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Old 22-05-2018, 14:46   #1
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Collision Avoidance

I am considering to use an AIS transponder (Vesper XB8000) and passive radar reflectors in my small cruising sail boat.

Radar AND AIS would be the ultimate solution but with the radar reflectors and an AIS transponder, my thinking goes like this.

If I have AIS, anyone who has AIS will be able to see me and I will see them. With the reflectors anyone with radar should be able to see me and take defensive action. If they ONLY have radar, I won't be able to see them and will need to depend on their defensive measures. Given all this, if they don't have either radar or AIS, they shouldn't be out at night or in the fog.

For the moment, this covers a lot of bases using both AIS and radar reflectors and it also fits my budget. Question...

Would anyone insist upon having both (I.e. Radar and AIS) ? If so, why since being on the water in adverse weather or at night is always a risk even given all the equipment and operational watch and awareness. Again, the only thing I won't see are targets who ONLY have radar. Also, if they've got radar they most likely have AIS.
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Old 22-05-2018, 15:08   #2
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Re: Collision Avoidance

Good luck avoiding fishing boats... who won’t be looking out for you because they’re too busy catching fish and who frequently have their AIS turned off in order to not give away their position.
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Old 22-05-2018, 15:19   #3
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Re: Collision Avoidance

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Given all this, if they don't have either radar or AIS, they shouldn't be out at night or in the fog.
Lots of boats out at night and in the fog without radar or AIS, mine included.
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Old 22-05-2018, 15:36   #4
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Re: Collision Avoidance

also there are boats out at night in the fog without radar or ais and also no running lights.
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Old 22-05-2018, 15:37   #5
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Re: Collision Avoidance

IMO, Radar is a higher priority than AIS. You can see everything with radar, AIS, only those so equipped.
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Old 22-05-2018, 16:42   #6
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Re: Collision Avoidance

Radar and AIS fulfill somewhat different roles. Radar has a great variety of uses besides collision avoidance, and as DotDun said, it sees everything, and not just what is transmitting.

But AIS is kind of a killer app for collision avoidance -- it gives almost instantaneous and highly accurate calculations of CPA/TCPA etc, and also allows you to identify the vessel, making it far easier to call it if necessary, and reducing the risk of confusing different targets.

So I wouldn't be without both, personally. AIS is now so cheap that it's hard to imagine why anyone would do without it. A good radar set is a lot less expensive than it used to be, but requires some skill to use effectively.

As to radar reflectors -- definitely a good idea, but be aware that many small boat radar reflectors, maybe most of them, are practically useless. Be sure and choose one which actually works.
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Old 22-05-2018, 16:56   #7
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Re: Collision Avoidance

Also, depends upon where you are. In high fog areas you really need radar. But then radar doesn’t see everything. And using it, actively tuning it for best results, puts you in a heads down attitude.

One problem with radar is having confidence you can actually pick up a 20’ wooden skiff at a reasonable distance. So you are going along for a couple of hours with no targets and then something slides by, maybe a skiff or maybe a fishing buoy and now you’ve no confidence in the darn thing. So you start fiddling with it, which means your not looking and paying attention.

I’m not against radar, not at all. Just saying it’s not a panacea.

I’m using my radar more, even in the Carribean. For example when coming into an anchorage at night, I use it to look for anchored boats. You can’t be assured of picking them up, but you can generally make out the edge of the pack. And it helps give some accurate distance measurement, hard to eyeball in the dark.
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Old 22-05-2018, 16:58   #8
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Re: Collision Avoidance

Dockhead has it right...But you are assuming that the other guy is looking! After 11 years, 45,000nm and hundreds and perhaps a 1,000 big ship interactions there has been very little evidence that they monitor the AIS closely. They certainly do not see you on radar in anything but perfect conditions.
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Old 22-05-2018, 17:02   #9
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Re: Collision Avoidance

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Originally Posted by boat_alexandra View Post
also there are boats out at night in the fog without radar or ais and also no running lights.
And in places and under conditions you would not expect. And little open boats. I’ve been suprised a few times.
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Old 22-05-2018, 17:18   #10
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pirate Re: Collision Avoidance

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Originally Posted by Dockhead View Post
Radar and AIS fulfill somewhat different roles. Radar has a great variety of uses besides collision avoidance, and as DotDun said, it sees everything, and not just what is transmitting.

But AIS is kind of a killer app for collision avoidance -- it gives almost instantaneous and highly accurate calculations of CPA/TCPA etc, and also allows you to identify the vessel, making it far easier to call it if necessary, and reducing the risk of confusing different targets.

So I wouldn't be without both, personally. AIS is now so cheap that it's hard to imagine why anyone would do without it. A good radar set is a lot less expensive than it used to be, but requires some skill to use effectively.

As to radar reflectors -- definitely a good idea, but be aware that many small boat radar reflectors, maybe most of them, are practically useless. Be sure and choose one which actually works.
Start a course for USN officer's. .
Best way to find out if your reflectors work..
Cross the English Channel in fog with a 5hp ob..
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Old 22-05-2018, 17:34   #11
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Re: Collision Avoidance

An AIS transponder is such a cost effective piece of nav gear, it gives a lot of situational awareness for you and many vessels around you. If money is tight then AIS is way up.there on the list.
A radar reflector probably does little benefit but is so cheap you should have one.
Radar is a major step up in costs. Certainly adds value and can.be useful for both low visibility situations and.for weather evaluation. I don't see not having Radar as a reason to put off cruising.
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Old 22-05-2018, 17:35   #12
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Re: Collision Avoidance

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Originally Posted by boatman61 View Post
Start a course for USN officer's. .
Best way to find out if your reflectors work..
Cross the English Channel in fog with a 5hp ob..

