OK No Bites so a bit of rambling on
OK, One of the reasons I was asking was my recent experience on a 165' research vessel. AIS was a key player in the smooth sailing we had. That along with ARPA or a very fine radar set (times 2 of course).
THere are some affordable class B AIS transponders becoming available in Europe for about 500 Euro (make that < $750). Someday available to us in the US.
I can buy an AIS receiver now for around $180 which will show the AIS transponder equiped vessels (all over 300 GT by law) on some charting programs/Chartplotters.
THis would then display the position and heading including a projection of where the vessel will be (if nothing changes) in a selectable time. Plus give the vessel name, course, speed and an estimate of the cpa and tcpa (closest point of approach and time of cpa)
Think about being in a fog and knowing that that freighter will come within 1/2 mile of you. You could call them and work out a passing plan.
Or if you have a transponder then their AIS will show your boat on their nav systems and they might just call you to work out a plan.
Spending a week on and off the bridge of this research ship let me learn many things. Thus I now have a beading sensor wired into my radar so that I can use Marpa, plans on adding AIS in receive mode at first and an AIS transponder later plus plans for monitoring both channel 16 and 13 which this ship did. 13 is very good for setting up passing plans.
It does not matter too much here on the Columbia river but crossing the bar and the coastal trip up to the San Juans these aids would be a blessing.
We crossed the Columbia Bar in the night and a fog. There were dredges active which we were able to call by name and to plan how to pass. ....
ramble mode off
OK, One of the reasons I was asking was my recent experience on a 165' research vessel. AIS was a key player in the smooth sailing we had. That along with ARPA or a very fine radar set (times 2 of course).
THere are some affordable class B AIS transponders becoming available in Europe for about 500 Euro (make that < $750). Someday available to us in the US.
I can buy an AIS receiver now for around $180 which will show the AIS transponder equiped vessels (all over 300 GT by law) on some charting programs/Chartplotters.
THis would then display the position and heading including a projection of where the vessel will be (if nothing changes) in a selectable time. Plus give the vessel name, course, speed and an estimate of the cpa and tcpa (closest point of approach and time of cpa)
Think about being in a fog and knowing that that freighter will come within 1/2 mile of you. You could call them and work out a passing plan.
Or if you have a transponder then their AIS will show your boat on their nav systems and they might just call you to work out a plan.
Spending a week on and off the bridge of this research ship let me learn many things. Thus I now have a beading sensor wired into my radar so that I can use Marpa, plans on adding AIS in receive mode at first and an AIS transponder later plus plans for monitoring both channel 16 and 13 which this ship did. 13 is very good for setting up passing plans.
It does not matter too much here on the Columbia river but crossing the bar and the coastal trip up to the San Juans these aids would be a blessing.
We crossed the Columbia Bar in the night and a fog. There were dredges active which we were able to call by name and to plan how to pass. ....
ramble mode off
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Cory B
Sustaining Member
QuickBite
We took a trip up North and back this last summer (leave Columbia River, take a right, take another right at JuandeFuca) with a new Raymarine chartplotter & radar, and integrated SeaCAS AIS. Although AIS may be required on all large vessels, it unfortunately doesn't mean you are going to recieve it. Most commercial ships we'd pick up 3-8 miles out, but others we'd pick up at 1/2 mile, and some we'd lose again within 1/4 mile. My theory is that the AIS broadcasting antennas were sometimes attached adhoc on different parts of the superstructure that sometimes were blocked.
The data being broadcast on AIS by vessels often was incomplete or inaccurate. Many did not include their names (but did still include their digital calling ID). A few were broadcasting incorrect heading or speed info... ie claiming they were anchored while pushing a huge bowwave in the middle of the Straights. I don't recall an instance where the position broadcast was noticeablely wrong, although they could have been broadcasting that they were still in China, and I just didn't have our chartplotter out on wide enough view.
The MARPA/ARPA tech built into the latest Raymarine stuff was sometimes useful (CPA) if used actively, but the "guard-zone" stuff was pretty useless.
That being said, we consistently picked up signals from a good distance from both Washington state and BC ferries. Its a good tool, but shouldn't be used in isolation, but we all knew that already.
- Cory
We took a trip up North and back this last summer (leave Columbia River, take a right, take another right at JuandeFuca) with a new Raymarine chartplotter & radar, and integrated SeaCAS AIS. Although AIS may be required on all large vessels, it unfortunately doesn't mean you are going to recieve it. Most commercial ships we'd pick up 3-8 miles out, but others we'd pick up at 1/2 mile, and some we'd lose again within 1/4 mile. My theory is that the AIS broadcasting antennas were sometimes attached adhoc on different parts of the superstructure that sometimes were blocked.
The data being broadcast on AIS by vessels often was incomplete or inaccurate. Many did not include their names (but did still include their digital calling ID). A few were broadcasting incorrect heading or speed info... ie claiming they were anchored while pushing a huge bowwave in the middle of the Straights. I don't recall an instance where the position broadcast was noticeablely wrong, although they could have been broadcasting that they were still in China, and I just didn't have our chartplotter out on wide enough view.
