AIS, Radar or both?

[sharkwatcher]

We are upgrading the electronics on our boat for sailing from FL to the Bahamas and points south. Which would be better to install: an AIS transciever, a radar or both. I know AIS is on all commercial vessels and becoming more popluar on cruisers. Radar doesn't show everything and takes up a lot of space and electricity. I have a Garmn GPSMAP 3205 chartplotter that is AIS ready, if that matters.

[Stu Jackson]

Originally Posted by sharkwatcher

Radar doesn't show everything

Huh? You might have gotten that backwards.

Both.

[Dockhead]

There has been a lot of discussion on this, and views vary. You will profit from a search through the archives.

In my opinion, radar and AIS are in no ways substitutes for each other. I consider both to be more or less essential for any kind of water sailing">blue water sailing, and I would not leave home without either one.

Radar has many important uses -- navigation and pilotage, collision avoidance, especially in bad visibility, enchanced watchkeeping offshore using guard zones. I would truly feel blind offshore without radar.

AIS enormously improves your collision avoidance process by giving you instant and accurate data about how other vessels are crossing with you, saving you all the plotting and analysis you otherwise have to do, to do collision avoidance well.

Broadcasting AIS has become really important as some ships now don't notice you, if they don't see an AIS target for you. They are required to notice you with or without AIS, but human nature is what it is, and AIS so much simplifies the watchkeeper's work, that some of them just stop using the radar as they should.

Besides AIS and radar, don't forget a good radar reflector, which is also essential on plastic boats, which otherwise don't show up well.

[Dockhead]

Originally Posted by Stu Jackson

Huh? You might have gotten that backwards.

Both.

Yes, it is AIS which doesn't show everything. It only shows those vessels which are broadcasting AIS signals. Doesn't show vessels without AIS, doesn't show rocks, obstacles, weather, landmarks, can't do pilotage with it, etc., etc., etc.

Radar does show everything, but requires more interpretation for purposes of collision avoidance. Theoretically, the MARPA on your radar should give you similar data as AIS does, but in practice it doesn't work so well on small boat radars, and even when it works well, it is far less accurate than AIS.

[Terra Nova]

Originally Posted by Dockhead

...Radar has many important uses -- navigation and pilotage, collision avoidance, especially in bad visibility, enchanced watchkeeping offshore using guard zones...

Add storm avoidance.

OP--radar OR AIS? Come on!

[sharkwatcher]

Thanks for your opinions Dockhead, I wanted opinions, not to wade thru 100 threads, most are several years old. I wanted current opinions. Thanks anyway

[a64pilot]

I'd say Radar first, then AIS, both if you can.

Radar reflector I'm a little confused on, it seems from what I can find out that most do little if anything, the more expensive, fancier ones do the least?
Is there a Radar transponder, that is something that receives a Radar signal and then transmits one to make you more visible?

[sharkwatcher]

I understand that radar reflectors are pretty useless, radar uses a lot of power and can be very inaccurate in inclimate weather and the radome requires a bit of space and special mount and installation. These facts don't make it very attractive.

[a64pilot]

Yeah, Radar sucks, until you can't see, but you maybe can hear boats moving around you, then you would give your first born for one.

[Dockhead]

Originally Posted by a64pilot

I'd say Radar first, then AIS, both if you can.

Radar reflector I'm a little confused on, it seems from what I can find out that most do little if anything, the more expensive, fancier ones do the least?
Is there a Radar transponder, that is something that receives a Radar signal and then transmits one to make you more visible?

Yes, that's called an "active radar reflector", like "Sea Me".

The problem with them is that ships use both S Band and X Band, and only very expensive ones will work on both bands.

They also have radar alarms built in.

In my opinion, this is obsolete once you are broadcasting AIS. I don't have an active radar reflector.

I have a normal passive "catch rain" type, and I know from having checked a few times that my boat shows up reasonably well on radar.

Note that there are radical differences in the performance of radar reflectors. There was a test of them a few years ago in, I believe, Practical Boat Owner -- very, very worth reading before buying one. Some of the smaller ones are practically useless.

A64, if you don't have a radar reflector, I would definitely add it. This by the way is practically the only piece of safety gear required in the UK for boats under a certain size (50'?). That should tell you something about how important it is.

[Stu Jackson]

Originally Posted by sharkwatcher

Thanks for your opinions Dockhead, I wanted opinions, not to wade thru 100 threads, most are several years old. I wanted current opinions. Thanks anyway

I can't tell whether you meant this in a nice way or are just rude. Most of the AIS vs Radar posts are within the past year when technology hasn't much changed. And the concepts haven't changed at all since transceivers became available for recreational boats, since radar for rec boats has been around for a long time. This is NOT a timeliness issue at all.

You also might want to investigate your avatar, which says you have a very short sailboat.

[a64pilot]

Anyone know of a pattern I can get and cut out a reflector?
Its a simple thing, ought to be easy and I would think maybe even be made so it could be taken apart and stowed flat?

An issue is I think a simple corner reflector would need to be maybe 2' in diameter to be very effective.

[Terra Nova]

Google "diy radar reflector." But it's easier to just buy one.

[sailjumanji]

When we upgraded electronics last year in prep for our upcoming cruise, we added both the AIS and the broadband radar. The AIS has been invaluable when traveling on the ICW and dealing with tow boats, ships, etc.

The radar was pulled in service in a period of heavy fog. Good for identifying rocks, pilings, and even a swing bridge when we were fogged in on the ICW with less than 100 ft visibility.

If I had to choose, I would say radar if you are mostly offshore or open water voyages, and/or night passages. If daylight ICW and active shipping areas predominantly, then AIS. But like I said, I got them both.

[wrwakefield]

Originally Posted by sharkwatcher

We are upgrading the electronics on our boat for sailing from FL to the Bahamas and points south. Which would be better to install: an AIS transciever, a radar or both. I know AIS is on all commercial vessels and becoming more popluar on cruisers. Radar doesn't show everything and takes up a lot of space and electricity. I have a Garmn GPSMAP 3205 chartplotter that is AIS ready, if that matters.

Hi Sharkwatcher,

As other very qualified cruisers have already mentioned, for blue water you really need both Aids to Navigation you mention, and that RADAR sees most everything, and AIS sees those who broadcast AIS...

RE: RADAR power consumption: You will find the new 3G and 4G units sip power compared to the magnetron and CRT display units... [Our 4G is on almost all the time, if nothing more than keeping a perimeter alarm or two set...]

For us it is all about seeing and being seen. Therefore RADAR is a must for us in our current cruising waters, and we are always broadcasting on AIS.

We also have a very effective [as reported by other boats and ships] Blipper RADAR reflector mounted high up the main mast to especially help boats without AIS receivers see us...

We constantly remind ourselves [and the occasional guest] that all of these electronics are simply AIDS to navigation... and the more the merrier for us [depth, forward looking SONAR, charts, chart plotters, GPS, AIS, RADAR, binoculars, spot lights, multiple sets of eyes, etc...]

And lets not forget how improved today's Aids are compared to the days of using a sextant [my first time through the coconut milk run...] recreational SAT-NAV [could never afford it] RDF [relied on it transiting the Pacific coast] and LORAN-C [the gospel before GPS...]

I have never found any single AID to Navigation that covers every situation completely- including my own eyes and assessment.

Situational awareness and past experiences conspire to keep me humble...

Cheers!

Bill

PS: When you say things like you aren't willing to read past discussions but are ok with others spending their time aggregating and providing that information for you, it gives the impression that you feel your time is more valuable than everyone else's... I truly doubt that is the message you intended with your statement...