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Old 12-11-2011, 08:11   #211
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Re: Radar or Not ?

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Originally Posted by conachair View Post
I meant I couldn't fit both, so I'll stick with the raymarine 2kW
but but... that is a conventional set, not the new broadband or did I miss something?

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Originally Posted by conachair View Post
You seem very sure that other vessels are watching. I know from experience that the big boys see me on radar, small stuff I don't trust anyway.

Do the big boys constantly watch for class b ais targets?

I really don't know what goes on on a bridge.

But for now will happily carry on looking after myself with a reciever, and not assume that I've been seen.
No, you don't have to do that... you can be 100% sure that they don't see you on AIS because you have a receiver only.

If you have a plastic or wooden boat without active radar reflector/transponder you can also bet that the ships ARPA system is NOT tracking you and thus will not sound warnings for close proximity. The more one pushes these tools away (radar reflector, AIS transponder), the less visible one becomes for ships, making it harder to cope with safe navigation in busy areas, because the other traffic mostly aren't considering you. Like others wrote, we too see ships adjusting to our presence on their AIS systems like making course corrections or more often, speed corrections. We never saw that happen before...

But no matter what tools you use, NEVER assume that they will see and spare you. Colregs etc. are clear on that.

Ships don't constantly watch AIS targets... it is the internal software that does that and generate audible and visual warnings to attract the attention of personnel on the bridge. If they get alarms from class-B targets faster than they can switch off, they can enable filters that include stationary vessels and yes, also class-B signals. But they do this to increase safety and with so much happening, you can bet they have eyes on AIS, radar and the safety circle around their ship.

cheers,
Nick.
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Old 12-11-2011, 08:27   #212
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Re: Radar or Not ?

Our AIS shows targets well beyond distances what our radar will and provide important and useful information about any selected target. We have, and use, both AIS and RADAR and wouldn't want to attempt any night passages without either in our current cruising area (Panama). Try entering the Panama anchorages with over 70 AIS targets on the screen, blowing 20+ knot winds, and rain so heavy you can't see 200'.
We also use our Garmin Radar to check the accuracy of our Chartplotter (overlay mode makes it easy) and have "found" a few islands 1/4 -1/2 mile off their chart position.
I must admit, using the Chartplotter, Sonar, Radar, and AIS provide more restful passages for the Captain and crew. But, the prudent sailor doesn't rely on just one or two pieces of equipment....have a good set of binoculars within reach and keep a sharp eye out at ALL times!
No single piece of equipment is useful if you don't know how to USE it correctly. In the darkness of night you may only see one little nav light in the distance, it's only during the light of day you see what that "little" nav light is REALLY connected to!
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Old 12-11-2011, 08:41   #213
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Re: Radar or Not ?

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That unit is class B.

Hope for the best, plan for the worst and don't assume anything

USCG Issues Safety Alert On Class B AIS
Obviously, I'm speaking architecturally. Implementation is another matter.

Hence, one reason my boat is AIS-less! It's gets tiring paying high $$ to be an early adopter and beta testing for the industry and manufacturer.

But the issue you bring to light is one to blame on the marine industry. It's obvious that class B was an after thought and not considered in the early architectural phase. This phenomena seems more the norm in the marine industry. NMEA2000 is another fine example! I work in a high tech industry, if we moved at the same pace, twisted pair Ethernet would just now becoming common place.
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Old 12-11-2011, 08:54   #214
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Re: Radar or Not ?

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Originally Posted by conachair View Post
You seem very sure that other vessels are watching. I know from experience that the big boys see me on radar, small stuff I don't trust anyway.

Do the big boys constantly watch for class b ais targets?

I really don't know what goes on on a bridge.

But for now will happily carry on looking after myself with a reciever, and not assume that I've been seen.
I know 100% that the big boys don't see your AIS receiver.

Collision avoidance is a multiplayer - team effort. Yep, you can never be 100% assured that the other player will do their job, but you can be assured they won't if you don't invite them to the game.
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Old 12-11-2011, 09:17   #215
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Re: Radar or Not ?

Saying that the big boats are not watching is nonsense.

Who says this? People who never been on the bridge?

It must be true there are some lame officers out there - you know pilots (plane pilots!) fall asleep on long flights too.

But these are single cases of when things go wrong. And to say that the big guys are not watching is offensive.

Big guys ARE watching. Meanwhile vast majority of cruisers spend time down below while they should be in the cockpit, watching.

b.
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Old 12-11-2011, 09:39   #216
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Re: Radar or Not ?

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Saying that the big boats are not watching is nonsense.
Barnie, I think you're talking about watching in general while I was talking about eyes glued to screen by dedicated radar operator (or AIS). I think that this only happens on navy ships.

I agree with you that ships do watch; up until now we only met one ship that didn't (Florida Straits, 2003). This excludes commercial fishing boats of course, who never have a look out while fishing.

ciao!
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Old 12-11-2011, 09:47   #217
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Re: Radar or Not ?

-- Class-B AIS --

Some people are misinterpreting that old USCG Class-B Safety Alert. Class-B does show up on the Minimum Keyboard Display and chartplotter displays, it's just that on the older displays the Class-B vessel name and other "static" data may not be displayed. Position, Course, and Speed of the Class-B target are displayed, regardless of the age of the AIS equipment on a vessel's bridge.