The MARPA/ARPA tech built into the latest Raymarine stuff was sometimes useful (CPA) if used actively, but the "guard-zone" stuff was pretty useless.
That being said, we consistently picked up signals from a good distance from both Washington state and BC ferries. Its a good tool, but shouldn't be used in isolation, but we all knew that already.
- Cory
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Antenna and flag
My experience was better than yours (good to know the limits that you experienced).
Would you think it fair to say that the US flagged vessels took AIS more seriously than non-US flagged vessels?
Can you comment on your antenna placement? (masthead, Deck level, shared with VHF radio etc) And if you think that was a limit for reception.
Inputs to an AIS transponder "should" be as good as the equipment installation. Heading from the gyro compass, COG, speed from the (typically) built-in GPS. The vessel name and status (under weigh) are human inputs and subject the operating style of the ships officers.
And as you note, there is nothing that replaces seamanship in all of its forms.
As a side note the research vessel I was on has over 60 years of experience in the Captain and 1st mate. Both have 1000 ton (or more) unlimited licenses. The Captain was very professional. You could see his competence in seamanship, ship operations and navigation. The 1st had Captained the ship for many years in the past and learned his seamanship before GPS and other electronics. You could see that he was competent in current electronics but had a depth of knowledge from before them. The 2nd mate was just out of school. She was competent but lacked their depth of experience. However her grasp of the electronics showed that she comes from the video game generation. I'd trust them all.
Visual watch was 24/7, radar and chart plotter consulted minute by minute and paper charts open and marked frequently. The log book updated at every need. Very professional.
My experience was better than yours (good to know the limits that you experienced).
Would you think it fair to say that the US flagged vessels took AIS more seriously than non-US flagged vessels?
Can you comment on your antenna placement? (masthead, Deck level, shared with VHF radio etc) And if you think that was a limit for reception.
Inputs to an AIS transponder "should" be as good as the equipment installation. Heading from the gyro compass, COG, speed from the (typically) built-in GPS. The vessel name and status (under weigh) are human inputs and subject the operating style of the ships officers.
And as you note, there is nothing that replaces seamanship in all of its forms.
As a side note the research vessel I was on has over 60 years of experience in the Captain and 1st mate. Both have 1000 ton (or more) unlimited licenses. The Captain was very professional. You could see his competence in seamanship, ship operations and navigation. The 1st had Captained the ship for many years in the past and learned his seamanship before GPS and other electronics. You could see that he was competent in current electronics but had a depth of knowledge from before them. The 2nd mate was just out of school. She was competent but lacked their depth of experience. However her grasp of the electronics showed that she comes from the video game generation. I'd trust them all.
Visual watch was 24/7, radar and chart plotter consulted minute by minute and paper charts open and marked frequently. The log book updated at every need. Very professional.
Cory B
Sustaining Member
Most of the vessels we had trouble receiving were large commercial vessels, so I'd imagine they were most foreign flagged. Ferries, local tugs, and large pleasure vessels were no problem.
We had a standard VHF whip antenna mounted on the stern rail dedicated for AIS. Perhaps some of the flakiness we saw with the larger vessels may have been reduced with a masthead antenna, but my hunch is even that may not have been enough. I'm pretty confident our AIS reciever was functioning properly, and that the antenna connections were solid (short coax lead as well).
For heading data we used the existing fluxgate compass from our autopilot. A full-fledged fast updating rate-gyro type compass might have made MARPA more useable.
Seeing how we are both in Portland, feel free to shoot me a message via the EYO site if you want to compare notes.
- Cory
We had a standard VHF whip antenna mounted on the stern rail dedicated for AIS. Perhaps some of the flakiness we saw with the larger vessels may have been reduced with a masthead antenna, but my hunch is even that may not have been enough. I'm pretty confident our AIS reciever was functioning properly, and that the antenna connections were solid (short coax lead as well).
For heading data we used the existing fluxgate compass from our autopilot. A full-fledged fast updating rate-gyro type compass might have made MARPA more useable.
Seeing how we are both in Portland, feel free to shoot me a message via the EYO site if you want to compare notes.
- Cory
Howard Keiper
Moderator
AIS operates in the 162 Mhz band like any other VHF radio and therefore should be treated the same. Splitters however, are not recommended...put the antenna as high as is convenient. I think it's way more useful to know where the AIS mandated (large, no matter how you measure them) ships are and what they're up to, rather than vice-versa...you need a receiver, not a transponder. At the moment, the Europeans are way ahead of us in the overall development of AIS technology. In my opinion, AIS is far more useful than ARPA or it's variants. However, MARPA is often available as a built in feature of many recent vintage radars, free for nothin...
Howard Keiper
Sea Quest
Berkeley
Howard Keiper
Sea Quest
Berkeley