Opinions on Radars
 

I had a JRC 1000 on my first boat and now I am restoring a 43 Endeavour
ketch and it is time to think about radars. The JRC was a nice unit but
woefully underpowered. I would like to see out 8 to 10 miles with the
radome mounted 20-30' up the mizzen. I know that the 4kw will give more
power out and thus burn thru in foggy conditions but most of the 4kw units
have the big displays. Everyone on this group knows the drill...what will
give me the biggest bang for the buck with the best reliability amd a thin
small display.
Thanks
Bruce

--
Shield Finishes and Nauticoat Marine Finish Systems
www.shieldfinishes.com

Bruce on horizon wrote:
I had a JRC 1000 on my first boat and now I am restoring a 43 Endeavour
ketch and it is time to think about radars. The JRC was a nice unit but
woefully underpowered. I would like to see out 8 to 10 miles with the
radome mounted 20-30' up the mizzen. I know that the 4kw will give more
power out and thus burn thru in foggy conditions but most of the 4kw units
have the big displays. Everyone on this group knows the drill...what will
give me the biggest bang for the buck with the best reliability amd a thin
small display.

The RayMarine equipment lets you mix and match the displays and the
domes so you get what you need now, and upgrade later. BTW, the radar
horizon is about 7 miles from a transmitter 30 feet up. Large targets
will of course be seen at a larger distance, but I can't say that I've
had any problem with my low power Raytheon, and I cruise in Maine and
Cape Cod.

I would like to see out 8 to 10 miles with the
radome mounted 20-30' up the mizzen.

Hi Bruce,

As Jeff says, your radar will not be able to pick up small targets past
your visible horizon (about 6.3 nm according to Bowditch). You will be
able to pick up big, tall contacts further out, but that's about it.

I'd stick to a 1.5 to 2 kw radar if I were you. Higher power doesn't
"burn" through anything, including fog, and I think 4 kw is over kill
for what you'll be doing. In fact at the short ranges you'll be
operating at, the higher power will probably be a disadvantage. The
RayMarine stuff looks pretty nice and has alot of nice features (like
color and MARPA (their adaptation of ARPA)). But I'd go with a small
Furuno if you can afford it or another JRC if you're on the cheap. Just
my biased opinion though. Walk around the docks and see what the
smaller commercial fisherman in your area use. They tend to only get
stuff that works, why not do the same?

Just remember, if you get too fancy a radar, chances are your attention
will be fixated on that fancy screen and not your main navigation tool:
your "Mark I Mod II Eyeballs" ;-)

Hope this helps,

Paul

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On Sun, 13 Feb 2005 17:20:53 -0500, "Bruce on horizon"
wrote:

I would like to see out 8 to 10 miles with the
radome mounted 20-30' up the mizzen. I

Sidebar question: Am I woefully ignorant on radar implementation or am
I correct in assuming that a target heading directly for one's bow
would be invisible to a mizzen mounted radar due to the three-to-four
degree "screen" of the main mast directly ahead?

Or am I missing something? Why the mizzen (aside from its convenience
and the fact few people use a mizzen stays'l, so nothing to hook the
radome or mount).

R.

rhys wrote:
On Sun, 13 Feb 2005 17:20:53 -0500, "Bruce on horizon"
wrote:

I would like to see out 8 to 10 miles with the

radome mounted 20-30' up the mizzen. I


Sidebar question: Am I woefully ignorant on radar implementation or am
I correct in assuming that a target heading directly for one's bow
would be invisible to a mizzen mounted radar due to the three-to-four
degree "screen" of the main mast directly ahead?

Or am I missing something? Why the mizzen (aside from its convenience
and the fact few people use a mizzen stays'l, so nothing to hook the
radome or mount).

R.

Quite possibly, IF you where an expert helmsman at all times.

otn

BTW I hate small displays. I'd get the biggest one possible.
Also, don't get hung up on the "height of eye" distance capabilities of
your radar ..... your "HE" may only say 6ish miles, but you'll be able
to see a whole bunch of stuff beyond that.

otn

I am not a schill for Practical Sailor (subscription newsletter), nor
do I play one on TV, but I do find their articles generally useful,
educational and informative. They did a piece on 'Entry Level LCD
Radar' in September '04, the preamble to which you can see he

http://www.practical-sailor.com/pub/...es/5003-1.html

MW

Jeff Morris wrote:
Bruce on horizon wrote:

I had a JRC 1000 on my first boat and now I am restoring a 43
Endeavour ketch and it is time to think about radars. The JRC was a
nice unit but woefully underpowered. I would like to see out 8 to 10
miles with the radome mounted 20-30' up the mizzen. I know that the
4kw will give more power out and thus burn thru in foggy conditions
but most of the 4kw units have the big displays. Everyone on this
group knows the drill...what will give me the biggest bang for the
buck with the best reliability amd a thin small display.


