AIS overlay radar ???

Here was one incident, where there were a number of errors by the watch stander. Not really the "fault" AIS, but that Radar and Visual sites were not involved. The VTS broadcast was ignored, no second watch stander etc. (Perhaps not even a good command of English!).

Not the "fault" of AIS. As has been noted, AIS is just one more tool. I don't overlay Radar on an AIS screen--I have a a separate AIS screen, and it is one of several (including IR, at night), Radar, Radio broadcasts.

Not a reason to avoid AIS.
 
From the article - "Rickmers Dubai’s OOW was alone on the bridge and he did not see Walcon Wizard. He did not keep a visual lookout or monitor the radar. Instead, he relied solely on AIS information for collision avoidance, which neither Kingston nor Walcon Wizard were transmitting." - That's not an AIS issue that's an idiot at the watch issue. I have AIS and am not at all reliant on it to detect everything. I do however pretty much count on the vessels shown by AIS to be present but no one in their right mind would assume the blank space on the screen is empty.
 
let me rephrase; an over reliance on AIS. Heck, i'm using AIS right now. I'm just a big fan of using all available means and knowing the limits and errors that can pop up in those means.
 
you can run an AIS app like Boat Watch on you iPAD that will give you a general idea of whats moving around you in in the fog as a supplement to your radar overlay on a chart plotter, as long as you have a an internet connection via your cell service. It was quite useful the last time we went into Astoria on our way down from Cathlamet. We left in clear weather but hit dense fog from the dredge all the way to the West Basin.
Not the most elegant solution but useful
Best
Eric
 
cmetzenberg":342tlzrz said:
AIS is a vhf broadcast information from vessels that broadcast AIS information. The vast majority of these vessels are commercial. The data broadcast can include vessel name, call sign, MMSI, course, speed, cargo, ect. This data should NEVER be used for collision avoidance and maneuvering purposes, it is only as good as the sensors on the vessel broadcasting it. For pleasure boaters the only useful data AIS will give you is the names of vessels near you, this is handy if you need to hail them over the radio. Asides from that, useless. As far as the AIS text messaging service goes, no one in industry uses it or ever checks it, kinda like digital selective calling (vhf-dsc).
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">>>>... This data should NEVER be used for collision avoidance and maneuvering purposes, it is only as good as the sensors on the vessel broadcasting it. For pleasure boaters the only useful data AIS will give you is the names of vessels near you, this is handy if you need to hail them over the radio. Asides from that, useless."
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Conrad, I could not disagree more.

Actually, AIS range is often times, greater than the radar range.

I run radar full time, and since the addition of the AIS it is also run full time. The radar runs on an overlay on the plotter, or sometimes on a separate screen, depending on condition and AOO (area of operation). AIS is provided by 2 sources, Standard Horizon GTX2150 vhf and a Vesper Marine Watchmate Vision - A stand alone B series with it's own monitor. The AIS data is also displayed on the MFD screen and defaults to the 2150 input if the Watchmate is not on.

The time it takes to run a curser on the MFD to an AIS target and touch "display AIS" button is only a few seconds. In that time I have CPA (closest point of approach) and TCPA (time to closest point of approach). In that same time, I would be half way to getting the radar only screen up, let alone setting up the MARPA.

Oh, by the way, at the same time, I also have the vessel name, MMSI#, and one button calling via DSC to that vessel. And, lets just say it is totally clear weather, BUT, the vessel is a ferry moving at 22 knots, coming around the corner at Shaw island, and there is a tug and tow approaching visible on radar and to me. I can determine speeds of both vessels, (the ferry I can't see, and the tug I can) and can see they will meet at the narrowest part of the pass, just when I would be there.) Now I can pre-determine, that I don't want to be there then, but I only know that from what I can determine with the AIS. RADAR does not see the ferry, on the other side of the point.

When crossing the Strait of Juan de Fuca, with the plotter set at 25 miles, and radar set at 12, the AIS is set on the 25 screen, I can see a string of Targets, east bound lined up from Port Angels, and in a few seconds, can get TCPA and CPA and determine if I want to maintain speed or adjust, to clear in the greatest space.

Would I use the AIS for "collision avoidance and maneuvering purposes", absolutely. Would I rely on it solely? No way. Is it a necessary tool? I guess that is a personal opinion, (and everyone is entitled to have their own), but when those little triangles are 50 times my size and traveling at 2 to 4 times my usual cruising speed, (6 or 12 knots), I will use what ever adjunct I have available to be sure I am out of their way.

You are right about the digital calling with DSC, not everyone knows how to use it, but even without, the AIS gives the vessel name, and that works almost as quick. It is nice having that info while that target is still out there 10 min or more away.

