Tuesday, December 9, 2014

An AIS Receiver Can Save Your Life!

Cruising Old School

While cruising the Caribbean, we really enjoyed sailing through the night. The tranquility is empowering, and the spookiness is exhilarating! Our biggest concern was trying to figure out what the various tankers, freighters and cruise ships were doing. We were cruising "21st Century Old School," with a GPS chartplotter and a VHF. No radar. No AIS. No loud hailer.

One night, while sailing in the Northwest Providence Channel heading to Florida, we encountered a container ship on the horizon. No big deal, we though. We could see the white and red navigation lights, so it was going to pass us on our port side. Just to make sure we were seen by the helmsman, we had a habit of turning on the deck light to illuminate our sails. Now we didn't leave the deck light on - that would ruin our night vision.

After continuing on our course for about 15 minutes, I scanned the horizon again. Now I could see white and GREEN navigation lights! The ship had changed course, and would now pass to our starboard. It was still about 10-12 miles away, so that was not a big deal. We were ghosting along at about 6 or 7 knots. I adjusted our course a few degrees to the left to give us more room.

Another 10 minutes passed and it was time to scan the horizon again. The ship is much closer now, probably 5 or 6 miles, and I could see the white mast light, as well as BOTH RED and GREEN lights! It was heading straight for us!! I turned on every light we had - anchor light, steaming light, deck light, cabin lights and even a flashlight to make us more visible. Then I got on the VHF radio. Calling on channel 16 I called a PAN-PAN with our name, position and heading, and attempted to get in touch with the container ship. Of course, not knowing the name of the vessel, it was like yelling "Hey You" in Times Square. Nothing.

Now it was time to grow concerned. We have a rogue container ship bearing down on us, and we have no way of raising them on the VHF. For all I know English wasn't even spoken on board. I cranked up the engines and turned 90 degrees to the right, heading for deeper water and trying to put some distance between us and the ship. It sure would have been nice to be able to call the ship by name.

Enter Our Hero - Automatic Identification System (AIS)

This where an AIS receiver would have been handy. AIS is a technology that commercial vessels and large yachts use to broadcast their particulars to other vessels using VHF frequencies. The broadcast includes their position, heading, speed, and, importantly, Vessel Name. This would have helped us tremendously with our encounter above. All AIS-equipped vessels in range will be displayed on your chartplotter. The details of each vessel is visible by clicking on the screen icon. If we had known the name of the container ship, we very likely would have been able to have a conversation about their intended course.

One Better - Digital Selective Calling (DSC)

One other key piece of data that is broadcast by commercial vessels and large yachts is their Maritime Mobile Service Identity (MMSI). This key piece of information about a large vessel allows other vessels to call them like a telephone. If your VHF radio has its MMSI number configured, you can use its DSC features to call another vessel directly. Just like calling them on the telephone. Punch their MMSI into your DSC-capable VHF, and you can make a direct call to that vessel. Now that is the way to cruise! With some integrated VHF/Chartplotter systems, you can even make the DSC call with just a few taps on your chartplotter.

Modern technology is wonderful at making cruising safer and more enjoyable. However, there is no substitute for a diligent and watchful captain. Keep your eyes peeled at all times, and operate your boat defensively. Nobody wins in a collision.

Happy cruising,
Tim

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