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Old 04-01-2012, 13:24   #46
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Re: AIS experience offshore?

FWIW,

In our short term usage of AIS (NSW coast), we have not seen any merchant vessels who were not transmitting AIS data. However, we have seen a surprising percentage who were broadcasting erroneous info, ie "underway" when anchored and vice versa. Inspection of their SOG usually sets things straight.

I've found it quite useful in sorting out activities around busy ports with a big field of anchored vessels.

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Old 04-01-2012, 13:26   #47
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Quote:
Originally Posted by DotDun

Please qualify the statement.

Might be true if you are only interested in seeing <1% of the floating objects on the water.
What was meant that inn terms of benefit against cost it ranks above radar and I'd agree. On a budget conscious fit out I'd pay for it before radar.

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Old 04-01-2012, 13:40   #48
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Re: AIS experience offshore?

Quote:
Originally Posted by hellosailor View Post
Mark, maybe 4200 for one that feeds into another display, but standalones are more like $500, and full transceivers $800++.

I think I'd hold out for a standalone, and probably a transceiver since it just *might* be even more useful by ringing the other guy's collision alarm as well as mine.

Figuring a transceiver is still just "cell phone brains" plus a VHF...$900 probably will keep coming down a bit closer to $200 if volume and marketing allows it.
The only difference between an AIS receiver built into a VHF, and a full transceiver would be just 1 circuit to encode and transmit position info from GPS signal. Probably easiest to build into VHF and GPS combo unit, as in the Standard Horizon example you cannot gaurantee the user will plug into GPS.

A user ID unit that plugs into an existing DSC capable VHF for class B transceiver should be on the market soon.........
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Old 04-01-2012, 14:16   #49
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pirate Re: AIS experience offshore?

Quote:
Originally Posted by colemj View Post

But to each his own - if you were out cruising and had a $200 budget, I am positive that on your very first passage through shipping areas, you would change your mind about waiting for a full, independent, dedicated transceiver to drop to that price and would be installing a $200 black box in the next port.

Mark
Well I've been crossing the English Channel pre AIS and GPS... and to be honest neither have changed they way I do it... and I've been out there in fog with the hooters going... but I'll not rush out to buy one... other essentials to deal with first.
Maybe one day when they do a H/H like the GPS... and as cheap.
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Old 04-01-2012, 14:24   #50
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Re: AIS experience offshore?

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Originally Posted by boatman61 View Post
Well I've been crossing the English Channel pre AIS and GPS... and to be honest neither have changed they way I do it... and I've been out there in fog with the hooters going... but I'll not rush out to buy one... other essentials to deal with first.
Maybe one day when they do a H/H like the GPS... and as cheap.


of course they dont, what they do is make it easier and simpler and less risky. thats all.
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Old 04-01-2012, 14:37   #51
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Re: AIS experience offshore?

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Originally Posted by Jim Cate View Post
I've found it quite useful in sorting out activities around busy ports with a big field of anchored vessels.
This starting sound like space travel, having to check the satellites positions before going into orbit.
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Old 04-01-2012, 14:44   #52
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Quote:
Originally Posted by evm1024

If I were in control of such things I would assign random numbers to Navy vessels AIS names and change them often. No need to let the BadGuys know that there is a high value target coming into range....

But then again who knows. Might have been 74 - I was going by memory and there were a few ships on that cruise.

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Why would you not think although there not sending ais they are not looking at who is sending it
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Old 04-01-2012, 15:32   #53
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Quote:
Originally Posted by capn_billl

The only difference between an AIS receiver built into a VHF, and a full transceiver would be just 1 circuit to encode and transmit position info from GPS signal. Probably easiest to build into VHF and GPS combo unit, as in the Standard Horizon example you cannot gaurantee the user will plug into GPS.

A user ID unit that plugs into an existing DSC capable VHF for class B transceiver should be on the market soon.........
If this means what I think it means, I am all in.

The vhf/ais receiver with 5 inch (or so) display and nmea output for second/separate is attractive as a "merged" unit. When the vhf incorporates full ais transceiver function I may find it irresistable...
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Old 04-01-2012, 16:31   #54
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Re: AIS experience offshore?

Quote:
Originally Posted by DotDun View Post
Please qualify the statement.

Might be true if you are only interested in seeing <1% of the floating objects on the water.
Well, I guess my statement is an opinion. For less than $200, with AIS one can see all commercial shipping and be alerted to ships that will be inside a definable safety zone and how soon they will be there. If the ship makes a 5* course correction 15 miles out, it tells you this and alerts you that the ship will now stay outside your safety zone. The AIS tells you the course, direction and speed of these ships and where they are headed. It also gives you their name and mmsi number so you can call them if needed.

And all of this with a quick glance.

We mainly use our $5,000 radar at night for the same function, only we spend a lot more time setting EBL's and determining their course, direction, speed and if they will come inside our safety zone and when it might happen. And if they begin to make a small course correction a long distance away to avoid us, it is usually 15-20 minutes before this becomes apparent on the radar plot. If I need to contact a ship, my only recourse is to dial around the channels calling out "ship at so-and-so position..."

Our new radar should be more helpful, as it has ARPA functionality, but I know we will still mainly use the AIS because the information is so concisely presented.

So, in my opinion, the AIS gives a lot more cost/benefit than radar.

