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.

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

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?

On Thu, 18 Sep 2008 16:27:23 -0700 (PDT),
wrote:

If someone has unlimited electrical power, is he likely to keep his
Radar on all the time when he is far offshore?

Yes

Offshore, far from
anything else with a functioning radar system, what would prevent
someone from detecting a sailboat before a collision. Assume clear
weather.

High winds - sea clutter - failure to keep a proper radar watch or
lookout.

On Thu, 18 Sep 2008 16:27:23 -0700 (PDT),
wrote:

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.

Sailboats are notoriously poor reflectors. Even with RADAR reflectors
mounted on the mast, they don't always give much of a return.

Far offshore and away from known routes, it's usual to put the RADAR
on the "Watch" setting, which cycles it between standby and transmit
modes. You can set it to wake up and take a look around every 10
minutes, 20 minutes, whatever you want. This is a pretty standard
feature on most RADARS that you find on recreational vessels.

RADAR doesn't use nearly as much power as you seem to think. I sure
don't have unlimited electrical power on my sailboat with a 9.9 hp
outboard alternator as my only battery charger. I still use my RADAR
a lot. I just don't leave it in transmit mode when I'm not looking at
it.

On Sep 18, 10:01 pm, wrote:
On Thu, 18 Sep 2008 16:27:23 -0700 (PDT),
wrote:

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.

Sailboats are notoriously poor reflectors. Even with RADAR reflectors
mounted on the mast, they don't always give much of a return.

Far offshore and away from known routes, it's usual to put the RADAR
on the "Watch" setting, which cycles it between standby and transmit
modes. You can set it to wake up and take a look around every 10
minutes, 20 minutes, whatever you want. This is a pretty standard
feature on most RADARS that you find on recreational vessels.

RADAR doesn't use nearly as much power as you seem to think. I sure
don't have unlimited electrical power on my sailboat with a 9.9 hp
outboard alternator as my only battery charger. I still use my RADAR
a lot. I just don't leave it in transmit mode when I'm not looking at
it.

Surely the sailboat would give some radar return before the collision
(assuming it is on). In clear conditions, what might cause somebody
to disregard a radar alarm? How often do radars return false echoes
in calm conditions? Just how "invisible" are most sailboats, say 30'
to radar without a reflector? Would objects such as downriggers or
other things aloft on the boat with radar cause false returns?
I see that some radars can be set to look only in a specified arc and
ignore things elsewhere. I assume that is to avoid looking behind and
concentrate on looking ahead. Why does this matter? Are false
returns enough of an issue to cause someone to only look ahead?

wrote:
On Sep 18, 10:01 pm, wrote:
On Thu, 18 Sep 2008 16:27:23 -0700 (PDT),
wrote:

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.
Sailboats are notoriously poor reflectors. Even with RADAR reflectors
mounted on the mast, they don't always give much of a return.

Far offshore and away from known routes, it's usual to put the RADAR
on the "Watch" setting, which cycles it between standby and transmit
modes. You can set it to wake up and take a look around every 10
minutes, 20 minutes, whatever you want. This is a pretty standard
feature on most RADARS that you find on recreational vessels.

RADAR doesn't use nearly as much power as you seem to think. I sure
don't have unlimited electrical power on my sailboat with a 9.9 hp
outboard alternator as my only battery charger. I still use my RADAR
a lot. I just don't leave it in transmit mode when I'm not looking at
it.

Surely the sailboat would give some radar return before the collision
(assuming it is on). In clear conditions, what might cause somebody
to disregard a radar alarm? How often do radars return false echoes
in calm conditions? Just how "invisible" are most sailboats, say 30'
to radar without a reflector? Would objects such as downriggers or
other things aloft on the boat with radar cause false returns?
I see that some radars can be set to look only in a specified arc and
ignore things elsewhere. I assume that is to avoid looking behind and
concentrate on looking ahead. Why does this matter? Are false
returns enough of an issue to cause someone to only look ahead?

How far offshore and how far from known routes? Far enough and many
don't even turn on lights at night let alone radar!
G

On Thu, 18 Sep 2008 19:21:19 -0700 (PDT),
wrote:

On Sep 18, 10:01 pm, wrote:
On Thu, 18 Sep 2008 16:27:23 -0700 (PDT),
wrote:

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.

