'd move about 430 feet between updates at fast cruise (15 seconds at 17 kts) and about 340 feet between updates at slow cruise (30 seconds at 6.7 kts).

 

[Davil1]

Ais

I have my Vesper in the cabin, and have WatchMate app installed in every tablet and cell phone for convenience when at the helm in the cockpit.

When the alarm goes off, can check my tablet without going downstairs, or when visually looking out (Colreg 5) to confirm.

I noticed there is a discrepancy on the positions of targets, not sure how to explain it.

For instance, a target crossing my bow on the transponder screen shows having crossed it? on a tablet.

 

[SteveK]

Class B+ is similar to class B, but once you reach 14 kts it transmits every 15 seconds. And at 23 kts it steps up to every 5 seconds.

I did the math. For a typical fast and slow cruise on my boat with class B+, we'd move about 430 feet between updates at fast cruise (15 seconds at 17 kts) and about 340 feet between updates at slow cruise (30 seconds at 6.7 kts).

You said you did the math so I will take your post as accurate.
Suppose two boats are on a collison course and the collison is 340 feet from their reported positions. The collison occurred just as their last position is updated.
When does the collision alarm sound off?

 

[Davil1]

https://shop.vespermarine.com/vision/guide/settings-alarm

 

[rslifkin]

You said you did the math so I will take your post as accurate.
Suppose two boats are on a collison course and the collison is 340 feet from their reported positions. The collison occurred just as their last position is updated.
When does the collision alarm sound off?

It depends on how you configure the alarm, but if used reasonably, it would have alarmed well before the collision. Typically you can set it to alarm for (or visually mark) any vessel where the available info indicates you will get within X distance within Y time. So in open water you may want it to tell you about any vessel that looks like it'll get within a 1/2 mile within the next 15 minutes, for example.

 

[mvweebles]

......
When does the collision alarm sound off?

5 minutes prior. At least.

Peter.

 

[SteveK]

Class B+ is similar to class B, but once you reach 14 kts it transmits every 15 seconds. And at 23 kts it steps up to every 5 seconds.

I did the math. For a typical fast and slow cruise on my boat with class B+, we'd move about 430 feet between updates at fast cruise (15 seconds at 17 kts) and about 340 feet between updates at slow cruise (30 seconds at 6.7 kts).

Originally Posted by SteveK
You said you did the math so I will take your post as accurate.
Suppose two boats are on a collison course and the collison is 340 feet from their reported positions. The collison occurred just as their last position is updated.
When does the collision alarm sound off?

It depends on how you configure the alarm, but if used reasonably, it would have alarmed well before the collision. Typically you can set it to alarm for (or visually mark) any vessel where the available info indicates you will get within X distance within Y time. So in open water you may want it to tell you about any vessel that looks like it'll get within a 1/2 mile within the next 15 minutes, for example.

Bear with me.
60 seconds ago you were not on a collision course, and were as much as 1360 feet apart or about 1/4 mile. One or both boats change course between the 30 & 60 second positions and now you are on a collision course. But neither AIS is yet reporting this due to last positions & course.

What I see is the collision occurred before the AIS alarm went off. The two boats were on a collision course after the 60 second position mark but before the 30 second mark would realize a collison course pending.

This also explains where my onetime use of AIS was showing boats where they were, not where I see them.
I hope I missed something because this cancels out AIS is a safety device that so many think it is.

 

[Davil1]

https://shop.vespermarine.com/vision/guide/settings-alarm

=================================
I posted the link from Vesper imagine all AIS have the same programming?

gives all the adjustments needed

===========================================
============================================
Each Alarm Profile has three settings associated with it. Select Profile Alarms form the Alarms Menu to adjust these settings.

Guard Alarm is used to set a range around your vessel. Whenever a target penetrates your range setting, an alarm is triggered.

Collision Alarm is triggered when a target meets your alarm criteria.
Collision Warning causes a target to be displayed in a warning state when it meets this criteria.


When adjusting the alarm and warning settings there are three controls which work together to determine the criteria. For a target to meet the alarm or warning criteria it must meet each of the settings.

CPA is the closest point of approach. It is the distance that the target will come to your vessel if both continue on their same course and speed. If you want an alarm for any target that will come within a half mile of you at some point in the future, then set this value to 0.5nm.

TCPA is the time of CPA. It is the number of minutes before the target will reach its closest point to your vessel. Use this setting to suppress alarms unless the CPA will be soon. For example, if you set this to 10 minutes it means that you will get an alarm when a target is going to come closer than your specified CPA within the next 10 minutes.

Target speed allows you to suppress alarms for slow moving, or stationary targets. This is very helpful when
operating in a harbor where there are many moored or
anchored vessels.

 

[SteveK]

5 minutes prior. At least.

Peter.

Both boats would have to be on recorded collision course for more than 5 minutes ago. Then you have time to alter course.

