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MarkSF 11-26-2012 02:28 PM

AIS very handy yesterday...foggy on SF Bay
 
We found ourselves, and half a dozen other sailboats, in a 0.5 mile square patch of sunlight surround by fog. Thankfully the AIS showed all the large, fast-moving ferry and ship traffic. There was a ferry doing 40 knots that only became visible 1/3 mile away, which is only 30 seconds at that speed, but we could see it miles away on the AIS and get out of the way. First time I've been really glad I had it.

Made for some great pictures, though!

http://i1326.photobucket.com/albums/...2/P1000029.jpg

MarkofSeaLife 11-26-2012 02:39 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
Great photo.

I think AIS is the greatest safety invention since GPS. It really is marvelous.

One trick I do is definitely a cheat... When going through a cut, channel, shallow or difficult patch, I will watch other boats on AIS and watch their track. AIS tracks ae kept up to an hour on my kit, so once someone has gone through I can steal their track and follow it as closely as I would follow them if I was 200 meters astern.

Another thing I like about tracks is that after a while the looneys who drive ferries and other Harbour craft show that they are on set courses. A Harbour becomes easier to understand.

Here is New York after a few miinutes. AIS lets you see the regular routes

http://ourlifeatsea.com/temp/tempny.jpg



Here you can see a good set up give you a very long range!
http://ourlifeatsea.com/temp/ais.jpg
Those range rings are 10nm each. So the second is 20nms from my boat... Its not always this good, especially in bad weather, but you know its working well whene you see this far.

MarkSF 11-26-2012 04:24 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
I've never panned right out to see what my range is... must try it next time I'm on the boat. I do think the OpenCPN implementation is much better than Lowrance's - but still, it does the job. I believe Garmin's is better too.

BarryL 11-26-2012 05:29 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
Hello,

I have the Standard Horizon VHF radio with AIS display and it is very useful. However, there are many fast moving, relatively large boats that don't transmit AIS. So, while it is a useful tool, it doesn't replace RADAR, and you still must practice good seamanship when in limited visibility (as I am sure you all do).

I am amazed at how fast some boats go when you can't see more than 1 minute ahead.


Barry

Mico 11-26-2012 05:34 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
We have the same set up but also use a multiplexer to integrate the AIS output of the Standard Horizon onto our Raymarine Chartplotter/radar.

Works a treat

MarkofSeaLife 11-26-2012 06:54 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
Quote:

Originally Posted by BarryL (Post 953469)
Hello,

I have the Standard Horizon VHF radio with AIS display and it is very useful. However, there are many fast moving, relatively large boats that don't transmit AIS. So, while it is a useful tool, it doesn't replace RADAR, and you still must practice good seamanship when in limited visibility (as I am sure you all do).

I am amazed at how fast some boats go when you can't see more than 1 minute ahead.


Barry

Hi Barry,

I haven't seen one of these boats without AIS. Even naval ships use it. Mind you I've only had it on in the Caribbean, Bahamas and the USA I am sure there are placs where it's not used as much.

http://ourlifeatsea.com/temp/navy.jpg

jrd22 11-26-2012 08:41 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
A lot of commercial fishing boats do not use AIS and almost no recreational fishing boats, as well as most smaller high speed pleasure boats. AIS is not a substitute for radar, although it's better than nothing.

MarkofSeaLife 11-26-2012 09:02 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
Hate to sound disagreeable, but most fishing boats do that I have seen. Game fishing boats don't, but trawlers etc usually do. In the Caribbean and Bahamas he small ones don't, but hey are not going to sink a yacht.


http://ourlifeatsea.com/temp/fishing.JPG
By the way, without AIS I would never have worked out what these two were doing!



And even navy ships...

http://ourlifeatsea.com/temp/navyshipais.JPG

MarkofSeaLife 11-27-2012 08:31 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
In New Zealand they have started to use AIS as remote navigational markers in places they can't put a buoy...
The transmitter is 4 miles away from the place it appears to be on AIS receivers.

Quote:


Using our core AIS technology Vesper Marine has deployed a Virtual Aid to Navigation at the entrance to Doubtful Sound, a fjord in New Zealand’s South Island.

The 80 cruise ships entering and exiting the beautiful Doubtful Sound each summer need to be able to identify a very dangerous underwater obstacle known as Tarapunga Rock. This rock lies just below the surface, close to the entrance to Doubtful Sound. In the past an isolated danger buoy had been moored at the rock’s location; however as the swell could exceed 7 metres at times the buoy broke up and had to be removed.

Vesper Marine provided a Virtual Aid to Navigation system that enables proactive electronic visibility of Tarapunga Rock for all vessels using AIS. A Virtual Aid to Navigation (VAtoN) is created by sending a signal from one location (point A) that marks a remote point (point B). This virtual mark, point B, is displayed as a navigational hazard on a ship’s chart plotter, AIS display or other receiving equipment when within range of the transmitting equipment installed at point A. A ship’s onboard equipment is also able to alert crews if they are on a collision course with the marked navigational hazard.

The VAtoN system was installed at an existing navigation light stationed on nearby Secretary Island. The location of this light is so remote it can only be accessed by helicopter and has to be solar powered.

Despite the remoteness and rugged landscape the installation is proving to be successful and it is achieving good coverage. Ships entering Doubtful Sound can now identify Tarapunga Rock from as far out to sea as 10 nautical miles (nm).

This has been a fantastic project to work on and the ease and relative low cost of deployment gives us confidence that many more navigational hazards can be marked in this way improving environmental and passenger safety for any coastline.

newsletter2012

jrd22 11-27-2012 10:56 PM

Re: AIS very handy yesterday...foggy on SF Bay
 
I'm not negating the value of AIS, it's a wonderful tool. In this part of the world (PNW) I don't know that I've ever seen a commercial fish boat broadcasting AIS, the ferries, tankers, and tugs do so that's a help. I'm just saying that it only takes one "invisible" boat to ruin your day if you are in fog, snow, etc without radar. That is why I say AIS is not a substitute for radar.


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