Sailboats are notoriously poor reflectors. Even with RADAR reflectors
mounted on the mast, they don't always give much of a return.

Far offshore and away from known routes, it's usual to put the RADAR
on the "Watch" setting, which cycles it between standby and transmit
modes. You can set it to wake up and take a look around every 10
minutes, 20 minutes, whatever you want. This is a pretty standard
feature on most RADARS that you find on recreational vessels.

RADAR doesn't use nearly as much power as you seem to think. I sure
don't have unlimited electrical power on my sailboat with a 9.9 hp
outboard alternator as my only battery charger. I still use my RADAR
a lot. I just don't leave it in transmit mode when I'm not looking at
it.

Surely the sailboat would give some radar return before the collision
(assuming it is on). In clear conditions, what might cause somebody
to disregard a radar alarm? How often do radars return false echoes
in calm conditions? Just how "invisible" are most sailboats, say 30'
to radar without a reflector? Would objects such as downriggers or
other things aloft on the boat with radar cause false returns?
I see that some radars can be set to look only in a specified arc and
ignore things elsewhere. I assume that is to avoid looking behind and
concentrate on looking ahead. Why does this matter? Are false
returns enough of an issue to cause someone to only look ahead?

As I said, sailboats are often invisible to RADAR. Sometimes even a
RADAR reflector isn't enough to make them show up. This is a
universally well known fact of life.

The other factor is that reading and operating RADAR is not like
watching something literal on television. It's closer to knowing how
to read a medical xray. It takes knowlege coupled with a lot of
experience to have even an approximate idea of what you are looking
at. I use my RADAR in perfectly clear vis conditions in my home waters
almost all the time, just to keep those skills sharp. One thing you
learn is how retruns from different types of object appear. Most
navigation aids, for example, now have RADAR reflectors built into
their design. It increases the power of the return from those buoys
and makes them look like larger objects than they really are. Bear in
mind that they add thiose reflectors, even though the nav aids are
made of steel, and show up pretty well without the reflectors. It
helps to make them stand out on the screen. Slow moving sailboats may
appear to be stationary objects, even if they do give a return.

In other words, this isn't nearly as simple and cut&dry as you seem to
imagine.

On Thu, 18 Sep 2008 19:21:19 -0700 (PDT),
wrote:

I see that some radars can be set to look only in a specified arc and
ignore things elsewhere. I assume that is to avoid looking behind and
concentrate on looking ahead.

That is called blanking and is used to blank out the RADAR as it tries
to sweep through parts of your own boat that may be in the way. If you
have a pole mounted RADAR on the stern, for example, you set it to
blank as it passes the metal mast that is 20 feet away.

Not looking behind you would be a serious error in operation of your
boat. You need to stay aware of all 360 degrees.

On Thu, 18 Sep 2008 19:21:19 -0700 (PDT),
wrote:

Surely the sailboat would give some radar return before the collision
(assuming it is on). In clear conditions, what might cause somebody
to disregard a radar alarm? How often do radars return false echoes
in calm conditions? Just how "invisible" are most sailboats, say 30'
to radar without a reflector? Would objects such as downriggers or
other things aloft on the boat with radar cause false returns?
I see that some radars can be set to look only in a specified arc and
ignore things elsewhere. I assume that is to avoid looking behind and
concentrate on looking ahead. Why does this matter? Are false
returns enough of an issue to cause someone to only look ahead?

A lot depends on sea conditions, the quality of the radar and the
skill/diligence of the watch stander. Seas of 4 to 6 feet are enough
to obscure small boats of all types until they are very close. The
alarm feature is not present on all radars, and even if it exists, may
not be in use. I have a fairly decent Furuno with all of the modern
features and 4 to 6 foot seas generate enough clutter that the alarm
becomes almost useless for spotting smaller boats. More effective are
the electronic signal averaging functions but that requires constant
eyes on the screen and experience/skill interpreting the results.

Not all radar reflectors are equally effective, and they have to be
properly mounted and oriented to be effective at all. The small
tubular units are nearly useless, best are the large round ones hung
in the so called "catch rain" position.

If you are offshore in a small boat assume that you are *not* being
seen, and be prepared to take effective evasive action regardless of
your percieved right-of-way.