The Furuno is a fairly inexpensive RADAR and yet according to you, it is
doing
nearly impossible things.

Joe,
You are correct, it does, but it's good if it can. 80 nano sec. is quick.
Many of the commercial sets cannot.
Steve

"Commodore Joe Redcloud" wrote in message
...
On Thu, 5 Jan 2006 06:41:49 +0100, "Steve Lusardi"

wrote:

Larry,
You brought up a good point, but your reasoning is incorrect. All marine
scanners have a 30 degree verticle radiation pattern, This is too
compensate
for roll and heel.

Furuno 1623: Vertical beamwidth 25 degrees (12.5 degrees above and 12.5
degrees
below horizontal)

Furuno 1623: Pulse length .08 ms (short), .3 ms (medium), .8 ms (long)

They operate by dumping high voltage on
the cathode, which rings the hell out of the cavity. They turn off when
the
cavity decides it no longer is excited and the receiver can not turn on
until there is no more energy being emitted from the magnetron. This is
becoming a very big issue in Europe at the moment. There now is a new
commercial regulation as of Jan. '06 specifically pointed at canal traffic
that stipulates that all new RADAR sets work at 50 meters. For exactly the
reason you mentioned in your post. Now that's tough to do.
Steve


Furuno 1623: Minimum range 22m




Commodore Joe Redcloud

On Thu, 05 Jan 2006 12:09:53 GMT, Commodore Joe Redcloud
wrote:

Wayne,
50 feet? I don't think so. Check the transmitter specs and do the math.
Lamda = 3.18 u sec per mile, one way.
Steve



Wayne said "about 50 feet". The actual spec is 22 meters. Not that far off for a
casual remark.

======================================

22 meters sounds about right, about 1 1/2 boat lengths perhaps
although it seems closer then that. I believe Furuno shortens up the
pulse length on the close in ranges to improve resolution.

On Thu, 05 Jan 2006 12:05:25 GMT, Commodore Joe Redcloud
wrote:

The Furuno is a fairly inexpensive RADAR and yet according to you, it is doing
nearly impossible things.

=========================================

I'd be happy to demonstrate my Furuno to anyone who wants to see for
themselves. It has significantly better close in range than either
of my older Raytheon units.

On Thu, 05 Jan 2006 23:23:21 GMT, Commodore Joe Redcloud
wrote:

I bought Furuno based on the observation that virtually all commercial craft use
them. Lobster boats, Ferrys, USCG...

==================================

Absolutely right, and those guys use their gear a lot, and are not shy
about discussing its good and bad points.

I'm happy with mine, and everybody who comes aboard and sees the ARPA
functions in action, raves about it.

Even Mrs B, who is not known to get excited over marine electronics,
thinks it's pretty cool (not sure if she knows what it cost). It is
interesting to go up on deck in the middle of the night when it's my
turn on watch and listen to her calmly explain all the boats she
spotted and avoided in the dark.

How much is that worth?

"Steve Lusardi" wrote in
:

The
restriction at close range is Pulse width and receiver turn on time. A
RADAR mile is 6.36 micro seconds. If you want to see a target 100
yards in front, the RADAR set must transmit a pulse and turn on the
receiver to catch the echo in less than .31 micro seconds. That's a
very tall order with a magnetron, as they are not gated. They operate
by dumping high voltage on the cathode, which rings the hell out of
the cavity. They turn off when the cavity decides it no longer is
excited and the receiver can not turn on until there is no more energy
being emitted from the magnetron. This is becoming a very big issue in
Europe at the moment. There now is a new commercial regulation as of
Jan. '06 specifically pointed at canal traffic that stipulates that
all new RADAR sets work at 50 meters. For exactly the reason you
mentioned in your post. Now that's tough to do. Steve


Before the water in the dome rots the hell out of the Raymarine radar on
Lionheart, that little sucker can see the 4th boat down our dock on the
1/8 mile range! It even plots the dock correctly from our 20' antenna
on the mizzen. Pulse width must be picoseconds. I don't think it ever
gets very wide to keep resolution high and current drain low. Hell, the
scanner cable to the RL70CRC display where it gets its power from has
very small, long power conductors and most of the power has got to be
heating up the maggie filaments. I had a helluva time explaining to
some captains why a 2KW radar didn't draw more than 2KW off their
batteries. Some of them were afraid to turn 'em on without the engine
charging all that power!...(c;

AIS to the rescue! Need shore fixed stations with all up-to-date
obstruction data coming out of them....

