Radar or AIS to rouse me when in a stupor?

[CarlF]

I find radar guard zones to be close the useless. You can’t set for CPA so you get a huge number of false alarms since most ships entering the guard zone are not a collision risk. And a crossing boat on a collision course may not enter a narrow guard zone until too late (I believe some brands now try to include automatic MARPA acquisition but with the possible exception of Furuno , the MARPA of recreational radars like Garmin and Raymarine is also useless - unable to get speed or direction with sufficiently accuracy and consistency).

AIS - especially with good filters like the Vesper - can be tuned to the situation. At night I set a CPA of two miles to have plenty of time to collect my wits before dealing with a 800ft container ship going 22kts.

The argument that not all boats transmit AIS is a silly argument. That’s like saying you won’t watch for navigation lights because some don’t use them. In US and European waters virtually every ship big enough to worry about running you down is transmitting AIS. It’s required by law over 65ft not to mention career ending insurance and license risk for commercial captains who have an insurance claim while not using AIS.

It’s also stupid today to have an AIS receiver without also transmitting. With large ships it’s just as important that they see you than you see them. They are navigating using AIS CPA and will adjust their course at a great distance to insure a 1 NM CPA or nail on VHF. You can quote “Stand on” and “Give way” to your heart’s content but this is how large cargo ships operate today at sea.

Having said that, I use radar along with AIS but not Radar guard zones. I take a careful look at the radar every 15 minutes (have an alarm set to make sure Imdo)

[thomm225]

An AIS Transponder is much better as far as power requirements unless you already have a huge battery bank to power a transmitting radar for most of the day.

[smj]

Originally Posted by CarlF

I find radar guard zones to be close the useless. You can’t set for CPA so you get a huge number of false alarms since most ships entering the guard zone are not a collision risk. And a crossing boat on a collision course may not enter a narrow guard zone until too late (I believe some brands now try to include automatic MARPA acquisition but with the possible exception of Furuno , the MARPA of recreational radars like Garmin and Raymarine is also useless - unable to get speed or direction with sufficiently accuracy and consistency).



AIS - especially with good filters like the Vesper - can be tuned to the situation. At night I set a CPA of two miles to have plenty of time to collect my wits before dealing with a 800ft container ship going 22kts.



The argument that not all boats transmit AIS is a silly argument. That’s like saying you won’t watch for navigation lights because some don’t use them. In US and European waters virtually every ship big enough to worry about running you down is transmitting AIS. It’s required by law over 65ft not to mention career ending insurance and license risk for commercial captains who have an insurance claim while not using AIS.



It’s also stupid today to have an AIS receiver without also transmitting. With large ships it’s just as important that they see you than you see them. They are navigating using AIS CPA and will adjust their course at a great distance to insure a 1 NM CPA or nail on VHF. You can quote “Stand on” and “Give way” to your heart’s content but this is how large cargo ships operate today at sea.



Having said that, I use radar along with AIS but not Radar guard zones. I take a careful look at the radar every 15 minutes (have an alarm set to make sure Imdo)

Not all boats do transmit AIS, and a radar will pick up a boat not transmitting AIS better than an AIS receiver?
Do large ships keep an eye on all AIS signals, or do they possibly filter out the smaller boats?
Either way, it’s stupid to rely on only your electronics as they are just another tool that can completely distract you from keeping a good watch.

[ranger58sb]

Originally Posted by Chotu

Crap. I definitely need a second opinion on this post. Can other people please chime in with what they think about it?

Originally Posted by SV_Sweet_Ruca

It does not always receive a "bounce". The reason is waves.

Radar can be ineffective in offshore conditions. It will surely pick up a cargo ship, but don't expect it to consistently pick up a 20ft fishing boat offshore in a blow.

No, you're still on the right track. You're playing a probabilities game, and stacking the odds at least a bit more favorably in your direction.

He's right, your radar might not pick up small (-ish) stuff in all conditions, but the odds of a 20' fishing boat (or a kayak or whatever) transmitting an AIS signal are in the region of slim to zip.

You'll be able to tell when conditions suggest your radar might be challenged... so you'll recognize when you need to pay more attention yourself.

Add nothing, you're always on your own. Add radar, you're better off, at least most of the time. Add AIS when you can, and then you'll have that input too. (Around here that'd mean you'll see something like 1% more boats with AIS -- the other 99% don't transmit.)

-Chris

[wholybee]

I am going to be the dissenting position here and say, "it depends."

