Radar - 18" vs 24"

J

jlastofka

New member
I found a LOT of old threads here on radar and read them all and learned some stuff. I'm about to buy a radar unit to go with my Garmin 4212 plotter screen. They make four versions now from about $1000 to about twice that. There's an 18" standard and a high-definition version, both having a 5 degree beam width. And then a pair of similar 24" versions, both with 3.6 degree beam.
I've never used a radar before. I expect the narrower beam would give a sharper image and the newer electronics probably help, too. I can spend the money for the bigger, newer version, but I'm wondering if the smaller standard version would be more than adequate for half the price.
We get periods of fog here near San Diego, and we traverse shipping lanes. (And it gets dark at night......)
Will I just be watching for ships, or will I be seeing lots of other useful information that will make a better resolution unit worth the bucks?
Thanks for any informed opinions. I expect I might want the MARPA add-on, too.

Jeff
 
I don't know if I have an informed opinion or not but I've been using radar on my boats for about 15 years. What the the 3.6 is going to give you over the 5 is better target separation at a farther distance. For example your approaching a pair of channel markers. The 5 will show them as one target where as the 3.6 will show them as two different targets. As you get closer to them the 5 will also show them as two targets. IMHO for the boating most of us do the difference in performance does not out way the cost. There are other people that will give you a much better description than me but this will get you started.

Roger
 
Roger gives a very good assesment of the beam width and descrimination between nearby targets.

For San Diego the 18" will be OK. I sailed S. Calif. for over 30 years with no radar. I would have liked to have had it a dozen or so times. Once in my C Dory I did find the Radar essential--and a small dome was fine.

If you can afford the 24" it will give a better picture, but not essential.

I have never owned more than a 2KW--including 24 mile units on passagemaking boats--since most of the time is at 3 to 6 mile range, in most weather it does not make much difference. But if it was only $500 more to get 4 KW and a 24" scanner, I would go for it. There is a good arguement that there will be slightly better penetration in rain. I have personally found that 2 Kw was fine in fog. You also have to learn to tune the set--Auto Tune is often NOT the best setting. It takes time to learn how to use it. Keep it on during the day to learn.
 
The best general rule of thumb is that the 24 inch will see the same target at a greater distance than an 18 inch. With the little experience I have had with radar, when I need it, I am running slow with the range set to 1/2 mile or less. I can generally detect most boats within 1/4 mile with kayaks being an exception. I don't know if a 24 inch would materially change that, since the main reason I am running slow is to try to miss things radars don't detect very well if at all, logs and other debris in the water.

On the other hand, if my GPS failed and I was using the radar to navigate, high resolution with greater range would be everything. Trying to match a radar return with the shore, islands and mountains is not really easy with my Furuno 1623. With an 1/8 mile setting I think I could a least find the fuel dock at the Whittier small boat harbor at a slow enough speed to not cause much damage in 0/0 visibility.

No matter what you select, I would try some "instrument" boating on a sunny day with the "hood on" while someone else watches for obstacles. I have done it a couple of times and what really surprised me was how difficult it was to maintain a straight course at slow speed with no visual references. The GPS simply does not respond fast enough. A compass then becomes a really useful tool.

The last thing I learned about instrument boating at night was the dimmer on the radar's back light didn't work on my Furuno and on the lowest light setting the GPS the backlights on the keys went off. The thing about using electronics at night is it doesn't do night vision much good. I finally stopped turned everything off, let my eyes adjust, and realized I could really see a lot even though it was cloudy and raining. So I am now going to look for some red plastic covers for my GPS, radar, and radio to tone down the light and not destroy night vision.

I guess the lesson I learned is the radar is only part of a system of things that helps you navigate in poor visibility. Whether its 18 or 24 inches may be a personal preference, but consider as part of everything else that helps you navigate.
 
We nearly always have two people on watch when running in darkness. Marie rarelly looks at the instruments, and if she does, it is with one eye closed--thus she retains her night vision.