Commodore Joe Redcloud wrote in
:

Furuno 1623: Vertical beamwidth 25 degrees (12.5 degrees above and
12.5 degrees below horizontal)



So, if you're heeled over 25 degrees in the big blow, sideways radar
coverage sucks.....I've seen that....

Commodore Joe Redcloud wrote in
:

If you are heeled over 25 degrees in a blow, you might consider
shortening sail. You will probably go just as fast or faster, and your
rudder will be more effective.


Commodore Joe Redcloud



You mean the handrail isn't SUPPOSED to be dragging in the water?...(c;

I thought that spray from it wasn't supposed to get me wet at the helm.

On Fri, 06 Jan 2006 00:34:49 -0500, Larry wrote:

AIS to the rescue! Need shore fixed stations with all up-to-date
obstruction data coming out of them....

And that will tell you about the 16 ft Boston Whaler fishing in the
fog bank right in front of you?

In article ,
Wayne.B wrote:

On Thu, 05 Jan 2006 12:05:25 GMT, Commodore Joe Redcloud
wrote:

The Furuno is a fairly inexpensive RADAR and yet according to you, it is
doing
nearly impossible things.

=========================================

I'd be happy to demonstrate my Furuno to anyone who wants to see for
themselves. It has significantly better close in range than either
of my older Raytheon units.


Ok, I feel a Furuno Story coming on....... Many years ago (1975) I
installed one of the first Furuno KR-124 Radars imported into the
US, on a 85' Yatch in Lake Union, Seattle, Washington. This vessel
had a Professional Skipper & Crew. (ex coastie) Takes about 3 hours
if the antenna, and display are already mounted, and the interconnect
cable is already run but not terminated. Skipper was a sharpeyed older
gent, who wasn't sure that this kid,( myself) knew anything about
"Anything", and was determined to keep an eye on the whole process.
Got everything connected and fired up the radar, to do the Sea Trial,
and get the Heading Flash Reed Switch set to ships head. Nice clear
amazing picture on that analog display. As we were pulling away from the
dock, the skipper looks at the display and asks, "What is all that
clutter, down here in the port quadrant at .25 miles?". I look, and see
a bunch of targets, close together, and then look out with a set of
Binocs, and see a small group of Seagulls sitting on the water. "It is
that group of Gull's over there" says I. He says, "Bull ****". "No",
says I, "Wait till that seaplane taxi's over there, and they all take
flight, and the targets will all disappear of the scope". Sure enough
the Seaplane taxi's right thru the group, and all the targets disappear
from the scope except one. "Look, see they all disapperaed, just like I
said" skipper looks in the scope and says, "Nope, kid there is still one
target there". "Well", says I, "There MUST be something in the water,
over there". Skipper says "Bull ****, I can't see anything there with
these glasses, but we'll just cruise on over and look." So we idle on
over, and sure enough, here is a styrofoam cup floating in the water.
We pick it up, ad set course for the Can, right off GasWorks Park to
use as a Heading Flash setup target, and sure enough when we get .25
Miles from where the cup was, the skipper checks the scope and no more
target. "Hell, that is one great Radar to be able to pick up a strofoam
cup at a quarter mile. Never had that kind of luck with any of my
Raytheon Radars". I just smiled.........

Of course you have to remember that the KR-124 was a true 9Kw radar,
with a real good slotline 3Ft antenna, an excellent Logrythmic
IF Strip, and brand new 1N415E Crystals. When compared to what was
out in the fleet at the time, (Raytheon 1500's,1700's 1900's and Decca
101's and 202's) this was an order of magnitude leap in commercial
radar technology. And it didn't require ANY service for years at a
time, which really made the semi-monthly Raytheon Service look BAD.
That radar and it's follow on KR-248, and KR-448 is what MADE the Furuno
Name in the High Seas Fishing Fleets and North Pacific Coastal Freight
Fleets.

Bruce in alaska
--
add a 2 before @

In article ,
Wayne.B wrote:

On Thu, 05 Jan 2006 23:23:21 GMT, Commodore Joe Redcloud
wrote:

I bought Furuno based on the observation that virtually all commercial craft
use
them. Lobster boats, Ferrys, USCG...

==================================

Absolutely right, and those guys use their gear a lot, and are not shy
about discussing its good and bad points.

I'm happy with mine, and everybody who comes aboard and sees the ARPA
functions in action, raves about it.

Even Mrs B, who is not known to get excited over marine electronics,
thinks it's pretty cool (not sure if she knows what it cost). It is
interesting to go up on deck in the middle of the night when it's my
turn on watch and listen to her calmly explain all the boats she
spotted and avoided in the dark.

How much is that worth?


Priceless, in anyones estimation...........

Me