A couple of years ago I installed an AIS receiver in Sin Tacha, and, connected to my GPS and laptop running Memory Map Navigator, it provides real-time position information on ferry and large shipping traffic. My position is also on my screen, and each target has a 15 minute position vector indicating where it will be at that time. If any of these vectors cross mine, an alarm rings to warn of a possible collision.
As I frequently cross the busy traffic lanes along Juan de Fuca and Haro Straights, I find this little device provides valuable information, allowing me to navigate away from danger involving large ships, towboats, and ferries. Even larger pleasure boats are now using AIS transponders to broadcast their positions. My unit is a receiver only, and does not advise other ships where I am.
However, after an uncomfortably close call in the fog today, I may make the additional investment to let my position be known to others.
We were crossing from Trial Island to Pedder Bay in reduced visibility (about 1/4 mile in the fog) when an unusual number of AIS targets started showing up within a five mile radius. A couple of ships had already passed, but there was also a freighter headed our way and a pilot boat heading toward him, both of which were going to come within a mile of us.
Now, a mile seems a long way off , but when a container ship is traveling at twenty knots, this distance can be covered in three minutes. We watched these tracks unfold for a while, until we felt comfortable both ships would stay well clear of us.
Then, from out of the blue (or the gray!) appeared a long (fast) vector headed right toward us. It was yellow in color, indicating moderate danger ... but still a danger.
The ship was a fast catamaran ferry heading for Seattle. It's normal route was to the north of us, so I waited a while for him to turn ... but he didn't! I tried to hail him on a hand held VHF but the radio was not working properly and I did not feel I had time to reach for the other radio and try again. Instead I did a 180 degree turn and almost immediately the fast vessel responded by also turning, unfortunately in the same direction. I can only assume that he did not see me on his radar until I made my turn. I quickly did another 180 degree turn and we were both clear of danger. If neither of us had turned, a collision might have occurred.
(Click on picture for larger image)
One always analyzes these happenings after the fact, to see what one could have done differently to avoid such excitement. The whole 'drama' happened in seconds and was only visible on my laptop screen. No ship was seen and no noise heard. There was not even a visible wake to support the fact we had narrowly averted a nasty incident in the fog.
What I came up with was that:
1: I should not have assumed the boat would take his usual track,
2: I should not have assumed he saw me on his radar, and
3: I should have contacted him a lot earlier by radio.
These three actions would have changed a white knuckle moment to a 'ho-hum' occurence. It did, however, point out what a great device an AIS receiver is, and that maybe a full transponder would be an even greater asset!
By the way, I have no financial interest in Milltech Marine .... they're just a great outfit to deal with!