Ha, ha.

Funnily enough, I popped over to Cherbourg for the weekend a few weeks ago, and damned if there wasn't thick fog until the last hour

I've been across the Channel probably hundreds of times, and this is the first time where the fog didn't burn off by mid-morning.

It was real instrument flying -- I sure was glad to have the radar and AIS going through all that heavy traffic. We were picking our way through ships left and right as usual, but never made visual contact . . .

In those conditions, if you make visual contact -- you're dead
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Old 22-05-2018, 17:39   #13
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Re: Collision Avoidance

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Originally Posted by hpeer View Post
Also, depends upon where you are. In high fog areas you really need radar. But then radar doesnít see everything. And using it, actively tuning it for best results, puts you in a heads down attitude.

One problem with radar is having confidence you can actually pick up a 20í wooden skiff at a reasonable distance. So you are going along for a couple of hours with no targets and then something slides by, maybe a skiff or maybe a fishing buoy and now youíve no confidence in the darn thing. So you start fiddling with it, which means your not looking and paying attention.

Iím not against radar, not at all. Just saying itís not a panacea.

Iím using my radar more, even in the Carribean. For example when coming into an anchorage at night, I use it to look for anchored boats. You canít be assured of picking them up, but you can generally make out the edge of the pack. And it helps give some accurate distance measurement, hard to eyeball in the dark.
Sounds like you need a better radar set. I don't count on seeing fishing floats with mine, but I sure as heck count on seeing boats. I might not see a small open boat until I'm a mile away, but I expect to see it reliably by then, and I would throw away the radar set if I couldn't.

I'm using a Navico 4G set which has different pluses and minuses, but absolutely reliable short range detection is one of the pluses. The big minus -- a big one -- is very poor bearing discrimination. I'm hankering for one of the new open array radars . ..
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Old 22-05-2018, 17:58   #14
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Re: Collision Avoidance

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Originally Posted by glmeadows View Post
I am considering to use an AIS transponder (Vesper XB8000) and passive radar reflectors in my small cruising sail boat.
Back in the days before AIS, we used to use radar reflectors. The returns from them vary considerably, and they are not created equal. If your small cruising sail boat is really small, one of the Lunenborg (sp?) lens kind seem to give the best return.

Radar AND AIS would be the ultimate solution but with the radar reflectors and an AIS transponder, my thinking goes like this.

If I have AIS, anyone who has AIS will be able to see me and I will see them. With the reflectors anyone with radar should be able to see me and take defensive action. If they ONLY have radar, I won't be able to see them and will need to depend on their defensive measures. Given all this, if they don't have either radar or AIS, they shouldn't be out at night or in the fog.

Maybe they shouldn't be out there, but there are a multitude of other vessels on the water that have neither AIS nor radar, and in the fog at night, they are relying on luck, hearing, and vision to keep clear of hazards. If your eyes are glued to your AIS, you're gonna miss them, as you would if you were adjusting your radar settings, if you had one.

For the moment, this covers a lot of bases using both AIS and radar reflectors and it also fits my budget. Question...

Would anyone insist upon having both (I.e. Radar and AIS) ? If so, why since being on the water in adverse weather or at night is always a risk even given all the equipment and operational watch and awareness. Again, the only thing I won't see are targets who ONLY have radar. Also, if they've got radar they most likely have AIS.

If what you're asking is why would one have both, it is that they do different jobs. Normally, one ought not to go into unknown anchorages at night, but occasionally, one might. The radar shows you returns from vessels and land, so you get an indication of some of what is there to avoid. Neither timber nor fiberglass give good returns. One of radar's uses for us is to locate the vessel's distance offshore from the break, where the waves are; another is forewarning of squalls. Both are non AIS functions.

It is not true that the only thing you won't see are targets who have only radar. Most fishing boats don't have AIS. Many of them are timber. Many of them are quite small runabouts. Fog happens in daytime, and the small hobby fisherman is not always a keen follower of weather forecasting. When you take your small cruising boat out, if you're the kind of fellow who does his homework, you will have heard the warning of expectation of sea fog in the afternoon, or something like that. Some of the other guys didn't hear it, and perhaps didn't even try to. It is the "real world" of coastal sailing, as opposed to the ideal, where your vessel is the only one it's size out there on the ocean.
It is one of the facts of life that we share the seas with many other boats, who usually are smaller than us, as well as the larger ones that could do us more damage. The little guys hide in the ocean swells, and are sometimes only visible when they're on the top of a swell. Their lights are small and dim, if they have them on. This is especially true in the dawn and dusk hours, when some of them think the fishing is best. The low contrast lighting, plus the swell. You might see aluminum runabouts on the radar, but our radar doesn't "see" the fiberglass ones very well at all.

Ann
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Old 28-05-2018, 08:56   #15
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Re: Collision Avoidance

When I take over the world every boat will be covered in a foot of rubber. Then we will all just bounce off of each other. Rendering radar and AIS obsolete.
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