Tag: AIS

AIS for dirt dwellers

As you may know, Lisa and I are now living in Vero Beach with no boat at all. Lisa has a new hobby taking pictures of cruising boats on the ICW as they pass our condo. She posts these pics on Trawler Life so keep an eye out and you may see your boat. To make her “job” a bit easier I set up a simple AIS station that talks to an iPad running TZiBoat. Just like on Privateer, she gets an audible AIS proximity alert and then heads to the window to set up the photo shoot.

It is possible there are others like us who live on the ICW and would also enjoy keeping track of boat traffic so I am posting the set-up I am using. Yes, we are on land but the gear would work equally well as an emergency back-up on a boat for an all up cost of about $210.

The heart of the system id the AIS receiver from Quark Electronics.

My setup has the black box plugged into a USP power supply and a handmade VHF antenna connected via a short BNC cable (Amazon $8). The VHF dipole is just two pieces of inner core from a piece of coax about 16.7 ” each which works well at 162 MHz. The two dipoles join at a connector (Amazon $6 for 2).

The antenna itself is taped to the plastic molding between two panes of glass on the inside of the exterior wall facing the ICW and gets at least partial coverage of the waterway. Our windows are impact rated and UV tinted so are not good conductors. With this set-up, our range is between 2-3 miles. It would be better if I could lead the antenna outdoors, but no easy way to do that.

Here is a screen shot from the iPad connected to the AIS via wifi, with the AIS in station mode on our home LAN. The big RED boat (i wish) is us. The GREEN boat is anchored, the RED boat (Island Fever II) is tripping the AIS proximity alarm and the ORANGE boat info is being received from the TIMEZERO cloud data server over the internet. Note that RED and GREEN signals are near real time but the ORANGE boat signal came from our AIS receiver as a node in the crowd that fed the server. Since the ORANGE boat is now out of our range the signal will time degrade and soon disappear.

At installation one has the choice of setting the AIS receiver in either ad hoc mode ( wired or wireless link direct to your device) or in station mode ( as a node on your local LAN). In station mode, when using capable nav software such as TZiBoat the system acts like a virtual AIS ground station feeding the TIMEZERO cloud server. Other systems, such as Predict Wing and AquaMap perform this integration in a similar fashion.

Not quite the same as being aboard, but then when I now hear the AIS proximity alarm I don’t need to run to the bridge to take evasive action!

AIS Surprise

We took Privateer out today just to check all the systems after a 2000 hour service and a change of all her oils and fluids. All that went fine.

The area just north of Newport can be pretty crowded so occasionally someone shows up near us that I didnt see coming. In the picture below you can see Big Blue on AIS coming by. She is a 45′ cabin cruiser doing 25 knots.

Big Blue comes by on our port

So I look out the side and see nothing. I get up and go to the door, nothing. Then a minute later she disappears from the screen as well. I search the screen and she reappears about a mile north, where she really is.

My assumption is, there was a malfunction in either her transmission or my reception. More likely her transmission. I have seen AIS return for boats showing them going backwards or sideways, a transmission error that I could sort of comprehend, but this is the first time I have ever seen a boat displaced by more than a mile. The ramifications are quite disturbing.