Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 21-05-2013, 07:24   #496
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Like I said, I don't expect any useful information from AIS when vessels around are maneuvering. The system doesn't know whether targets are following channels, and doesn't know when that turn is going to stop, and therefore can't produce any meaningful warnings, as far as I can figure out.
And, AIS won't tell you about the guy in the open fishing boat sitting in the middle of your path under the erroneous assumption that fishing boats have the right of way. I once went over to a guy in an open skiff anchored in the middle of the Miami shipping channel and told him to get out of there as there was a cruise ship coming in. He angrily refused to move and the cruise ship was just able to squeeze by the guy, who still didn't budge. When I left the Pilot Boat was parked next to the guy yelling at him.
__________________

__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 21-05-2013, 07:32   #497
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: Please turn your AIS off when docked/moored/anchored

I am very much pro alarms but only valid ones, with false alarms prevented. A false alarm decreases safety.

In busy areas I still use AIS and alarms. I suppress all alarms for stationary targets which I avoid by steering around them The alarms are often from ships just outside the nearest group but which are heading into that group. Or they are coming out of an entrance, around a land point, from behind an obstruction etc. Sometimes even from mobiles that the radar can't see like when the mobile is behind a land point. This is where the real advantage of active transponders is as compared to passive systems like radar.


For those still ranting on moral and rights etc.: our boats and ships have rights too you know. Ask any old salt and he will tell you how his boat talks to him or lets him feel what is good and what not. After hundreds of years of abuse a group of engineers finally gave boats their voice and means to talk to each other about things like how many people they carry, what cargo or where they are heading to at which speed. Or how tight a turn they can make or how fast they can go. Or that they are at a well deserved rest at their mooring. Now I hear talk about shutting that down, which would be a gross form of discrimination and a step back into times that we shouldn't be proud of. Respect them and they will take care of you too!
__________________

__________________
s/v Jedi is offline   Reply With Quote
Old 21-05-2013, 07:39   #498
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: PORTUGAL
Posts: 20,222
Images: 2
pirate Re: Please turn your AIS off when docked/moored/anchored

IOW the only 'Common's' applicable is.... Sense...

Sorry guys still learning to read.. big words (3+) confuse me
__________________


Born To Be Wild
boatman61 is online now   Reply With Quote
Old 21-05-2013, 08:15   #499
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,755
Re: Please turn your AIS off when docked/moored/anchored

One thing I personally would like to see on 'yachting alarms' is rather than just a generic buzzer, the AIS alarm says "AIS, AIS, AIS" and the engine overheat alarm says "overheat, overheat, overheat" and the radar guard zone say 'guard zone, . . . ", the autopilot failure alarm say "autopilot, ....". This is more common in some other application areas I am familiar with, and not all that hard to implement.

Regarding AIS alarms, I personally find Vesper's general settings very effective (e.g. I rarely get false positives and also rarely get false negatives), except in it's dealing with 'stationary targets'.

In that case, with the current alarm filtering set-up, it seems there is just a simple and direct trade-off. If you have stationary targets 'turned off' (eg filtered out) you are going to get false negatives (the fishing boat picking pots) and if you have them turned on you are going to get 'false positives' (the docked boats). Which you choose seems a personal decision which I think probably reflects: #1 whether you think false negatives are better or worse than false positives (Which may have something to do with how often you sail in deep fog) and #2 what the relative proportion in your areas is of false positives (docked boats) to false negatives (boats picking pots or waiting for Warf schedules) is, and #3 it's probably less important if you are mostly day sailing and more important if you are overnight (or longer). I personally generally prefer to error toward false positives, and in the case of stationary targets that is also in line with where and how I generally sail (not all that many docked boats, and longer legs).

We have all already agreed that the stationary target filter could be improved in several ways (some of them very simple and some more complex), to decrease this trade-off between the rate of false positives and negatives. Ideally the filter should be smart enough that there really is not a trade-off, and that seem (to me) to be achievable.

Regarding depth sounder alarms . . . I think it's generally a miserable data type for alarms because it reports what you already have rather than being predictive. In well charted places, it would be better if your chart plotter looked say 5secs in front and alarmed if it saw shallow water there; or in poorly charted places, if you had a forward looking sonar. Another interesting aspect of shallow water navigation and depth alarms came out of the Low Speed Chance incident, which was that really they should incorporate a sea state factor. Of course the sounder alarm is useful if your navigation plan is to sail a depth contour or a 'hazard clearing depth', but my impression is that those are rarely used navigation approaches today.