 

[rslifkin]

Bear with me.
60 seconds ago you were not on a collision course, and were as much as 1360 feet apart or about 1/4 mile. One or both boats change course between the 30 & 60 second positions and now you are on a collision course. But neither AIS is yet reporting this due to last positions & course.

What I see is the collision occurred before the AIS alarm went off. The two boats were on a collision course after the 60 second position mark but before the 30 second mark would realize a collison course pending.

This also explains where my onetime use of AIS was showing boats where they were, not where I see them.
I hope I missed something because this cancels out AIS is a safety device that so many think it is.

The alarm isn't a collision alarm. It's a "closest point of approach" alarm. So if you had the alarm set to a 1/2 mile (because you're not in a confined area and have no reason to be close to other boats), it would have alarmed long before you were 1/4 mile apart (because it would have seen that you'd get within a 1/2 mile, even if you weren't on a colission course).

 

[SteveK]

The alarm isn't a collision alarm. It's a "closest point of approach" alarm. So if you had the alarm set to a 1/2 mile (because you're not in a confined area and have no reason to be close to other boats), it would have alarmed long before you were 1/4 mile apart (because it would have seen that you'd get within a 1/2 mile, even if you weren't on a colission course).

OK, a proximity alarm letting you know another boat has entered your geofence.

 

[rslifkin]

OK, a proximity alarm letting you know another boat has entered your geofence.

Not just that it has, but that based on each boat's current course and speed, that it will get within that distance in the time window you set. So it can mark boats on the screen as "safe" (won't get near you) or "dangerous" (will get within X distance in the next Y time). You can have it alarm for the dangerous boats or just show them visually. Basically those are the boats you need to be aware of, and the ones marked "safe" won't get close enough to care, so you can ignore them.

 

[mvweebles]

OK, a proximity alarm letting you know another boat has entered your geofence.

My point was the only way your scenario could happen is the operator removed all the other settings. Mind you, on your scenario, both boats have at least receive Class B which has a range of 5 miles or so. One or both boats would have to do a last minute "Crazy Ivan" turn right towards one another. Meaning they suddenly became a collision target.

AIS is working fine, but is not the right tool for a last minute extreme even. Frankly, Radar would be a bit better but still not great. No time for MARPA to aquire and track.

Personally. I view AIS as extremely useful where there is commercial traffic. Ships and ferries especially can be hard to track and detect speed. For recreational vessel tracking in hi-population areas (vs coastal), less practical use and more novelty and speciality use. Of course, being able to hail a boat by name to establish passing or overtaking agreement is very helpful, well past novelty usage.

Peter

 

[rslifkin]

Yup, both AIS and ARPA/MARPA will frequently determine if a boat is going to get close enough to be a concern before you can accurately determine that visually. AIS giving you the name of a boat can be handy as well, even if you already had adequate information for collision avoidance, etc. from other means.

 

[SteveK]

Not just that it has, but that based on each boat's current course and speed, that it will get within that distance in the time window you set. So it can mark boats on the screen as "safe" (won't get near you) or "dangerous" (will get within X distance in the next Y time). You can have it alarm for the dangerous boats or just show them visually. Basically those are the boats you need to be aware of, and the ones marked "safe" won't get close enough to care, so you can ignore them.

OK, I was going to leave it. But look at my previous post. That safe boat changes course between last position, speed and course is next reported. Sorry, but AIS in close promimity may not tell you in time of a collison pending.
Please use your eyes.

 

[rslifkin]

OK, I was going to leave it. But look at my previous post. That safe boat changes course between last position, speed and course is next reported. Sorry, but AIS in close promimity may not tell you in time of a collison pending.
Please use your eyes.

Obviously you still use your eyes and anything else available to give you information. But my point was that if you have the AIS alarms set up reasonably, you won't collide with a target marked "safe". If they're not going to get within a half mile of you on their current course, they'd have to be going damn fast with an old class B unit (30 second updates at any speed) to change course and hit you before the AIS noticed the course change and warned you. And by damn fast, I mean they'd have to be doing 60 kts to cover a 1/2 mile in 30 seconds. So in most cases, they'd already be marked "dangerous" and you'd know they're one of the boats around you to keep a close eye on (via all available methods including visually).

 

[psneeld]

OK, I was going to leave it. But look at my previous post. That safe boat changes course between last position, speed and course is next reported. Sorry, but AIS in close promimity may not tell you in time of a collison pending.
Please use your eyes.

I think most do use their eyes , other electronics, and other skills.

Some use all those things. ...some only use some or even one. Considering how many without AIS avoid collisions and how many with it have collisios......hmmmm.....love to see that breakdown.

 

[mvweebles]

OK, I was going to leave it. But look at my previous post. That safe boat changes course between last position, speed and course is next reported. Sorry, but AIS in close promimity may not tell you in time of a collison pending.

Please use your eyes.

