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Old 03-11-2011, 13:16   #1
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How Reliable Are Radar Alarms ?

There are a few realities I must confront:

1. While the ideal is to be able to have experienced crew on watch at all times, the reality is sometimes I will have to single hand because of the lack of suitable crew......or I'll never go cruising. If I have to single hand I want to do it with as a high a safety margin as possible.

2. When a vessel is closing on me (large or small) my concern is not whether it might be one of those dangerous single handers. My question is: Have they seen me? I am not necessarily more confident that a fully crewed ship is any more likely to see me than the single hander's radar sweep with guard alarm set.

3. To those who think it's unlikely that we'd be on a collision course mid ocean, get this. I recently sailed from New Caladonia to Brisbane and we saw only one ship (a huge tanker) all the way. It approached on our starboard beam and yes we would have collided if we didn't take avoidance measures. We were sailing and of course it was us who had to alter course as the distance between us began to get uncomfortable. A sobering thought.

So my question is, How good are the latest radar alarms?

Greg
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Old 03-11-2011, 13:35   #2
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Re: How Reliable Are Radar Alarms ?

My problem with alarms generally (e.g radar, anchor drag, AIS alerts, high water sensors) is that they are too soft. Oh, they go off, but you can barely hear them.
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Old 03-11-2011, 14:04   #3
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Re: How Reliable Are Radar Alarms ?

I bought an alarm from RadioShack, and emailed it's specs to Raymarine, asking if there would be any electronic reason not to attach it to to the radar. He responded that it was OK, but he also gave me a stern lecture about how unwise it was to sleep while sailing.

I forget how many decibels the alarm was, but it was very loud!
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Old 03-11-2011, 14:41   #4
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Re: How Reliable Are Radar Alarms ?

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Originally Posted by Eleebana View Post
So my question is, How good are the latest radar alarms?

Greg
I've done a fair bit of offshore solo, using a raymarine 2Kw scanner with a sl72 display. As for the radar, the alarm isn't loud enough, one of these plugs into the seatalk and can be loud as you like. The alarm is a bit of a compromise, you need to turn the gain down enough to stop constant alarms but high enough to see stuff, not so much of a problem with the big boys but another yacht might not set it off it the waves are up a bit. Also very useful for alerting you to squalls. I'd usually have a guard zone between 1 mile and 5 miles.
In tandom with the radar and really very useful I have a cheap nasa ais reciever, quite a loud alarm and you will see straight away even through sleep muddled eyes which way the other vessel's heading relative to yours and if you need to do something. Think I set it at 5 miles. Another thing with both alarms is that you're awake until the ship dissappears off the other side of the alarm circle, if it's a glancing blow then ais helps as you don't need to get fully awake to see what's going on.
More generally, I can never relax util off the continental shelf when all the fishing and coastal traffic dissappears and you're into the peaceful deep ocean, til then sleep is in short bursts.
You'll never get rid of risk at sea, less so solo but with a decent radar and ais you're a fair way down the line.
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Old 03-11-2011, 14:55   #5
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Re: How Reliable Are Radar Alarms ?

A dumb machine can never be as good as a pair of eyes attached to a (fully functioning), human brain, but with both Ais, and Radar, it is safer than nothing. Even with both I would keep sleep periods short.

It is always possible you could encounter something too small to show up on Radar, and doesn't have an AIS. (debris, small yacht, etc...)
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Old 03-11-2011, 15:25   #6
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Re: How Reliable Are Radar Alarms ?

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It is always possible you could encounter something too small to show up on Radar, and doesn't have an AIS. (debris, small yacht, etc...)
With AIS recievers so cheap and low power draw there really isn't much argument not to have both.
Just reread the OP, "latest radar alarms" - did you mean the likes of broadband, Greg? Now that wouild be interesting to hear about. One of these
looks great on the spec, lovely low power but has anyone actually tried using the alarm on something like that?
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Old 03-11-2011, 15:35   #7
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Re: How Reliable Are Radar Alarms ?

You're either going to turn the gain up and get false positives all the time, or turn the gain too low and miss smaller boats. They don't substitute for being on watch, and if you have a watch the alarm is just an annoyance.
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Old 03-11-2011, 16:10   #8
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Re: How Reliable Are Radar Alarms ?

I like that add-on alarm unit. But to me it looks best as a louder anchor alarm. The AIS seems a better answer out in the open when really it's frieghters to be watching for.
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Old 03-11-2011, 16:29   #9
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Re: How Reliable Are Radar Alarms ?

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Originally Posted by Don Lucas View Post
I like that add-on alarm unit. But to me it looks best as a louder anchor alarm. The AIS seems a better answer out in the open when really it's frieghters to be watching for.
Both is best

I've slept with just the ais to save power, but don't really feel entirely comfortable with it. Even if i can't remember ever seeing anything smaller than the big boys offshore and then only maybe one or 2 a week.
Getting woken when there's a squall close by is useful too which only radar can do, not just to stick a reef in maybe but to get the shampoo out and a bucket under the gooseneck
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Old 03-11-2011, 17:16   #10
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Re: How Reliable Are Radar Alarms ?

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Originally Posted by Eleebana View Post
So my question is, How good are the latest radar alarms?

Greg
Hi,

This is my thought earlier today on another thread:

"...Interestingly, I was reading opinions of radar alarms / enhancers owners where some claim the newer types of radars do not activate some of the (generic: CARD, Merveille, SeaMe, etc..) toys. If confirmed, this would be sad news to all those who want to buy some safety on the budget.

It looks like while we are gaining on AIS we might be loosing on radar alarms."

Depending on what you call 'the latest radar alarms'. The alarms as used on radars are said to be very good. The toys as mentioned in my quote are said to be less responsive to the new kinds of radar.

Hard to say without some extensive real world testing.

b.
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