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Old 04-01-2012, 17:16   #55
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Re: AIS experience offshore?

We instaled a Watchmate 850 last year. Class B transponder and A B reciever. So far, all USCG on the Great Lakes are sending and all commercial fishermen we have seen. Also, the entire fleet of Tall Ships. Any vessel required to have one (Class A) has it on. The display is on the bridge over the companion way. Power use is only 3 watts and it doesn't care what voltage you feed it. It has an integral GPS antenna. It runs anchor watch and plots your position all night long as a cloud of specks. If you pop up to see it, there is no doubt where you have been. NMEA 183 linked to my VHF and RAM as hoted above. I have it installed as stand alone so nothing else needs to be on for it to work. I think it is better for big lake crossing in fog than radar. Almost no small boats stray outside of a couple miles in the fog. This is the most dirt simple piece of electronics I have ever used. You will not need the instructions. Just follow the live menue at the right. In the photo you see it on anchor watch. The boat is the arrow above the anchor. You can see the swarm of dots "where we were". The other two 'boats' are bugs. Only one note - it is not loud enough but you can add an external claxton to wake you.

This unit also has many filtering options so you can have it ignore all anchored vessels and all vessels headed away or not crossing withing your defined circle. Nice in very busy harbors.
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Old 04-01-2012, 17:18   #56
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Re: AIS experience offshore?

Another thing, I've never seen a ship change course because I painted it with my radar, I've seen many do so on receipt of my AIS transponder data!

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Old 04-01-2012, 17:39   #57
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Re: AIS experience offshore?

For those of you holding out for a VHF with integrated AIS transponder, the AIS Class-B specification requires that the transponder include a built-in GPS receiver (and not just an NMEA GPS input).

This is supposedly required so the "less technically capable" pleasure craft owners won't be able to improperly connect the GPS data. It is also supposed to make it harder to "spoof" your AIS-reported position, although if someone really wants to do that it's easy enough...

Strangely enough, this makes it more likely that we will see a hand-held Class-B transponder / VHF, than a permanently-installed AIS Transponder / VHF. There are already Personal Locator Beacon-type devices that incorporate GPS and AIS transmitters.
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Old 04-01-2012, 18:28   #58
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Re: AIS experience offshore?

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I saw "Navy vessel XX" via AIS from my home receiver, and looked them up. Yes, the carrier John C. Stennis, coming home from the Mideast. (Are you sure it wasn't vessel 74?). Anyway, I sent "welcome home" email to the ship's public email address and ended up having a nice (short) email conversation with them.

The military sealift (supply) ships usually send AIS, and around here at least the USGC ships do as well. The U.S. Navy fighting ships hardly ever transmit AIS.

Here's a weird AIS sighting: The SBX-1, a military sea-based X-band radar platform:

These guys were parked about 50 miles offshore of San Francisco for a week, never moving more than a few feet. I saw their AIS signal and had another brief email conversation with them. The were coming from Hawaii, and going to the Aleutians. Last year I saw them in Seattle, getting work done in port.
How did you have a email conversation with them? AIS give lots of info, but not email addresses. I am very curious as to how you managed it?
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Old 04-01-2012, 19:00   #59
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Re: AIS experience offshore?

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How did you have a email conversation with them? AIS give lots of info, but not email addresses. I am very curious as to how you managed it?
Bazzer
Easy: I was at home on the computer, with data from my AIS receiver in one window, and an internet browser in another. I Googled the vessel name -- as I recall it was SBX1 -- and found a website that included an email address for the Information Officer (or someone like that). I sent a friendly email, and it went to someone aboard the SBX-1.

This was an AIS target that was behaving quite strangely. I noticed it one day, about 50 miles offshore, with another vessel right alongside. The other vessel then headed into San Francisco Bay, stayed for a day, then went back out to SBX-1. This repeated several times during the week. What was going on??? SBX-1 hadn't moved more than a few feet this entire time. Was this drug trafficking? Why would a smuggler be stupid enough to be running AIS???

I tracked down the support vessel using Google, and possibly the MMSI database search tools, and put the pieces together.

I considered sailing out to take a look in person, but decided it would be prudent to leave them alone. I didn't mention this to any of my on-line AIS buddies until SBX-1 was long-gone.
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Old 04-01-2012, 19:13   #60
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Re: AIS experience offshore?

Quote:
Originally Posted by Paul Elliott View Post
Easy: I was at home on the computer, with data from my AIS receiver in one window, and an internet browser in another. I Googled the vessel name -- as I recall it was SBX1 -- and found a website that included an email address for the Information Officer (or someone like that). I sent a friendly email, and it went to someone aboard the SBX-1.

This was an AIS target that was behaving quite strangely. I noticed it one day, about 50 miles offshore, with another vessel right alongside. The other vessel then headed into San Francisco Bay, stayed for a day, then went back out to SBX-1. This repeated several times during the week. What was going on??? SBX-1 hadn't moved more than a few feet this entire time. Was this drug trafficking? Why would a smuggler be stupid enough to be running AIS???

I tracked down the support vessel using Google, and possibly the MMSI database search tools, and put the pieces together.

I considered sailing out to take a look in person, but decided it would be prudent to leave them alone. I didn't mention this to any of my on-line AIS buddies until SBX-1 was long-gone.
You have online AIS buddies?
This is more than enough reason for me to not transmit AIS. Too many strangers watching...
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