My own personal feeling about and use of alarms has changed dramatically over the years. I think on our first voyages the only alarm we had was engine overheat. I now use quite a number of alarms. I have never really thought about why that changed. In part I guess it is because I am more aware now of my potential to fail to focus on the right thing, in part it's because I have been exposed to accident investigations and best practices from other fields, and in part it's because the gear has gotten better. I am well aware that my current use of alarms is somewhat untypical, which is one reason I brought it up for discussion.
__________________
estarzinger is offline   Reply With Quote
Old 21-05-2013, 08:45   #500
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by estarzinger View Post
One thing I personally would like to see on 'yachting alarms' is rather than just a generic buzzer, the AIS alarm says "AIS, AIS, AIS" and the engine overheat alarm says "overheat, overheat, overheat" and the radar guard zone say 'guard zone, . . . ", the autopilot failure alarm say "autopilot, ....". This is more common in some other application areas I am familiar with, and not all that hard to implement.

There is one alarm on our boat that whenever I do something stupid she says "dumbass, dumbass, dumbass". That alarm is ALWAYS going off and I can't find any way to quiet it.

Regarding AIS alarms, I personally find Vesper's general settings very effective (e.g. I rarely get false positives and also rarely get false negatives), except in it's dealing with 'stationary targets'.

In that case, with the current alarm filtering set-up, it seems there is just a simple and direct trade-off. If you have stationary targets 'turned off' (eg filtered out) you are going to get false negatives (the fishing boat picking pots) and if you have them turned on you are going to get 'false positives' (the docked boats). Which you choose seems a personal decision which I think probably reflects: #1 whether you think false negatives are better or worse than false positives (Which may have something to do with how often you sail in deep fog) and #2 what the relative proportion in your areas is of false positives (docked boats) to false negatives (boats picking pots or waiting for Warf schedules) is, and #3 it's probably less important if you are mostly day sailing and more important if you are overnight (or longer). I personally generally prefer to error toward false positives, and in the case of stationary targets that is also in line with where and how I generally sail (not all that many docked boats, and longer legs).

Unless the pot picker was operating next to a marina, I still don't see why a CPA/TCPA filter won't pick that up. And if the pot picker starts to move, then no problem.

We have all already agreed that the stationary target filter could be improved in several ways (some of them very simple and some more complex), to decrease this trade-off between the rate of false positives and negatives. Ideally the filter should be smart enough that there really is not a trade-off, and that seem (to me) to be achievable.

Regarding depth sounder alarms . . . I think it's generally a miserable data type for alarms because it reports what you already have rather than being predictive. In well charted places, it would be better if your chart plotter looked say 5secs in front and alarmed if it saw shallow water there; or in poorly charted places, if you had a forward looking sonar.

OK, I don't understand this well. All chart plotters (using vector charts) allow one to set colors for shallow/deep areas. Any routes through an area with shallow depths should be sussed out before entering. Most chartplotters and computer charting will "run" a route for you and warn you in advance about obstacles and danger areas. And 5secs is not going to give someone on the bow clearing a sheet enough time to avoid the problem.

Forward looking sonars are helpful this way, but probably draw more power than a chartplotter or computer.


My own personal feeling about and use of alarms has changed dramatically over the years. I think on our first voyages the only alarm we had was engine overheat. I now use quite a number of alarms. I have never really thought about why that changed. In part I guess it is because I am more aware now of my potential to fail to focus on the right thing, in part it's because I have been exposed to accident investigations and best practices from other fields, and in part it's because the gear has gotten better. I am well aware that my current use of alarms is somewhat untypical, which is one reason I brought it up for discussion.

I would suggest that you have buried yourself (in the engineering sense) in the possibilities of alarms and their filtering and have become lost in that forest. You may be conflating your evolved preference for more reliance on alarms with your engineering geekery on making them perfect.

There are way too many variables there. For example, you are attempting to imagine accurate and customized alarms for a boat with little to no electrical generation or capabilities. Our boat is different than yours and when something has an alarm, very specific warnings display on numerous devices around our boat. Even if they all rang the same audio tone (which they do not), all I have to do is turn my head and look at the closest display to know exactly which part of the boat is crying and exactly what is wrong with it.

So I would correctly be able say that this has been solved, while you can equally correctly say it hasn't. In this case, your choice of outfitting is the real variable that hasn't been addressed. And I don't mean that in a derogatory way at all.

