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AIS and How I Use It on SleepyC Update AIS info

 
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hardee



Joined: 30 Oct 2006
Posts: 12632
City/Region: Sequim
State or Province: WA
C-Dory Year: 2005
C-Dory Model: 22 Cruiser
Vessel Name: Sleepy-C
Photos: SleepyC
PostPosted: Fri Nov 19, 2021 10:08 pm    Post subject: AIS and How I Use It on SleepyC Update AIS info Reply with quote

AIS and How I Use It on SleepyC Update AIS info
Nov 19, 2021

Class A And Class B Automatic Identification System make up the (AIS).

I was recently asked this question:

Quote:
“Harvey is it the receive AIS function you use the most? Any tips on how you use it? I have a vhf with AIS receive I’m planning to install and tie into my Lowrance.”


It was on this thread at page 271 (in a discussion from where DayBreak had a new AIS and Auto Pilot installed)
SO WHAT DID YOU DO WITH OR ON YOUR C-DORY TODAY?? page 271
http://www.c-brats.com/viewtopic.php?t=244&start=4050

Here is my answer:

The AIS is turned on along with the other electronics, right after the engines are started so that it is both transmitting my position and receiving txs from any vessels inside my reception circle setting. (That size varies from 2 to 12 miles depending on where I am and where I am going.) The AIS data is sent to my RayMarine C-120 chart plotter so I have each AIS vessel showing its position on my plotter in relation to where I am. The vessel symbol is a triangle so I can tell instantly what general direction that vessel is heading. Anything in front of me and pointed towards me get the same interrogation. It takes about 1 second to put my curser on that target and another couple seconds and I have the primary info I need for collision avoidance, CPA and TCPA (Closest Point of Approach, and Time to CPA). My active AIS is a WatchMate Vision by VesperMarine and has a separate monitor, but I do most of my AIS activity on the C-120. I start with the closest triangle and then work my way out. Then I look at anything beside me and then behind, looking for conflict, a vessel faster than I am going and with a CPA or TCPA that is concerning. Initially this process might take 1 minute. This is usually done after I turn to my intended heading and am at my planned speed. That way the CPA and TCPA are most accurate. (And yes, the radar is on BECAUSE not every boat on the water is transmitting an AIS signal.

Often times I am crossing, or at least, out in the Strait of Juan de Fuca where there are commercial traffic lanes, established and monitored by Seattle Traffic. I listen to them on their VFH channel (5. 11 or 14) for status updates on their traffic. I also widen the AIS reception to 12 miles when crossing, and “interrogate” any triangles heading towards me or my route in crossing. The big, ocean-going ships are running somewhere between 15 to 20 knots and sometimes more. There are some fast cat ferries in the area that do 35 knots. These are where the fast response of the AIS shines. In seconds I know “how close” and “how soon” any of these vessels will be a concern and I can plan accordingly. Depending on the proximity, direction (based on where they are and the destination stated on the AIS, and relation to me) I may call them (vhf 13 or on the Traffic channel) and get several things. 1.Do the see me on AIS, Radar, and visually? 2.Are they maintaining speed and course, or have a turn planned? 3.If a turn, how soon, and which direction? Once I have those answers, I can decide my crossing plan and give that to them. I don’t cross in front in less than 2 miles, and behind in less than one mile, so I give them that info and ask if they are agreeable. If I am crossing in more than 5 miles out, I wouldn’t likely do the VHF call unless it is foggy and visibility is limited, then I call and confirm that they see me on AIS and radar and that they are maintaining course and speed.

This is how I use the AIS on SleepyC, and it has worked well for me.
It is my firm belief the AIS is one of the great Safety devices available to us as recreational boaters that participate in an activity in the same areas and sometimes in close proximity to very large commercial vessels, akin to flying general aviation aircraft into the air and sharing that space with commercial jet traffic, albeit maybe not at the same pace. A 747 tangles with a Piper Cub might hardly feel the bump. A CD-22 crossways on the bulb of a 900-foot Container hauler, won’t even know it’s there until it is tied at the terminal. It behooves us to share space and technique for safety in an effort to keep things moving as easily as possible and make sure everyone returns home safely.

These are my favorite links to AIS info on C-BRATS.

Yes, some of them are older but there is still some very good, helpful and useable information on these threads.

Is AIS in the house?
Initial Post: Thu Jan 31, 2008 12:20 am by hardee
http://www.c-brats.com/viewtopic.php?t=8000&highlight=ais+house


AIS transmissions
Initial Post: Sun Dec 20, 2020 11:40 am by colbysmith
http://www.c-brats.com/viewtopic.php?t=29232&highlight=ais+house


New combination VHF radio, AIS receiver/Hailer
Initial Post: Thu Nov 26, 2009 8:08 pm by thataway
http://www.c-brats.com/viewtopic.php?t=12690&highlight=ais+house+electronics


Harvey
SleepyCMoon

There is one AIS triangle near me on the monitor.

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Though in our sleep we are not conscious of our activity or surroundings, we should not, in our wakefulness, be unconscious of our sleep.
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