rhys wrote in
:

Now, if I can just figure out how to put a windvane AND davits behind
a mizzen mast....G

R.


B&G Pilot has "wind mode" to track the wind with the autopilot. Works
great in that mode, too.

No cure for the davits if your mizzen boom is too low.....

"Larry W4CSC" wrote in message

Ah, but you have another problem in the fog. The higher the antenna, the
further away the target will disappear as the target approaches the boat!
You won't see the bouy 8 miles away with the antenna down low, but you
WILL
see the bouy in the fog a LOT closer to the boat as you, hopefully, pass
it.

Traveling at Mach 1, I'd understand having more range. But, traveling at
6
knots I'd rather see that target two boatlengths off the port bow with a
lower-down antenna....wouldn't you?

I have to wonder how serious a problem this really is.
For instance, if I can run between two buoys spaced 300' with a scanner
that's over 100' in the air and watch them pass down my side, how much
difference can there be with a small boat and a scanner placed 30' up,
unless you are totally crowding the buoy to one side (not good).
Also, by that point, if you lose sight of the buoy, you should have all
ready changed your concentration to some new point or reference, ahead.

otn

On Tue, 15 Feb 2005 04:44:49 GMT, Larry W4CSC wrote:


Furuno? Anyone had water destroy a Furuno radar dome??

OK, crap construction drives me nuts, particularly when it's something
(like a radar) which MUST spend its working life out in the elements.

Assuming the radar itself isn't absolute crap...like that "Mars Bar"
radar the Brits made 25 years ago, say...what is *your* radar of
choice for durability? 'Cause once I go up the mast, I don't want
anything short of a hurricane to cause damage to that radome...

My buddy swears by his old Kodan CRT unit, but he's got a big ketch
and more room and power than most people to play with. The thing is a
toaster-sized box bolted to his coaming, and it takes skill to use it,
but if you can learn that skill, it's accurate as hell.

R.

On Mon, 14 Feb 2005 14:38:03 -0500, Jeff Morris
wrote:


Does that sum it up?

Yup. After sailing a sistership with the radar mounted high on the
mast, I mounted mine below the baby stay, and never regretted it.

Good. Thanks. One day I hope to use this information wisely.


Reason I'm asking is that steel ketches look good to me on a number of
levels.

Now, if I can just figure out how to put a windvane AND davits behind
a mizzen mast....G

The windvane should go high on the mizzen, as on my friends boat:
http://www.sv-loki.com/Moonshadow/Pg22.jpg

Note that the davits are behind, and also serve as a good place for
solar panels.

Agreed, but I didn't mean windvane as in wind generator, but as in
"mechanical self-steering" like this: http://www.voyagerwindvanes.com/

I can't determine how THAT would work on a ketch, with or without
davits.

R.

On Mon, 14 Feb 2005 21:07:37 GMT, Dan Best
wrote:

I dissagree.
The antenna that the energy is radiating off of is much wider than the
mast, so while some of the energy is reflected and scattered, most of it
just flows right on past. The reverse happens with the reflected
energy. As a result, the targets are weaker, but should still be there.
If this were not the case, then whenever you had a mast mounted radar,
everything in a fairly wide cone behind you would be invisible and this
is obviously not the case.

Thanks to you and Otnmbrd for these answers.

On a related topic, make sure that you mount the display where it can be
seen by the helmsman. A friend of mine has it mounted where it can only
be seen at the nav station and having played radar officer calling up
instructions to the helm on a foggy night in SF Bay while dodging
freighters, I'm here to say that that's not how you want to set it up.

It would tend to "compound errors", certainly. I've installed
something on my current boat, however, that I haven't seen before. I
got a gooseneck armature from an old draftsman's flourescent light and
clamped it so that it swings into the companionway. It can be lashed
in position with shock cord, if needed, but usually the friction knobs
do the trick.

On the armature I've secured a handheld GPS on "ship's power" (a 12 V
cigarette lighter style adapter). This means I can reference the GPS
quickly without using my hands, and without it being loose in the
cockpit, without eating batteries (they go through AAs in 2-3 hours of
continuous use), without losing "satellite lock" (because they are on
all the time and in the companionway can "see" enough sky).

Other advantages are (mostly) out of the weather (a ziplock bag will
do the trick here as well).

Of course, I have a tiller, which means I am standing most of the time
by the companionway near the winches and aft of the traveller on the
cabin-top.