On the other extreme, I suspect cruise ships never have crew running through dozens of decks looking for just what alarm is ringing.

.........
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 21-05-2013, 09:24   #501
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,755
Re: Please turn your AIS off when docked/moored/anchored

>>Any routes through an area with shallow depths should be sussed out before entering.

Have you never ever made the mistake of planning a route and not zooming in all along that route and missing a small hard spot? I have made that mistake. Or of a small hard spot being closer than 'comfortable' to the route, which your auto inspection routines might well not catch.

>>Most chartplotters and computer charting will "run" a route for you and warn you in advance about obstacles and danger areas.

Have you never gotten pushed off your planned route by a wind shift or current? I have. And how many plotters will anticipate tacking and gybing across a route line?

>>And 5secs is not going to give someone on the bow clearing a sheet enough time to avoid the problem.

Geeze, fine, set it to 10 seconds.

>>Unless the pot picker was operating next to a marina, I still don't see why a CPA/TCPA filter won't pick that up.

We have already discussed this. I don't see any point in rehashing it.

>>I would suggest that you have buried yourself (in the engineering sense) in the possibilities of alarms and their filtering and have become lost in that forest. You may be conflating your evolved preference for more reliance on alarms with your engineering geekery on making them perfect.

I would suggest that I realize that I can fail and make mistakes, and that 'good alarms' (ones with low false rates) can help me when I do fail.

>>you are attempting to imagine accurate and customized alarms for a boat with little to no electrical generation or capabilities.

First, just as a very very small point, actually Hawk has a relatively large battery bank (800ah in the house) and relatively large generation capability (two alternators). It's our energy USE that is low. Alarms draw essentially zero incremental power. And 'good ones' are not all that hard to engineer.

Second, please to go back and recognize that I did explicitly said I was just explaining my alarm use and explicitly said I was "not trying to suggest any of you should change your operating practices regarding alarms."

Third, I guess your point here is that because you have big screens available you will always be aware of everything? Well, I will only comment that two of the vessels in recent accident investigations also had big screens.
__________________
estarzinger is offline   Reply With Quote
Old 21-05-2013, 09:31   #502
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,757
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by colemj View Post
.........
I have forward looking sonar, and my new chart plotter will sound an alarm if I am running into what the electronic chart says is shallow water.

The forward looking sonar is useless for this purpose (it has alarms, but I would never use them).

The chart plotter is excellent, and I agree with Evans that this is probably the best depth alarm.

But the regular depth sounder alarm is terrifically useful, if you take the time to set it up for every passage. My old Raymarine gear had this, too, and I loved it. I would generally leave it on 3 meters, which would usually give enough time to figure out what was going on and change course. If you're off somewhere off soundings, then you could set it for 10 meters, so that you would hear about it if you screwed up your navigation and found yourself actually some place closer to land. This would have saved Jean Socrates' bacon a few years back, when she ran aground off San Diego in her sleep because her autopilot flipped off. I'm sure the equipment she had on board was capable of sounding such an alarm.

You never need a depth alarm if you're careful in your navigation and pilotage, and if you keep an eye on the sounder. I've never been saved by one; hardly ever been surprised by one. But as Evans said -- it's great to have a backup. I am a BIG believer in depth alarms.
__________________
Dockhead is online now   Reply With Quote
Old 21-05-2013, 09:52   #503
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Please turn your AIS off when docked/moored/anchored

OK Evans. My intent wasn't to be confrontational. I certainly am not aware of everything at all times and can experience the problems you mention. I have to admit, though, that I am meticulous about running routes when I create them. I also continue to run them at detailed zoom routinely while underway. But even though I am anal about that, I admit that it is always possible I will forget or even miss something sometime.

Let me boil it down to this: I don't think there will ever be alarms and filtering systems so specific and accurate as to work in all situations. There will always be false alarms and missed alarms - both are a problem. I DO think it is fun to think about and imagine - that is the technical geekery I mentioned.

We don't have any big screens. They are quite small, actually - 4" mfd's with the main function of navigation instrument display. Each display draws 0.15amps, are waterproof and sunlight readable and you can get two for the same price as an iPad. Our plotter display is 8", but I don't think that qualifies as large.

My point there was that when any "beeping" goes on, it isn't blind - a description of what is having the problem and what that problem is is displayed.