I don't think anyone said AIS supplants all else. These threads tend to be dominated by fairly experienced boaters who often cite that newer boaters fixate on electronics. Over time, you have to learn to scan your instruments to augment visual watch keeping. If conditions are poor and visual watch keeping is compromised, speed and proximity need to be adjusted to buy time.

There are exceptions to all rules. AIS is a fantastic tool but there are some situations where it's a better tool than others. In the end, you gotta trust your lyin' eyes.

 

[psneeld]

I don't think anyone said AIS supplants all else. These threads tend to be dominated by fairly experienced boaters who often cite that newer boaters fixate on electronics. Over time, you have to learn to scan your instruments to augment visual watch keeping. If conditions are poor and visual watch keeping is compromised, speed and proximity need to be adjusted to buy time.

There are exceptions to all rules. AIS is a fantastic tool but there are some situations where it's a better tool than others. In the end, you gotta trust your lyin' eyes.

And thus my rub... I taught many experienced boaters that never developed a scan or situational awareness.

They just don't boat enough and become complacent in their own backyard waters.

They would be told to hold a course several miles off shore and they would alway veer shareware from the you go where you look phenomenon.

They would miss slowing down in a no wake zone because they were concentrating on depth and engine instruments.

They would almost run over boaters in the ICW because they were fixated on ATON and what the chartplotter was showing.

The classic learning moment is when students go from behind the machine to in front of it. Pilots get there fast or die young. Fortunately this part of boating isn't all that lethal.

Scan? What scan for most..... even in cars at 60 many are distracted drivers....so much so the laws and barrage of ads signal the lack of "scan" by the average vehicle operator.

 

[Simi 60]

.

I can only remember once being in heavy rain and losing Radar picture, I think it was that day that I got much better at tuning it. Sure wou wont pick up all targets, but most and certainly the good ones.

I agree

But I have lost GPS before in insanely heavy rain with hail and high winds so for some AIS and nav that use GPS only that could be an issue.
In that same weather event radar still worked.

Our AIS and nav now uses $10 pucks that use BeiDou, Glonass, Galileo and GPS satellites
Never had a dropout since

 

[mvweebles]

And thus my rub... I taught many experienced boaters that never developed a scan or situational awareness.

They just don't boat enough and become complacent in their own backyard waters.

They would be told to hold a course several miles off shore and they would alway veer shareware from the you go where you look phenomenon.

They would miss slowing down in a no wake zone because they were concentrating on depth and engine instruments.

They would almost run over boaters in the ICW because they were fixated on ATON and what the chartplotter was showing.

The classic learning moment is when students go from behind the machine to in front of it. Pilots get there fast or die young. Fortunately this part of boating isn't all that lethal.

Scan? What scan for most..... even in cars at 60 many are distracted drivers....so much so the laws and barrage of ads signal the lack of "scan" by the average vehicle operator.

I remember bringing a Nordhavn 47 from Dana Point to Portland OR with the owners aboard. Younger couple (40-ish?) From San Francisco, tech sector types.

Heading up the Columbia were going past a big oxbow in the river. To port is a steep hillside, probably 75 feet up. To port is the low sand island forming the oxbow. The owner starts veering towards the sand island. I tell him to head to port - there's deep water there where the cliffs are. He said now, the chartplotter says there's deeper water to starboard. I tell him to look astern at the mud wash. A turn to port and we were back in relatively deep water.

It takes time to develop a rhythm of ingesting information. A recently had a conversation with the wife of a cruising couple. She had awaken her husband in the middle of the night for some reason and she felt a bit guilty. I told her of an experience with me and my wife. Middle of the night and we were passing the approach to Long Beach CA where ships hold station before entering the harbor. My wife yells down to get me up ASAP. frankly. She waited 5 minutes too long. I was a bit disoriented and took me a bit to get my bearings and figure out the Ouija board in front of me.

I guess it's all part of why I enjoy boating. A lot of relaxation, but also some challenges. And I constantly learn and improve.

Peter

 

[ranger58sb]

Sorry, but AIS in close promimity may not tell you in time of a collison pending.
Please use your eyes.

I expect everyone actually does use their eyes.

Folks probably don't see something on an AIS screen, and then suddenly choose to ignore it from then on. Or suddenly forget it's there -- although I suspect forgetting is maybe more likely than intentionally dismissing.

For example, we don't use AIS to the exclusion of all (or any) other info sources. Including Mark I* eyeballs. And for the most part, I'd guess an AIS factoid -- benign boat on the display, flashing red boat on the display, audible alarm, whatever... is generally just an additional alert mechanism, over and above basic watch standing, radar alarms, depth alarms, etc.

I haven't seen anyone here say they love AIS and put their blinders on at the same time.

Although I don't have PSN's interaction history with seeming bozos!

Looks like only a few folks here seem to be saying they don't want no steenkin' additional watch-standing aid. Lots o' room for personal choice in that department...

-Chris