The item which is important is the amount of light--not necessarilly the color of the light. Red is a hold over from photographic film, where dark room lights were red, since there was less sensivity to the red spectrum in most films.

The arguements for various colors are lengthy and involve retinal physiology. But dim of any color is better. Light gels are also a good material for reduction of light intensity.

We have done a lot of navigation with radar, because we used it for 20 years before chart plotters became affordiable. It is different than chart plotters, and takes practice.
 
I'm no radar expert but on thing I've heard is that going bigger or more wattage won't necessarily let you see farther unless you can get the radome up higher. On our boats it may not make any difference.
 
tpbrady":2uuq2jiw said:
No matter what you select, I would try some "instrument" boating on a sunny day with the "hood on" while someone else watches for obstacles. I have done it a couple of times and what really surprised me was how difficult it was to maintain a straight course at slow speed with no visual references. The GPS simply does not respond fast enough. A compass then becomes a really useful tool.

T.
Click to expand...

I always run with my radar on, day, night, sunny or not. A sunny day is just another training day. Learn what the radar display looks like while you have the benefit of good visibility. Then at night or fogged in you are comfortable with what the radar display is showing you. (You know what that 400 foot barge and tug as well as that little unlit buoy look like on the display)

....difficult it was to maintain a straight course at slow speed with no visual references. ....

This is where I find the autopilot to be at its best. It is unbelievable how, at the blink of an eye, you can get off course in poor/no vis weather. One time before I got autopilot and gps, I was fogged in and making my way into Pensacola pass. My course was due north. I passed no. 8 buoy and then "glanced" at my chart to confirm my location. When I looked up again an scanned the compass it said I was going due south. My brain just would not compute that I had made a 180 turn until I saw the same no. 8 buoy again. Learn your instruments. Believe your instruments...


Roger
 
Judy and I also boat around San Diego, and as a matter of fact we're going fishing out of Oceanside Tuesday. We bought a radar for our sailboat, at Judy's instance, and now I take credit for it. Journey On has a 2 kw JRC radar. Let me encourage you to install a radar by all means. I agree with thataway as to the radar requirements for a small boat in such salubrious weather as San Diego has.

However, you also get my opinion. My conclusion is that for a small boat such as a C-Dory a good minimal radar is equal to the best.

First the radar dome is mounted low (<10 ft.) on a C-Dory, and the horizon at that height is 3.6 nmi. The 16 mi radar will go past the horizon.

Second, the higher power of a 4 kw over a 2 KW does offer better signal definition, as does the 24" antenna, but neither is required for small boat navigation, certainly around So Cal.

Third, note that the new high-definition versions don't increase either the antenna size or radiated power. What they do is provide better signal processing in the radar dome. (ALL new X-band radars do all the signal processing in the dome and just send down a digital signal.) The amount of "better" is not quantified in their brochures; however the new plain radar on Journey On does a good job. As Bob says, learn how to tune it, and Toms point is important: learn how to read it before you need it..

If you've got this far, please get a radar. The price is up to you, but I'd get the cheap one.

the southern Boris
 
I made a couple cardboard mockups and the difference between the 18" and 24" models is HUGE. A little math shows the volume is almost exactly double, considering the diameters and heights. That explains the way the models look.

I checked with a couple friends at the local yacht club and they also agree with what people are telling me here. Sounds like I'll be saving some money and buying the 18" model. I think I'll wait a few weeks and spend the extra $170 for the new High Definition model. No telling if it's worth it, but it's the new model, so....

I believe I'll spend the 'savings' on a Fujinon 14x40 stabilized binocular, which has also received exceptional reviews here at C-Brats R Us.

Thanks for the help,

Jeff
 
You will enjoy the stabalized binoculars. I use those more than I use Radar. But around here, often navigation is "by the numbers"...on the pilings which mark the ICW.
 
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