In article ,
Boeland wrote:

Knowing nothing about radars and transponders could you tell us what
brands are there and how they function. Do they need to be attached to
a radar or standalone and do they respond only to Search and Rescue
radar signals?
Thanks

There is no such thing as a "Search and Rescue Radar" in the Maritime
Mobile Radio Service. There are three common Frequency Bands that
Marine Radars operate in.

S Band 2.4 - 3.1 Ghz
X Band 9.3 - 9.5 Ghz
Ku Band 14.0 - 14.05 Ghz

S Band is used on Large Ships for Long Distances and Weather/Storm
Watches.

X Band is the most common, and 95% of Marine Radars, as well as 99%
of non-commercial Marine Radars use this band. Good out to a Max Range
of 100 Miles, or so.

Ku Band Never actually seen a Ku Band Marine Radar in 40 years in
the Marine Electronics Biz, but there is a Ku Band Allocation. It
would have significantly better close-in resolution, but Max Range
over water would be the 10's of miles.

There is also a Marine Radar Frequency Allocation in the 5.46 - 5.56 Ghz
Band, and I have never seen a Marine Radar on this Band, either, however
this band is shared with the Aviation Radio Service, and there are
Aircraft Radars that do use this Frequency.

Radar Transponders in the Maritime Mobile Radio Service are licensed
under CFR47Part80, and the technical details for them can be found at
80.375 (d), and (e). They receive Radar emissions from Marine Radars,
and then add a predetermined Delay, and then Transmit a very large
Return Signal back, which shows up on the interrogating Radar Screen
as a VERY BIG TARGET. Radar Transponders are a separate device, and
are not part a Marine Radar, fitted on a vessel. They are REQUIRED
to be fitted to most classes of SOLAS REQUIRED Vessels. They also are
not cheap. Last time I looked, the cheapest one I saw was $1400US, and
that was some years back.

--
Bruce in alaska
add path after fast to reply

On Sep 20, 10:05 am, Bruce in alaska wrote:
In article
,
Two meter troll wrote:

some actually change the
emitter angle to give better returns at these ranges.

can you give us a Model Number of a Marine Radar that does the above?

--
Bruce in alaska
add path after fast to reply

nope I only know that they were Sperry's and i had to go up to the
dome to make sure the adjustment arms where working when i couldn't
find a deck hand. My first and second mates being scared ****less of
heading into the rigging (academy boys). when we un moth balled the
ship in spring the sounds of my yelling for the mate to change the
ranges could be heard in Greenland.
I am no radar tech however Sperry kindly gave us several procedure
sheets (about the size of the LA phone book) to guide us through. the
same systems we had up north where in place on all the ships i was on
for that company but i didn't have to mess with most of them. I do
recall that we had to import the techs directly from Sperry.

i was trying to look up the info you wanted but cant get onto the
Sperry web site; it seems it wont load.

Boeland wrote:
hpeer wrote:
Two meter troll wrote:
On Sep 18, 5:33 pm, wrote:
On Sep 18, 7:39 pm, "Wilbur Hubbard"
wrote:



wrote in message
...

: If someone has unlimited electrical power, is he likely to keep his
: Radar on all the time when he is far offshore? Offshore, far from
: anything else with a functioning radar system, what would prevent
: someone from detecting a sailboat before a collision. Assume clear
: weather.
Stupid question, I'm afraid. This is from the 72 COLREGS
INTERNATIONAL-
Steering and Sailing Rules
RULE 7
Risk of Collision
(a) Every vessel shall use all available means appropriate to the
prevailing
circumstances and conditions to determine if risk of collision
exists. If
there
is any doubt such risk shall be deemed to exist.
(b) Proper use shall be made of radar equipment if fitted and
operational,
including long-range scanning to obtain early warning of risk of
collision
and
radar plotting or equivalent systematic observation of detected
objects.
In clear language if you have operational radar it must be used when
underway.
I hope this helps.
Wilbur Hubbard
Wilbur, you are a dumbass. I asked because this did happen. The
question is why it happened.
Would someone far offshore turn off his radar if he had unlimited
power?
What would keep a radar from seeing an approaching sailboat. The
sailboat had right of way but neither vessel had a lookout. The boat
with radar may or may not have had it on. Weather was clear and seas
were said to be 4-6'.
Related question, if the person(s) on the radar equipped boat had his
radar on and it gave an indication of a target on a specific bearing
but every time the person looked outside he did not see anything,
would he maybe think his radar was malfunctioning and ignore it
I see from ads that radars have different modes for "offshore",
"nearshore", "harbor". What do these modes do?