The more important issue is whether the ship's crew are paying attention. I've asked ships on the high seas if they could see me on radar, and (if they even answered my VHF hail), occasionally the answer was "wait a minute while I turn on the radar -- yes, I see you now."

Now that I have a Class-B transponder, all the ships I have asked have seen my AIS signal. For the purposes of collision-avoidance, unless proven otherwise I still assume that the other guys are all asleep.

[edit: I'm talking about ships on the high seas, not those in high-traffic areas.]
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Old 12-11-2011, 09:56   #218
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Re: Radar or Not ?

I think a good point for AIS hasn't been discussed yet... in contrast to radar, AIS can "see" behind land features like a cape, mountain etc. This means that AIS can warn for collision while even the best ARPA stays silent.

I think there was a collision in Asia where AIS warning was ignored and ARPA stayed quiet? anybody know the details?

ciao!
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Old 12-11-2011, 10:03   #219
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Re: Radar or Not ?

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For the purposes of collision-avoidance, unless proven otherwise I still assume that the other guys are all asleep.
Very wise. It is like defensive driving in an auto: always assume the other guy is not paying attention and always be prepared in case your assumption is correct.
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Old 12-11-2011, 11:07   #220
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Re: Radar or Not ?

Regarding AIS. Here is one observation I can offer:

When we are not out sailing the Great Lakes, we actually live right on the shores of Thunder Bay. We have a perfect view of all the lakers, salties and work boats that use this rather busy fresh water port. Even though ALL of them should be transmitting AIS signals, it is not uncommon to see a ship with no attached signal. For whatever reason, there is a small but not-insignificant percentage of big vessels running silent on AIS.

If it came down to a choice, I would go with radar over AIS. Just like I would choose a depth sounder over a chart plotter.
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Old 12-11-2011, 11:16   #221
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Re: Radar or Not ?

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Hence, one reason my boat is AIS-less!
That just confuses me. As said before, why not have a piece of kit onboard which costs less than a shiney jacket and provides a lot of very accurate useful info?

What's not to like??
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Old 12-11-2011, 11:26   #222
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Re: Radar or Not ?

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Originally Posted by s/v Jedi View Post
but but... that is a conventional set, not the new broadband or did I miss something?.
It was a response to a previous comment that a boat with broadband should also have conventional radar. 2 radars onboard is a situation I will never be in.

Now if there was cheap PC software that i could plug a 4g into.....



Quote:
But no matter what tools you use, NEVER assume that they will see and spare you. Colregs etc. are clear on that.

Ships don't constantly watch AIS targets... it is the internal software that does that and generate audible and visual warnings to attract the attention of personnel on the bridge. If they get alarms from class-B targets faster than they can switch off, they can enable filters that include stationary vessels and yes, also class-B signals. But they do this to increase safety and with so much happening, you can bet they have eyes on AIS, radar and the safety circle around their ship.
Thanks,

I know from experience that any ship I call up offshore say they've been watching me on radar, so that side of things seems to work OK. On other forums there have been discussions of the ais being seperate and not so much attention paid to the disply, but have no idea if enough to satisfy the legal setup or how it works in the real world.

Inshore I try to keep out of the way of the big boys so they shouldn't need to be bothered by me. Ais makes this easy. Doing it with radar is a pita when you eyes would be better off on deck.
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Old 12-11-2011, 11:52   #223
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Re: Radar or Not ?

For the last time every boat on the water is not transmitting AIS, every boat on the water is not receiving AIS.

Every boat on the water is a potential torpedo, and if headed in your direction, can sink your vessel.

Happy bliss runs without radar.

You are the master of your vessel.

You are responsible.

To assume that AIS is going to save you is happy bliss.

A vessel with an operating radar, will avoid more of those torpedoes then a vessel operating with only AIS.

Lloyd
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Old 12-11-2011, 12:02   #224
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Re: Radar or Not ?

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For the last time every boat on the water is not transmitting AIS, every boat on the water is not receiving AIS.
I don't think anyone said that they were


Almost all of the big ones do and for a few hundred dollars you can get a little box which will tell you exactly where they are and what they are up to.

Why do you think that is such a bad thing???
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Old 12-11-2011, 12:37   #225
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Re: Radar or Not ?

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Originally Posted by conachair View Post
I don't think anyone said that they were


Almost all of the big ones do and for a few hundred dollars you can get a little box which will tell you exactly where they are and what they are up to.

Why do you think that is such a bad thing???
First I didn't say AIS is a bad thing.

Second the OP was should I buy a radar, bc I have an AIS already?

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Originally Posted by stevensuf View Post
I'm slowly fitting out my new to me boat, I am trying to keep the budget as low as i can reasonably get away with. I have installed a vhf with ais and linked it to the plotter, I am wondering if it is worth the extra 1000 pounds to add radar?
2 years ago IIRC here in Seattle on a Summers night after dark, we had a fatality accident, when a fast moving runabout ran up the stern of a sailboat.

Neither had AIS nor Radar. If the sailboat would of had radar, and it was on and working as they clearly should of had.

The fatality could of been avoided by the master of the sailboat. If the Sailboat would of had just an AIS the fatality still would not of been avoided.

Can you imagine the pain the Master of this Vessel continues to bear, at the loss of his own loved one caused by, and incident he could have well avoided.

Lloyd
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