I wonder, however, if my "armature idea" would be useful for any
similar devices, as opposed to a "hard-mount" at the wheel? If, for
instance, you had a 15" LCD panel and a wireless mouse, the panel
could be some distance away and still be readable.

R.

On Tue, 15 Feb 2005 04:54:14 GMT, Larry W4CSC wrote:

It's
more like a 2' diameter floodlight shining past the mast, illuminating the
target dead ahead, but probably with some loss of efficiency.
Thanks, Larry. I understand this now.

R.

rhys wrote:

It would tend to "compound errors", certainly. I've installed
something on my current boat, however, that I haven't seen before. I
got a gooseneck armature from an old draftsman's flourescent light and
clamped it so that it swings into the companionway. It can be lashed
in position with shock cord, if needed, but usually the friction knobs
do the trick.

I've seen this type of mount on many boats, though not using the
draftsman's armature. I think the catalogs have brackets intended to
swing out in the companionway.




On the armature I've secured a handheld GPS on "ship's power" (a 12 V
cigarette lighter style adapter). This means I can reference the GPS
quickly without using my hands, and without it being loose in the
cockpit, without eating batteries (they go through AAs in 2-3 hours of
continuous use), without losing "satellite lock" (because they are on
all the time and in the companionway can "see" enough sky).

Other advantages are (mostly) out of the weather (a ziplock bag will
do the trick here as well).

Of course, I have a tiller, which means I am standing most of the time
by the companionway near the winches and aft of the traveller on the
cabin-top.

I wonder, however, if my "armature idea" would be useful for any
similar devices, as opposed to a "hard-mount" at the wheel? If, for
instance, you had a 15" LCD panel and a wireless mouse, the panel
could be some distance away and still be readable.

My current boat, being a catamaran, has a powerboat-like helm station
with the radar mounted on a swinging arm to the side. My previous boat,
had a clever idea that might be of use to some - A hatch was mounted in
the bulkhead in the forward end of the cockpit, and the radar (a large
crt) was mounted on a shelf inside. Its a nice solution for a display
that is too large to mount on an arm. However, once you get used to
have the controls at the helm, its hard to see how you can properly use
a radar that isn't nearby.

On Tue, 15 Feb 2005 04:44:49 GMT, Larry W4CSC wrote:


Isn't it amazing how 2,000 watts of peak RF power just appears from thin
air for only 1-2 watts more DC? Magic? Divine intervention? Maybe its
the printer stepper motor that turns the rubber band that drives the PC
board antenna array...??

Not sure about the merits of this beef.
A radar with a pulse repetition period of 1 millisecond, and a pulse
width of 1 microsecond has a peak power about a thousand times greater
than its mean power - and this is a standard feature of pulse
radars....

Brian Whatcott Altus OK

In article ,
rhys wrote:

On Tue, 15 Feb 2005 04:44:49 GMT, Larry W4CSC wrote:


Furuno? Anyone had water destroy a Furuno radar dome??

OK, crap construction drives me nuts, particularly when it's something
(like a radar) which MUST spend its working life out in the elements.

Assuming the radar itself isn't absolute crap...like that "Mars Bar"
radar the Brits made 25 years ago, say...what is *your* radar of
choice for durability? 'Cause once I go up the mast, I don't want
anything short of a hurricane to cause damage to that radome...

My buddy swears by his old Kodan CRT unit, but he's got a big ketch
and more room and power than most people to play with. The thing is a
toaster-sized box bolted to his coaming, and it takes skill to use it,
but if you can learn that skill, it's accurate as hell.

R.

Give me a Furuno, over any other third and fourth generation Radar OEM
and a Decca over any second generation Radar. First generation radars
were all crap, and the fifth generation is just now coming out, so no one
knows yet who has the best stuff.......

Bruce in alaska
--
add a 2 before @

In article . net,
"otnmbrd" wrote:

I have to wonder how serious a problem this really is.
For instance, if I can run between two buoys spaced 300' with a scanner
that's over 100' in the air and watch them pass down my side, how much
difference can there be with a small boat and a scanner placed 30' up,
unless you are totally crowding the buoy to one side (not good).
Also, by that point, if you lose sight of the buoy, you should have all
ready changed your concentration to some new point or reference, ahead.

otn

OTN, the Horozontal Beamwidth of your Commercial Maritime Radar is
significantly smaller than that of the units found on most Pleasure
type vessels. That makes a HUGH difference in the Target Discrimination
Ability between the two radars. Apples and Oranges, here.......


Bruced in alaska
--
add a 2 before @