Normally I defer to your wisdom, but a few points he

Peter Bennett wrote:
On 23 Jun 2005 08:02:14 -0700, wrote:
....


Do they have a "warm-up" time?

The three models I've used had a 90 second warm-up. They also have a
"standby" mode that turns off the transmitter, but leaves the
magnetron warm.


Note that magnetron life (which is a finite resource) is not used up
by standby time.



Do you use it continously?


I usually do. New users should certainly use the radar in good
visibility until they are confident in identifying targets. Things
don't always appear as you might expect.


Likewise. A missing part of this discussion is that the novice will
only be able to make marginal use of a radar. It takes some training
(at least several hours, ideally more) and a lot of practice to be
proficient. Even then, when its needed the most (in heavy fog for
instance) the helmsman it likely preoccupied doing basic navigation,
and the first watch should be ears and eyes. The only way that radar
is useful is if there is a dedicated radar watch, or if the helmsman
is quite experienced.


How far away will it detect:
1. A ship

Over 5 miles

This would be a minimum. If the radar is mounted 20 feet up (this if
often cited as the optimal height, though its open for discussion) the
radar horizon is 5 miles. Thus, an object that has a good return at
twenty feet up it theoretically visible at 10 miles, though this might
be pushing the limits of a small unit.



2. A buoy with a corner reflector

1 - 2 miles, I think.

Jeeze, you can see a larger buoy at 2.5 miles! Radar should see them
a bit further off. Usually when I first spot a distant buoy I use the
radar to tell me if that's my waypoint or just a boat.




3. A small sailboat with radar reflector

about the same

Again, the theoretical limit is about 10 miles, but in practice its
less than half that. And remember, half the reflectors are junk.



4. A small sailboat WITHOUT radar reflector

varies


Under 5 miles there should be enough metal visible to give a return,
but over that distance, you're only seeing a few feet of mast.



How does chop affect its performance?

may obscure close targets - but most sets have a "Sea Clutter" control
that should help.

Chop is not an big issue, however ...

The beam width of small radars is +-12.5 degrees. Thus, if you're
heeling 15 degrees (assuming no leveling device) you're seeing almost
nothing to windward or leeward. If you're bouncing that much, your
signal is intermittent. And if you're a powerboat at speed with the
bow raised 15 degrees, you could be blind in front!



Does bad weather affect it?

Heavy rain will show up, and may obscure targets in the rain (but it
takes _very_ heavy rain to do that.)


Yes, but the heavy rain situation is one of the times you need the radar.