The RayMarine equipment lets you mix and match the displays and the
domes so you get what you need now, and upgrade later. BTW, the radar
horizon is about 7 miles from a transmitter 30 feet up. Large targets
will of course be seen at a larger distance, but I can't say that I've
had any problem with my low power Raytheon, and I cruise in Maine and
Cape Cod.

I've had minor second thoughts on this after checking the specs. In the
"old days" more powerful domes were heavier and used more power - that
is not the case now - the 4kW Raymarine dome only weighs a few pounds
more and uses 1 or 2 Watts more juice.

I'm still not sure of the value for long distance viewing, but the high
power dome will have finer resolution, so that a pair of channel buoys
will be resolved as two targets further away with the more powerful
unit. Navigation is easier, since coastlines will more closely resemble
the chart. However, this takes a lot of practice and you're better off
relying on a good gps.

The downsides of the large unit is almost double the cost (a $1000
premium on the RayMarine list) and a much larger dome (an issue for
those trying to hide the dome from the jib).

Stay away from Raymarine! Since they separated from Raytheon, they're
turning into cheap junk. Stick with Furuno.

--


Keith
__
"Usually, terrible things that are done with the excuse that progress
requires them are not really progress at all, but just terrible things." -
Russell Baker
"Bruce on horizon" wrote in message
...
I had a JRC 1000 on my first boat and now I am restoring a 43 Endeavour
ketch and it is time to think about radars. The JRC was a nice unit but
woefully underpowered. I would like to see out 8 to 10 miles with the
radome mounted 20-30' up the mizzen. I know that the 4kw will give more
power out and thus burn thru in foggy conditions but most of the 4kw units
have the big displays. Everyone on this group knows the drill...what will
give me the biggest bang for the buck with the best reliability amd a thin
small display.
Thanks
Bruce

--
Shield Finishes and Nauticoat Marine Finish Systems
www.shieldfinishes.com

On Mon, 14 Feb 2005 04:22:24 GMT, otnmbrd
wrote:

rhys wrote:

Sidebar question: Am I woefully ignorant on radar implementation or am
I correct in assuming that a target heading directly for one's bow
would be invisible to a mizzen mounted radar due to the three-to-four
degree "screen" of the main mast directly ahead?


R.

Quite possibly, IF you where an expert helmsman at all times.

Agreed, and I know what you are getting at. But if seas are flat, wind
is calm, and you are on a misty seaway at dusk/dawn motoring at five
knots under autopilot, I can see where a trawler or small frieghter
doing the same on a reciprocal course would be nearly invisible to you
simply due to the fact that your radar's proximity alarm or "range
guard" or whatever they call it would not go off until the ship on the
collision course was on top of you...solely due to the mizzen
placement.

A person on watch on a calm, foggy night (say a 75 foot high bank of
fog, giving the impression it's clear "enough" overhead, but miserable
all around) *might( hear engine noise or see a dim glow. But with the
terrible watch-keeping on commercial traffic these days, I wouldn't
count on being seen, either.

I suppose the other side of the equation is that a mainmast mounted
radome on a ketch has poor coverage aft, meaning that a ship
overtaking you from dead astern would also be hard to notice in such
conditions, particularly over your own exhaust note.

But such conditions are exactly when one would use radar, no?

R.

rhys wrote:
On Mon, 14 Feb 2005 04:22:24 GMT, otnmbrd
wrote:


rhys wrote:

Sidebar question: Am I woefully ignorant on radar implementation or am
I correct in assuming that a target heading directly for one's bow
would be invisible to a mizzen mounted radar due to the three-to-four
degree "screen" of the main mast directly ahead?


R.

Quite possibly, IF you where an expert helmsman at all times.


Agreed, and I know what you are getting at. But if seas are flat, wind
is calm, and you are on a misty seaway at dusk/dawn motoring at five
knots under autopilot, I can see where a trawler or small frieghter
doing the same on a reciprocal course would be nearly invisible to you
simply due to the fact that your radar's proximity alarm or "range
guard" or whatever they call it would not go off until the ship on the
collision course was on top of you...solely due to the mizzen
placement.

Doing some geometry, the mast blocks about a 1 degree angle from the
mizzen. The horizontal beam width of the low power units is about 5
degrees, so most of the energy will get past the mast. The higher power
units have a tighter beam and thus would loose a bit more, though the
Ray 4kW dome is still at 4 degrees. The high power, open arrays tend to
get down below 2 degrees, so they may get blocked more. Frankly, I
doubt this is really a problem.

On the other hand, a jib that fouls the radar on every tack is a major pain!

....


I suppose the other side of the equation is that a mainmast mounted
radome on a ketch has poor coverage aft, meaning that a ship
overtaking you from dead astern would also be hard to notice in such
conditions, particularly over your own exhaust note.

My radar doesn't seem to have a problem seeing "around" the mast. I
suppose the close proximity of the mast might absorb some energy, but I
haven't noticed it.

But such conditions are exactly when one would use radar, no?

This is why I avoid going in a straight line :-)