As to using a phone app for AIS info. Yes it works, HOWEVER, there can be a significant time delay, and at 20+ knots, that little triangle, can be 2-3 miles closer to you than you think when you look up from your phone. Works fine if you are sitting at the marina nad wondering what ship that is going by. More scary if you are looking up at the bow, and can't see the bridge. :shock: :oops: :cry

Harvey
SleepyC :moon

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Alternatives to AIS overlay are available:

1. The Vesper Watchmate (B series Transponder) comes as a stand alone monitor, about 7"diag view, with a very basic coastal outline picture, allowing the ability to both zoom in or out, and to see the targets in relation to both you and the land masses in the area. The Watchmate has capability to show either heading up or north up display.

2. The Standard Horizon GX 2100 or 2150 has, in AIS display mode, a screen that is also zoomable, and shows the targets in relation to your vessel. The display is in relative to your position and I believe is based on heading up.

As a personal note, I do not run radar with AIS overlay, as I prefer to keep those separate. Radar keeps an eye on what is close, Generally 6 miles or less, and AIS keeps track of the big guys that would even notice the bump if they ran over me.

Harvey
SleepyC :moon

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"Would I use the AIS for "collision avoidance and maneuvering purposes", absolutely. Would I rely on it solely? No way."
I guess i shouldn't have been so firm in original statement because what just wrote is basically the point i'm trying to make. I'm saying that it would not be prudent to attempt a close pass to any traffic off AIS data alone.

If you feel like doing some reading, here is a place you can read about AIS various AIS issues. Again, the big issue; the accuracy of broadcast info.

http://www.nautinst.org/en/forums/ais/ais-issues.cfm
 
Thanks for that link. Interesting reading for sure. Much of what I found was what I would consider fairly old information ( 2003, 2005, 2010 and much of it undated.)

There is a common thread, AIS is not without fault, however, those faults appear to be operator caused (from the Coast Guard giving a wrong instruction to OOW not ensuring accurate info entered into the Class A systems).

Also, understanding where the AIS info is coming from. In the post "A Pinch of Disbelief" from the Nautical Institute (your link),
http://www.nautinst.org/en/forums/ais/a ... pinchofdis
the AIS info source is web based, not real time AIS unit, and there is no knowing what the delay is, so the discrepancies are explainable, as in positioning or ship movement, not in AIS output errors.

A significant benefit is noted:

"AIS use has virtually eliminated the "Ship on my port bow" VHF radio calls. Now, when ships have traffic issues, they call the ship by name. I believe that the use of AIS has reduced clutter on channel 16 VHF. It should also reduce the hazard of a ship thinking a meeting arrangement has been agreed with a ship, only to find out that they were talking to a different ship than they thought."
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As for me and my vessel, AIS stays on board and in use. It does not preclude the edict to maintain a proper, alert and active watch from the wheel.

Harvey
SleepyC:moon

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Flir would be nice, for sure. I'd love one but I think they are two different animals, and I would not give up my AIS for a FLIR IRS.

Guess it depends on what you are doing mostly.

Harvey
SleepyC :moon

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Harvey,
An excellent write up! Thank you! I have compared the internet AIS and real time reception--some times it is close-other times a significant delay--but rarely right on spot with the on board AIS.

I have the cheapest type of FLIR--and for me, the most useful. The hand held scope. I have to have an open window (disadvantage), and not be able to look at other modalities. I find it useful at close ranges--less than a mile, realistically a few hundred yards. For example coming into an anchorage at dark, where there are few anchor lights. For example both my own canal, the Isthmus (two harbors) at Catalina etc.

FLIR does not extend your range much in fog or smoke. The resolution even of $10,000 units is not good. I have only seen the lower end units in use on small boats. FLIR has its place, but to be the best, you want a unit which pans tilts and zooms. Resolution is going to be 640×480. These units run between $12,000 and $17,000. There are some fixed 320 x 240 units a little over $3,000.

I feel that a unit like the Vesper Watchmate gives far more information for the $$…. There are times when a good antenna and receiver can receive AIS from as much as 40 miles out--regularly from 15 miles out. Yes, there are times the AIS transmitters are turned off. But from a lot of personal experience, wondering what a ship is doing, even with MARPA, it helps a heck of a lot to have any information! For example, many times I have had to call "Ship at XXXXX Lat and XXXXXLong, this is vessel "Thataway"--do you have me on your radar? I am a 46 foot sailing vessel, At Lat XXXX, and Long XXXX proceeding at a speed of 7 knots and a course of 280 degrees."

Then you wait for a response. How many watch standers know what their lat and long is? If you just have the name of the ship, even a description, it makes things so much easier……

Again--one modality of many.
 
Thank you Bob,

I have played with a couple of handheld units only, but not on the water. FLIR is on the list of "would be nice" but it is somewhere down under a good IS Binocular set which I would have much more use for.

As to AIS range, when on the strait, I frequently see AIS targets on the 24 mile screen. I usually check them for direction of travel, and maybe TCPA.

Harvey
SleepyC :moon

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I agree, I use the stabilized binoculars far more often than FLIR. (I also have a gen 2 night vision scope--and rarely use it either. )
 
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