Monday, August 29, 2011

Another iPhone app you need

A while back, we were in a position that required us to traverse Puget Sound from Port Madison to Shilshole in heavy fog.  (Now, I guess I should examine that word "required" more closely, but that's a story for another time).

Puget Sound has a lot of shipping traffic, and an active and professionally run VTS system.  And we have radar on Eolian.  So I was not particularly worried...  focused and intense, yes, but not really worried.

As we started across, I notified VTS giving our speed and that we were going to be crossing the lanes.  They, in turn notified us of shipping in the area.  It looked good for us - a northbound freighter would be past us before we got to the northbound side of the Sound, and a southbound freighter would pass behind us as we entered the northbound lanes.

But just for grins, I fired up my iPhone and ran the "Ship Finder" AIS app.  This app does not actually have a receiver in it - it takes advantage of information on the Internet somehow (don't ask me how it works).  Sure enough, there were our two freighters, with their courses and speed vectors shown.  And their names.

About the time we entered the separation zone (the "median" between the traffic lanes, if you will), a problem developed.  We heard Manolo (the southbound freighter) complaining of a whole bunch of fishing boats out in the traffic lanes a couple of miles to the north of us, and then he said that he might have to veer into the northbound lanes to clear them.

I watched as Manolo's vector on the AIS display swung until it pointed right at us!  Crap.  The AIS app showed we were clearly now on a collision course, and given our relative speeds, it was going to be difficult for us to get out of his way on any course.  So I contacted Manolo directly on VHF-13, and told him of our predicament, and advised that we were making a 180 degree turn and heading back west toward the southbound lanes (on what would be a collision course if had stayed in the southbound lanes) to try to get out of his path; he acknowledged.

Now came a period of tense waiting, completely blind in the fog.

Eventually, Manolo contacted us and advised that he was past the offending fishing boats and was returning to the southbound lane; I acknowledged and returned to our eastbound course. 

In the fog, we never saw Manolo.

Oh sure, he was visible on the radar display, but that display does not show course or speed, only relative position.  It was the AIS that made obvious what was happening.  If you already have an AIS receiver onboard, you already know this.  But if you don't, then I strongly recommend you get the Ship Finder app (there's a free version - that's what I have).


steve said...

I use a similar app on my android, but CapRR had a pretty damning report last week on these apps, that they may indeed by many minutes or even an hour out of date, as far as showing current position of these boats goes. So, great app, used it myself going through the san juans in the fog, but always use with a large grain of salt.....

Why your AIS app isn’t approved for navigation
By CaptRR on Aug 23 2011

bob said...

Steve -

Indeed, I have noticed some lags. Nevertheless, this was an extremely useful tool in our situation.

Obviously it would be far better to have a full-featured AIS receiver (not a computer program running on your laptop) on board. But that costs real money. If you already have an iPhone, then there is *no reason at all* not to have this app on it.

And of course, one should never put all his navigational eggs in a single basket, right? (GPS anyone?)


David Geller said...

You can also view AIS traffic online through your web browser - on your iPhone and other mobile devices.

bob said...

David -

Thanks for the pointer to the web AIS page! It appears that this is sponsored by the same folks who do the iPhone app, and that it uses the same data. I cannot recommend it for use on the iPhone tho - the actual map occupies less than 25% of the screen. I do like all the explanation provided and the seconds to refresh that are shown tho...


Tim Robison said...

While the internet apps are useful, our investment in Class B ais has been invaluable. We know we are visible to the commercial, fishing, and some recreational vessels around us, and we can see them. If you don't want to put to the bucks them get a receive only unit. In my view and experience so far AIS is more important than radar.

AIS data is displayed on our chart plotter at the helm, using Maxsea TZ on the computer, and I have a wireless connection to the iPad -

We can be seen on at

Add us to your fleet once you sign up!!

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