AIS has the advantages that it transmits other data with your position. Ship name, type of ship, SOG and COG. You are a sailboat. You want M/V to know that ASAP. And you see all that information as well. Once you are out of coastal waters and in the ocean, you will very rarely, if ever, see a vessel without AIS. Once in a while in some areas you will see a Chinese fishing vessel without. They are so slow moving and so well lit, that even if you only look outside every 30 minutes, you will see them many miles away. More times than I can count, a cargo ship has contacted me by name 6-10 miles away to arrange a crossing, let me know they see me, or whatever. They couldn't do that if I only had radar. Based on this, I think that AIS is *Mandatory* with or without radar, with or without being single handed. There are not many cases, certainly among "cruisers" where I could justify not having AIS.

Radar has the distinct advantage that it sees objects and ships that don't have AIS. With AIS alone, you could hit something that radar would have seen. If you are in an area with a higher collision risk, particularly with fog, coastwise with lots of small fishing vessels without AIS, then radar becomes mandatory. In areas with little fog, when sailing during the day, or if crewed at night, radar is not mandatory. So, radar is not always mandatory, where I think AIS is always mandatory.

Compare the photos on the Quantum website with those I am attaching. Note that with AIS dashed lines are drawn between me and other vessels showing the "closest point of approach", with vessels that might be a collision risk are red, and how many vessels and how clearly, they are shown, that they are anchored, etc. With radar, you see large smears where I see individual ships. I can see which are anchored, which are moving. I can see ships that are behind walls or obstructions that I need to wait for before I make my entry into the port. I would have been terrified to go through busy ports without this detail. Radar would have been no help here, day or night.

Edit:
Also. All of the arguments for Radar are "what-if" scenarios. AIS would be used every time you get in the boat. Radar, only in certain situations.

[singlespeed]

Radar and a permanent radar reflector. Lots vessels running around either without AIS or AIS not transmiting, especially so in areas known to be transited by smugglers of people or drugs and waters. Not sure the value of more than a AIS receiver, as a couple of years using a transmitter/receiver, I never can with certainty attribute any calls to my vessel because the calling vessels never used my vessel's name. It's always "unidentified vessel" request.

[Mike OReilly]

Late to the party here, but again I'll echo having radar as your number one choice -- assuming you need to make a choice, which really doesn't make much sense. The right answer is to have both. Radar is by far the more expensive and complicated tool. AIS is easy, and AIS-recieve-only is child's play. So there's really no reason to make it an either-or choice.

For those who claim AIS is the king, you clearly don't cruise in my waters. The vast majority of vessels are not transmitting AIS signals. You'd be a fool to make that your primary collision avoidance tool.

Perhaps in some areas AIS is superior. It's certainly easier to use, and more in tune with our screen-driven worlds. In areas where all vessels are transmitting, then it might be superior. But outside the highly developed areas of the world, AIS is only somewhat useful.

[JPA Cate]

Biggest problem with radar alarming will occur when something else is blocking the signal. If you are in a torrential rainfall, or a heavy wet squall [have encountered wind squalls, without rain], the radar displays the drops as targets, like a curtain in front of any large metal objects, like ships, or channel markers or land. Eventually, it will "see" the ship, but it might not see it until it was too close for it to avoid you. The other thing is that in some areas, there are still timber fishing boats. Wood is a lousy radar target.

You would not have that problem with AIS, but radar generally would give you at least 8 n. mi. warning. Not always. Radar is absolutely perfect for being able to tell you how far off land you are, or how far off another boat is. You can learn to estimate their course and speed from the display.

For the short term, I'd suggest you travel in long day hops and rest overnight. It will be better both for your health and for the people you're sharing the water with. Later on, if you keep the boat, add the AIS. Just do remember that the further off the beaten path you go, the smaller the numbers of boats with AIS. [The way our cruising style evolved, we took to letting weather determine when we traveled; and that led to riding the favorable winds as long as they lasted, then duck in and anchor out and wait for the next system. This in turn led us to sail farther offshore where the winds and current were most favorable, which put us out amongst the commercial traffic, and since we've had an AIS transponder, one can see them alter course to avoid us, unless their course already has them going inside us. With their high mounted antennas, they must see us a long ways away. We have picked some of them up at over 50 mi. The failure mode is that sometimes, the ships' AIS may not be turned on, or may have an electronic fault needing repair that developed under way. It is likely that in areas where we have not been, they may not be required to have it operating anyway. Jim and I do a loose 6 on 6 off watch schedule.] I would suggest that you consider taking crew for longer passages. Otherwise you should really study the singlehanding threads. Once out on the ocean, in general there is little congestion outside the commercial shipping routes, and it's possible Boatman 61's sleeping at night rhythm will work for you. One of our long term singlehanded buddies used to eat a watermelon at bedtime. The ensuing bladder pressure woke him at intervals and then he also looked around.



