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Author Topic:   RADAR
WSTEFFENS posted 03-09-2002 10:34 AM ET (US)   Profile for WSTEFFENS   Send Email to WSTEFFENS  
For the past several seasons I have considered installing a LCD radar unit. However after reading mfg's lit and catalogue advisors and several articles in magazines I have some questions.

Most advisors & mfg's say you need 4kw to "punch thru" fog & rain. Since most small radar units are in the 1.5 to 2.5 kw transmit power with a range of 16nm, will the small unit be able to see 3 nm in such conditions, since 3nm is pratical line of sight when the dome is mounted 8' above the water line?

What is the experience of you fellows in the foggy NE & NW?

Best
WLS

flieman posted 03-09-2002 11:59 AM ET (US)     Profile for flieman  Send Email to flieman     
The 2 kw units do not have a lot of punch or clarity, that is the main thing. They will get thru fog or rain and pick up a set of jettys but when it comes to picking up a small seabuoy or small boat that can be a problem. The max range on these unit usually cannot be used on small boats anyways because of height restrictions. I had a 2 kw unit on my Hatteras and it was worthless in my eyes, I then put a 4 kw unit and what a difference. I never had trust in the 2 kw unit, maybe I just did not know how to adjust it like I did the old CRT 4kw. The radome on the 4 kw is big and alot of small boats cannot handle them so you may have to settle for a 2 kw.
My thoughts
FLieman
WSTEFFENS posted 03-10-2002 04:19 PM ET (US)     Profile for WSTEFFENS  Send Email to WSTEFFENS     
Flieman:
Thanks for the reply. I trust the mounting point of the antenna was higher than 8' above the surface. With a vessel the size of a Hatt, I would expect that your target recognition requirements would be more important as your reaction response time is greater than a 25' vessel.

In your experience, does the target aquisition/recognition performance improve with the reduction in range. I.e. does sharpness of immage recogniton improve when opperating on a .25 mile range vs a 1 mile range?
Thanks

Best
WLS

flieman posted 03-10-2002 08:05 PM ET (US)     Profile for flieman  Send Email to flieman     
It definitly will improve with range being lower but the definition will not be as good with a 2 kw range as with a 4 kw. The one thing that I never trusted was as the seas got rough then the boat was obviously rocking and rolling and that is were I had problems with images coming and going on the screen. That is when I lost trust in the unit. Mine was a Sitex and I had big big words with them, you should see the emails I recieved from them. I was not the kindest in the world myself but the guy told me that if I could not adjust the radar then maybe I should not run a boat. You can imagine the reply I made, I then took the radar and tied the radome to the anchor rope and hung it from the bow pulpit and took a picture. I sent the picture to him and said "Look this radar does not make a good anchor". You can imagine the reply I got from him saying Sitex could sue me for talking bad about them. I promptly took everything that said Sitex on any of my boats off and sent it to them. I probably had a bad experience with them as I would never own anything that says Sitex on it again. I do know how to adjust a radar but maybe that Sitex unit was not a powerful enough unit, I do know that I have complete confidence in my 4 kw Furuno now. Radar is neat to have and you should use it in good or bad weather so you really know how to use it so you can trust what you are doing when a storm comes up and it is blowing 30 knots and raining.
triblet posted 03-10-2002 09:48 PM ET (US)     Profile for triblet  Send Email to triblet     
It seems to me (I'm a EE, but have never
owned a radar) that there are (at least)
three independent factors in a radar:

- The display.

- The RF electronics (transmitter and
reciever), including, but not limited to,
KWs.

- The antenna.

It's important to understand the function,
capabilities, and variables of each. I
regularly see people labasting "LCD RADARS"
for problems that are pretty clearly low
power or low res antenna (which go with the
(relatively) low price of LCD radars), not
the LCD display. Don't blame the LCD, blame
the low price which means low KW
and a little antenna that throws a big wide beam.

If the boat is rocking, and you have a narrow
beam, some of the time you are going to be
looking for submarines or airplanes (see
story below). If you have a wide beam, you
loose range (same as VHF) and detail but part
of the beam is still pointed at the horizon.

The story: Several years ago I was aboard the
Cypress Sea (Monterey commercial dive boat).
We were headed back north from Carmel Bay
along the 17 Mile Drive, drooling at Clint
Eastwood's house, when a HUGE blip pops onto
the radar. Vis was two or three miles,
low clouds. Range to the target: about
three miles. And there's NEVER anything BIG
close inshore hereabouts. The commercial
traffic is all 10 miles out because that's
the straight line from San Francisco to LA.
Capt. Phil starts getting a bit concerned.
No, a LOT concerned, and that's not like him.
Range to target gets down to 1.5 miles, and
Phil has everybody in the wheelhouse looking.
We should be able to see this big puppy now.
Then the ceiling lifts a bit: Goodyear Blimp,
heading home after last night's game at
Candlestick. ;-)

Final item: small fibreglass boats don't show
up worth a damn on radar. I've spent a fair
amount of time in Capt. Phil's wheelhouse,
and often they just don't show at all.