IME sail boats are hard to see from some angles due to much of the
reflective bits being down in the boat.
however i would ask how large the boats where?
if a ship is sailing around and has his radar set correctly he ought
to be able to see most boats signatures. Sea clutter can be a problem
but IMO its not to difficult to tune out most clutter. you watch for
the returns that are somewhat constant and use your glasses to
confirm. it is not standard practice to shut down radar when out of
the common sea lanes in fact on really big ships it is foolish, not
only can high end radars read known ships and let you know who it is
but some have a tracking system for up to 140 targets which it assigns
by signal strength and repetition.

I have never missed a sail boat with one of these systems (not saying
it cant happen). fact of the matter is that i have seldom missed even
floating logs and i can tell you that they work like a dream for pack
ice (two other things that tend to get lost in the clutter.)

most of the Modes the radar manufacturer's are touting are power
settings, long, medium or short range. some actually change the
emitter angle to give better returns at these ranges. Sounds to me
that both ends of this accident have fault. there should have been
watches on both boats.

my 2 cents


Two Meter,

I thought that was a really good reply. I would add a couple of things.

One is that reading a radar display is a bit of art and not all have
either the skill (desire/drive) to acquire.

I have seen radars malfunction and it is not always apparent. I got
severely embarrassed once by missing an aircraft carrier from a C-130.
I had the gain set to not see sea return and the gain drifted off even
further without my knowledge.

I bought a "blipper" or transponder for off shore runs. I don't have
unlimited power but it is "helpful" to a shorthanded sailor to have
the blipper alarm on. For those who may not know a transponder will
give you an alarm and send a large signal to the ship with the radar.

Thanks again.
Knowing nothing about radars and transponders could you tell us what
brands are there and how they function. Do they need to be attached to
a radar or standalone and do they respond only to Search and Rescue
radar signals?
Thanks

I have a "see-me" that I bought second hand for a few hundred.

http://www.sea-me.co.uk/

Also, here is a link about reflectors, including see-me, that I have not
yet digested.

http://www.panbo.com/archives/2007/0...ally_work.html

In article
,
Two meter troll wrote:

On Sep 20, 10:05 am, Bruce in alaska wrote:
In article
,
Two meter troll wrote:

some actually change the
emitter angle to give better returns at these ranges.

can you give us a Model Number of a Marine Radar that does the above?

--
Bruce in alaska
add path after fast to reply

nope I only know that they were Sperry's and i had to go up to the
dome to make sure the adjustment arms where working when i couldn't
find a deck hand. My first and second mates being scared ****less of
heading into the rigging (academy boys). when we un moth balled the
ship in spring the sounds of my yelling for the mate to change the
ranges could be heard in Greenland.
I am no radar tech however Sperry kindly gave us several procedure
sheets (about the size of the LA phone book) to guide us through. the
same systems we had up north where in place on all the ships i was on
for that company but i didn't have to mess with most of them. I do
recall that we had to import the techs directly from Sperry.

i was trying to look up the info you wanted but cant get onto the
Sperry web site; it seems it wont load.

Well No wonder, it was a Sperry Radar.... These pieces of JUNK haven't
been around the beach for a decade or so. Kind of like the Kelvin Hughes,
Radars, and the Decca's of the early 70's. Fair radars, for being Second
Generation, but not really relevant in todays world of 5th Generation
Marine Radars.

--
Bruce in alaska
add path after fast to reply

On Sat, 20 Sep 2008 17:35:41 GMT, Bruce in alaska
wrote:

Radar Transponders are a separate device, and
are not part a Marine Radar, fitted on a vessel. They are REQUIRED
to be fitted to most classes of SOLAS REQUIRED Vessels. They also are
not cheap. Last time I looked, the cheapest one I saw was $1400US, and
that was some years back.

Decades ago I watched general aviation adopt transponders. The price
went down and down. Not unlike computer equipment. So 1400 may be
high. I am thinking of adding radar to my 22 foot runabout. There is
one with a 18 inch antenna for about $800. I could add a hardtop, [or
is that hard dodger?], and mount all kinds of stuff on it. Lights,
horn, antennae of all kinds. Probably cost more than I payed for the
boat.

Casady