Some of this is old, some recent, maybe relevant.

We put a Raytheon R41XX with MARPA and KVH compass (supplied by Raytheon for
the radar) on Swee****er (Swan 57) in 1995. The MARPA would not maintain
lock in any kind of serious offshore conditions -- downwind in the trades
for example -- as the yawing was too great and update rate not fast enough.
As a practical matter, it was usable only in quite calm water; as a result
we rarely even tried to use it.

I have spent a fair amount of time at boat shows looking hard at this
question, as we want working, reliable, ARPA on Fintry. Both Simrad and
Furuno have no question that a stabilized flux gate will not do the trick,
that we need to use a full gyro ($10k) or, now, a GPS compass ($3k).
Raymarine is more equivocal, as they "think" that the compass you cite will
work.

All of this is complicated by the fact that Fintry is steel, and while the
compass would sit above an aluminum wheelhouse, 150 tons of steel 15-50 feet
away won't help it.

At the moment, for what it worth, my choice for the radar is Furuno (12kw,
six foot antenna), with the Furuno GPS compass providing heading
information.

And, also for what it's worth, our R41XX went down in Australia. The repair
was done by an authorized dealer, well within warranty, and I had to pay
full boat for the repair -- all parties involved pointed their finger at the
others and, in effect, said, "The other guy will pay....."
Furuno, I am told by several dealers, is better about warranty out of the
USA.

--
Jim Woodward
www.mvFintry.com


..
"BOEING377" wrote in message
...
I am planning to install a Raytheon radar R 70RC plus CRT
display/controller.which has a MARPA feature which tracks 10 targets. How
well
does this MARPA feature work if you have a stable fast reacting heading
ref
(KVH gyro stabilized flux gate in my case)? I may use only the 2 KW
transceiver which has so-so angular resolution. I am mostly interested in
tarcking boats that are within 3 miles of my position. I got feedback from
one
user who said his worked great. He had the Ray smart heading sensor which
is a
flux gate with a rate gyro. Anyone else using this Ray MARPA feature?
Comments?
Anyone out there using HSB to have two radar displays working off one
transceiver? Any glitches?

On Mon, 10 Nov 2003 18:45:31 -0500, "Jim Woodward" jameslwoodward at
attbi dot com wrote:

All of this is complicated by the fact that Fintry is steel, and while the
compass would sit above an aluminum wheelhouse, 150 tons of steel 15-50 feet
away won't help it.

Sorry you're so far away and our degaussing range and degausser are
all gone when they closed the Charleston Naval Shipyard, Jim. I used
to know someone who could neutralize Fintry's field for a few beers or
a harbor cruise. It would have been fun to see her plotted magnetic
field all printed out. That thing was so sensitive it could detect an
out-of-place electronics tool box in a minesweeper....and tell you
where you lost it!

The degausser is still right next to the marina at the south end of
the old base. I've been inside its amazingly intense field many
times. Those a big cables laying across the deck and even then they
got really HOT!



Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"