Chuck

flieman posted 03-10-2002 10:10 PM ET (US)     Profile for flieman  Send Email to flieman     
That is very true, but after you know your radar and can tune it properly you can pick up little boats, metal can buoys and know what the blips are. A giant blip like the Goodyear blimp would scare the heck out of anybody because you have never seen anything like that before. You can pick up small boats in rough seas and they will come and go but if you trust your judgement you will know what you have. The LCD screen has nothing to do with it but the 2 KW (which is common on LCD radars) is so inconsistent that you are not sure. Only my 2 C worth.
Flieman
WSTEFFENS posted 03-11-2002 04:22 PM ET (US)     Profile for WSTEFFENS  Send Email to WSTEFFENS     
Fli& Trib:
Thanks for the response. I am shocked about the experience with the Sitex (Koden)unit as it was highly thought of in several reviews I have read. This in light of the lauding of antenna design eliminating side lobe echo interferance.

I am getting the feeling that the poor performance is the reason why low power (off brand) units seem to be being dropped from production and availability as they are useless in the conditions when you really need the capability.

Any further information would be greatly appreciated!

Best

WLS

newboater posted 03-12-2002 11:21 AM ET (US)     Profile for newboater  Send Email to newboater     
WLS,

I had a JRC 1000 on our 45-foot sailboat for a couple of years. This is the cheapest unit you can buy, power is 1.5kw, and is called a 16 mi radar. I always could see land visually before I could on radar. The furthest out I could see land on radar, Iím talking big tall mountains, was about 12 mi. I could see freighters 6-8 miles out. I couldnít reliably see 25-foot boats unless they were within a mile. I probably would never see a classic Whaler on radar.

I wasnít happy with the performance I was getting so I threw more money at it and upgraded to a Furuno 1712. Itís a 2.2 kw, 24-mile model, and hopefully it will be able to ďseeĒ more. I canít comment on its performance because itís still in a box on the floor.

We bought the radar because of a couple near misses at night with unlit small boats. We thought we would be able to prevent reoccurrences if we had radar, but now Iím not so sure. It is good to be able to quickly tell how far you are from shore, a buoy, or a big boat. If the visibility was so bad, you canít see the jetty, well Iíd still wait it out offshore before Iíd trust my life and boat to radar.

Dave S.
San Diego

Whalerdan posted 03-12-2002 12:39 PM ET (US)     Profile for Whalerdan  Send Email to Whalerdan     
I don't know about boat radar, but I know on our aircraft, radar is not something you want to stand in front of. Even if they told me it was safe, I would be worried about having radar transmitting above my head.
WSTEFFENS posted 03-12-2002 01:25 PM ET (US)     Profile for WSTEFFENS  Send Email to WSTEFFENS     
Dave & Dan:

Again thanks for the reply. This is the sort of information I was in search of.

I too was interested in seeing in the dark and bad weather, small boats & objects that shouldn't be there. (not on the charts)

I agree that you wouldn't want to be irradiated by the transmitter. Why do you thnk Ammana & Litton called their original micowave ovens "Radar range". Dome tower mounting would have to be very carefully thought out.

Dave I would be very intested in how your new unit performs, as it seems to me to be a likely candidate for me. I realistically figure that if I can see 1 km reliably in trashy weather I would be in good shape. I would know where land masses are , as one guy put it "Long Island hasn't moved in thousands of years"' but the ability to see markers and un-lit boats is important, as well as large tankers and ore boats.

Again thanks for your thoughts. I am not interested in trashing a product just understanding what its real capabilities are and if it is of value.

Best

WLS

triblet posted 03-12-2002 02:23 PM ET (US)     Profile for triblet  Send Email to triblet     
I'm sure the radar makers have specs on where
to mount the unit relative to people.

Chuck

lhg posted 03-12-2002 03:34 PM ET (US)     Profile for lhg    
As an aside, just to show how wide ranging this website is, on page 11 of Cetacea, you can see a picture of a woman whose father invented Radar! He was one of 5 British scientist/engineers who designed and produced the first functional radar in the world for the British military during World War II. After the war, he was brought to the US for development of our systems.

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