Closest Point of Approach

[Cigatoo]

We were crossing Lake Ontario in an extremely heavy rain, the worst I have ever been underway in. Our 4kw radar was in white out mode due to the rain. There were 2 freighters crossing our course and the only way I knew they were there was the AIS. I could see them on the plotter but I couldn’t see anything on the radar. One obviously would cross well ahead of us. The other was on a collision course with us. We were stand on and they were give way. As I was reaching for the mic the freighter called us by name. I don’t know if he was able to see us on radar or not but he could see us via AIS since he knew our name. He stated his intention to turn to cross behind us. Without AIS I would have not known that he was there and maybe he would have not known we were there either. His radar may have been able to punch through the rain, I don’t know. But this one time paid for the AIS.

Exactly my point. Radar is great but more is better.

 

[Cigatoo]

And that trusty VHF comes in pretty handy. Always scanning 16/13 when in poor visibility.

 

[twistedtree]

Sometimes it takes a while for our system to resolve an MMSI into a name. Dunno why... Maybe the MMSI transmits every time, name only every other sometimes?

-Chris

Yes, that's exactly how it works. You "dynamic" data is transmitted regularly updating you position, COG, and SOG. And "static" data is transmitted much less frequently, so the boat's name, dimensions, call sign, etc. can take a while after first contact to populate.


The only danger with AIS is not understanding what it's telling you, and what it's not telling you. Every tool has it's limitations, and knowing them is just as important as knowing the tools strengths.

 

[Sailor of Fortune]

You can "what if" to death... the prudent mariner uses all available aids to navigation. Electronic, visual,paper etc. Anybody with more than a weeks experience can come up with a "near miss" he did this, he should have done that, I am right , he is wrong etc.... We all learn by experience and our mistakes. The Rules of the road are the bible but even they say you should give way...

 

[DDW]

The lie that radar tells is one of omission. You can't always see everything with it, and in some conditions you can't see anything with it. A recently transmitted AIS report is both more accurate and more informative than radar. The mistake in using either is assuming they contain everything you need to know.

 

[Wayfarer]

I don’t know if he was able to see us on radar or not but he could see us via AIS since he knew our name. He stated his intention to turn to cross behind us. Without AIS I would have not known that he was there and maybe he would have not known we were there either. His radar may have been able to punch through the rain, I don’t know. But this one time paid for the AIS.

I've had my radar washed out by rain many times on the ship. With a bit of fiddling, you can clear the picture up, but with a smaller target like any of our boats, it's entirely possible that his radar never picked you up. That's a great time to have AIS.

 

[caltexflanc]

We were crossing Lake Ontario in an extremely heavy rain, the worst I have ever been underway in. Our 4kw radar was in white out mode due to the rain. There were 2 freighters crossing our course and the only way I knew they were there was the AIS. I could see them on the plotter but I couldn’t see anything on the radar. One obviously would cross well ahead of us. The other was on a collision course with us. We were stand on and they were give way. As I was reaching for the mic the freighter called us by name. I don’t know if he was able to see us on radar or not but he could see us via AIS since he knew our name. He stated his intention to turn to cross behind us. Without AIS I would have not known that he was there and maybe he would have not known we were there either. His radar may have been able to punch through the rain, I don’t know. But this one time paid for the AIS.

You have to learn how to tune your radar in heavy rain. I'm sorry for the tone, but that's just no excuse. And yes, I understand you are talking about very heavy rain. What about boats without AIS? How you going to find them?

 

[dhays]

You have to learn how to tune your radar in heavy rain. I'm sorry for the tone, but that's just no excuse. And yes, I understand you are talking about very heavy rain. What about boats without AIS? How you going to find them?

Braille?

 

[Comodave]

You have to learn how to tune your radar in heavy rain. I'm sorry for the tone, but that's just no excuse. And yes, I understand you are talking about very heavy rain. What about boats without AIS? How you going to find them?

I know how to tune my radar. It could not punch through the rain, did I mention that I don’t know if I had ever been in that heavy of a rain. Sometimes conditions are beyond not only your control but beyond the radars capability. And I was not making an excuse, just stating a fact.

 

[ranger58sb]

The lie that radar tells is one of omission. You can't always see everything with it, and in some conditions you can't see anything with it.

A recently transmitted AIS report is both more accurate and more informative than radar. The mistake in using either is assuming they contain everything you need to know.

Sure, but that kind of "lie" applies to AIS as well. If 99% of boats nearby don't transmit AIS...

-Chris

 

[rslifkin]

Neither system is going to magically tell you everything that's going around you, but it'll tell you more than you'd know without it.

 

[sunchaser]

Our AIS tracks ships and ferries quite nicely around the hundreds of PNW blind mountains where radar can't see. Wouldn't be without when covering the waters around Active Pass and Haro Strait. At 1/10th to 1/20th the cost of a quality radar it seems a no brainer.

 

[psneeld]

My experience with accident investigations, its often what you don't know that gets you.


So it's not the absolute value of info...it's what works best for what you do.


Yes .....more info is better to the degree it's not distracting (which we see in recreational boating a lot)....over reliance on tech can actually increase danger versus reduce it....also seen a lot in recreational boating.

 

[dhays]

Our AIS tracks ships and ferries quite nicely around the hundreds of PNW blind mountains where radar can't see. Wouldn't be without when covering the waters around Active Pass and Haro Strait. At 1/10th to 1/20th the cost of a quality radar it seems a no brainer.

I agree that for the commercial fast movers it is really nice to see them coming. Rich Passage in WA is a place where I really like being able to tell when the ferries are coming through long before I or my radar can see them. Being Class A, the information is very reliable.

 

[Gulf Comanche]

I didn’t use the radar on my sailboat unless there were visibility issues; running at night, fog, heavy rain, etc... Being out in the cockpit, open to the elements, I always had very good situational awareness of other boats. However, over the past couple years I am finding that I am using the radar most of the time now. Sitting in the pilothouse I’m not as aware of traffic coming from behind me. The radar is really handy for that. I don’t use the alarms because there is usually so much traffic that it would always be going off. However I do select targets frequently and use that information.

I do love the AIS though. I only have a receiver but want a transceiver some day.

In the rivers I run to get to open water the radar is my rear view mirror.

 

[rgano]

I have run an AIS receive-only for a number of years mostly just in bays and rivers. When I had a trawler running the winding rivers, especially the Tenn-Tom, it was nice to see the tows coming my way around bends which radar could not see. I think if I still had that boat I would install a transponder after the experiences I had with one I installed on a boat I delivered up the rivers. With the transponder, the tows were also aware of my presence both underway and at anchor and sometimes called me before I called them, something which never happens with my receive-only unit.

 

[caltexflanc]

My sentiments as well Rich. But as a reminder, everyone got along just fine before AIS through extensive radio communication, which still exists.

 

[rgano]

My sentiments as well Rich. But as a reminder, everyone got along just fine before AIS through extensive radio communication, which still exists.

It's just so much better with AIS added to the mix.

 

[Jgutten]

I really like the new Raymarine software when it comes to AIS. I've attached a picture of my display showing an AIS buoy and an AIS target approaching. The colored zones are Collision Avoidance Zones.