Ann

[El Pinguino]

For me it would depend entirely on where you are sailing. Inshore with a sea running the small craft with no AIS will probably be lost in the sea clutter on your radar so a bit of a no win situation there. Well offshore all you will be coming across is commercial shipping with AIS. I think in the inshore situation you just have to stay awake.

[JPA Cate]

Boy, you got that right, El Ping, those little fishing boats can drive you nuts.

Ann

[Jim Cate]

Chotu, I have no personal experience with late model radars, but CF member Dockhead, with whom I expect you are familiar, has reported very good results with the alarms on his radar. You might ping on him for comments.

Jim

[Statistical]

Radar is a useful and if I had to choose radar or AIS (a dubious requirement) I would choose radar.

However it likely won't work as well you think for your niche purpose that is an eyes off proximity alarm. Either you set the alarm range very high and in a busy seaway are getting alarms left and right or you set it very close and have a dangerously short warning window.

AIS does true collision detection. That is taking the target and you and both of your courses and determine if a close pass occurs. You can limit the alarm to vessels which will pass close to you not just any vessel (to include those with 0% chance of colliding with you) within x nm. Radar at least any civilian radar I have see is a lot more dumb. A blip out there within range trigger alarm.

So with AIS you can get alarms only for true crossing threats and get them far enough out to react before it becomes a high stress situation. Unless something radical has changed in the last couple years you aren't getting that with radar.

Now AIS isn't a complete solution as sadly a lot of boat still don't have it although it is getting better. Offshore most of the big ships the ones who can easily run you down and not even notice has AIS. Do 100% no but ensuring 95%+ see you and you are notified of a near crossing is huge. Running offshore solo without AIS is just penny wise pound foolish to me. Compared to the cost of kitting a bot for offshore use an AIS is a rounding error.

This is specific to your situation (offshore, solo, need "eyes off" alarm): you need to have AIS. Other people in other situations might not but you need it. You should have radar too but you need AIS. It is a numbers game.

[Chotu]

OK. It does look like both are required. I just wish you guys would keep my bills a little lower. Ha ha.

I wasn’t planning on getting any of these electronics. Nothing. I haven’t used them my whole life so I figured I wouldn’t start now.

It’s been a slippery slope since I have been required to get the Raymarine MFD in order to have my auto pilot work properly. None of this was in the budget.

[Chotu]

Here are a couple of the features with the Raymarine quantum 2 that are on the website but I think people probably didn’t click through.


* The Quantum 2 also features fully automatic target acquisition and tracking. Configure custom safety or alarm zones and be alerted to new radar contacts entering the zone. Quantum 2 can begin tracking those contacts automatically, calculating their course, speed, closest point of approach and more. You’ll be alerted to dangerous contacts with audible alerts and easy to understand on-screen graphics.

* Quantum 2 also features Raymarine’s new True Trails target history display. The True Trails features enables you to see a historical “wake” behind every moving contact. This additional information makes it even easier to interpret the motion of other vessels, and make smart maneuvering decisions to pass safely.

* DOPPLER TARGET PROCESSING
Doppler radar is tuned specifically to detect the radar echo frequency shift returned by moving vs. stationary targets.
Quantum 2 then uniquely color codes moving targets to indicate whether they are getting closer, or moving away.
Inbound targets are colored red.
Outbound targets are colored green.
Color coded targets make it simple to pick out moving traffic from other stationary targets like land, navigation aids or stopped/anchored vessels.


So that first paragraph sounds a lot like what I’m trying to do.

[Mike OReilly]

Originally Posted by Chotu

I wasn’t planning on getting any of these electronics. Nothing. I haven’t used them my whole life so I figured I wouldn’t start now.

This is a good point. Your primary collision avoidance tool is the lump of grey and white matter between your ears. I think the best way to avoid bumping into things is to be smart about where and how one travels. AIS and radar are a nice additional tool, but the best way to avoid collision is to make smart choices.