You mentioned that blindness of a simple beeping was a problem, and I simply pointed out that that was the situation on your boat and that solutions did exist. I find visual descriptions easier to understand and recognize than something shouting "guard zone, guard zone" which I may have trouble understanding if two alarms are off at once or I am not adjacent to the alarm speaker.

I recognize you aren't trying to change my SOP's regarding alarms, and I am not trying to change yours. I simply meant to point out additional solutions to your quest, as well as offer my opinion on its chance of success. I apologize if I am being presumptuous.

I bet there are also examples of two vessels in accidents that did not have big screens. As well as ones with audible alarms active. I don't understand that point - it seems like cherry-picking.

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 21-05-2013, 09:57   #504
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,888
Images: 4
Re: Please turn your AIS off when docked/moored/anchored

For what it's worth, I think the occasional false alarm is a good thing. It tests your equipment and gives you something to practice with. It's when the alarms distract you from something critical that they become a problem.

On NavMonPc I have three classes of audio alarms, and the soundfiles can be modified by the user. The default AIS alarm is a klaxxon sound but there's no reason the AIS alarm couldn't shout "AIS ALARM!". I've noticed that some audio alarms on airplanes use voice annunciation.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 21-05-2013, 14:05   #505
Registered User
 
S/V Alchemy's Avatar

Join Date: May 2008
Location: Toronto
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,577
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by estarzinger View Post
One thing I personally would like to see on 'yachting alarms' is rather than just a generic buzzer, the AIS alarm says "AIS, AIS, AIS" and the engine overheat alarm says "overheat, overheat, overheat" and the radar guard zone say 'guard zone, . . . ", the autopilot failure alarm say "autopilot, ....". This is more common in some other application areas I am familiar with, and not all that hard to implement.
Needless to say, I concur. Buzzers are for chumps! You need an alarm that self-identifies.

The world encompassed: The buzz on boat alarms

(I still can't believe this thread is going...)
__________________
Can't sleep? Read www.alchemy2009.blogspot.com for fast relief. Can't read? Avoid www.volumesofsalt.blogspot.com, because it's just personal reviews of sea books.
S/V Alchemy is offline   Reply With Quote
Old 21-05-2013, 14:49   #506
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,755
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by S/V Alchemy View Post
Needless to say, I concur. Buzzers are for chumps! You need an alarm that self-identifies. The world encompassed: The buzz on boat alarms

LOL, ok you had the idea first. But I want a really sexy female voice for my alarms.

(I still can't believe this thread is going...)

I have been promised a free ball cap if I can stretch it out to 50 pages!


(just kidding).
.............
__________________
estarzinger is offline   Reply With Quote
Old 21-05-2013, 15:54   #507
Registered User
 
S/V Alchemy's Avatar

Join Date: May 2008
Location: Toronto
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,577
Re: Please turn your AIS off when docked/moored/anchored

I vote for Lauren Bacall's voice saying "We have a small fire. You know how to put out a fire, don't you, Skipper? Just pull the pin on the extinguisher...and aim."



What? She's a sailor!

And good luck with that cap.
__________________
Can't sleep? Read www.alchemy2009.blogspot.com for fast relief. Can't read? Avoid www.volumesofsalt.blogspot.com, because it's just personal reviews of sea books.
S/V Alchemy is offline   Reply With Quote
Old 21-05-2013, 16:07   #508
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Mine would be a ' Dalek' type announcement ( geting increasingly hyper ) , Collision imminent , Collision imminent Collision ........

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 21-05-2013, 16:13   #509
Registered User

Join Date: Jul 2006
Posts: 3,949
Re: Please turn your AIS off when docked/moored/anchored

Or it could be a voice like a friend has in his Mercedes that sounds like a German female SS officer: "Turn left now!"
__________________
Kettlewell Cruising
Kettlewell is offline   Reply With Quote
Old 21-05-2013, 16:23   #510
Registered User
 
cheoah's Avatar

Join Date: Sep 2010
Location: North Carolina, USA
Boat: Moccasins and pony
Posts: 996
Re: Please turn your AIS off when docked/moored/anchored

Quote:
Originally Posted by Kettlewell View Post
Or it could be a voice like a friend has in his Mercedes that sounds like a German female SS officer: "Turn left now!"
As long as it doesn't sound like Siri. Talk about evolving technology....
__________________

__________________
cheoah is offline   Reply With Quote
Reply

Tags
ais

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:42.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.