I installed a Milltech SR161 and an antenna splitter on BlueJacket just
before moving it from the Chesapeake to Ft. Lauderdale and I must say that
I was very happy with the performance. My VHF antenna is on top of my 60'
mast and most of the time I saw ships at 40 miles or less. On a less
frequent basis I would see ships at 40-60 miles away and I even saw a
cruise ship at 88 miles away. I was amazed and I realize that it must have
been some strange skip to hear a vessel so far away. In areas like
Norfolk, Charleston and Ft. Lauderdale I regularly had 50+ targets that I
was tracking.

The "no AIS" alarm was a real pain in fringe ares where a single ship's
signal would fade in and out and the alarm would keep going off. That has
to be fixed.

I was using this on a RayMarine C-80 and the biggest problem that I had was
with false "dangerous target" alarms. I have my MARPA/AIS alarm radius set
to 20 miles, such that if a target is within that radius an alarm will go
off. The problem is that all targets, even those at anchor or moored,
cause an alarm. I understand the logic behind this, but in my mind these
are false alarms. I also had problems with some targets generating
continuous alarms, causing me to shut off the AIS alarm. I reported this
to RayMarine and they say that a new version due out in Q1 of 2007 should
address these problems.


Despite the problems that I saw, I wouldn't be without this. MARPA on a
small sailboat underway can't begin to compare with the accuracy of AIS and
its fun to see information about targets such as names, size, type and
destination. I do look forward to getting a transponder when the prices
come down as I want the other vessels out there to see me as well as I see
them.

-- Geoff

The problem is that all targets, even those at anchor or moored,
cause an alarm. I understand the logic behind this, but in my mind these
are false alarms.

Well, if you're moving then their being anchored is still a problem.

I can also understand why, from a liability perspective, they'd still want
to issue an alarm for them.

But yeah, I'm with you on wishing the alarm function was a little smarter.
Or that the sound used for alarms was configurable instead of just one for
all of them.

I agree 100% with this text:

Well, if you're moving then their being anchored is still a problem.

I can also understand why, from a liability perspective, they'd still want
to issue an alarm for them.

If you are aproaching a harbor at night and you caould fall a sleep you
would not like to be warned by your AIS/Plotter when you are going in
direction of a big ship that is anchored.... or not?

Pascal


Bill Kearney escreveu:

The problem is that all targets, even those at anchor or moored,
cause an alarm. I understand the logic behind this, but in my mind these
are false alarms.

Well, if you're moving then their being anchored is still a problem.

I can also understand why, from a liability perspective, they'd still want
to issue an alarm for them.

But yeah, I'm with you on wishing the alarm function was a little smarter.
Or that the sound used for alarms was configurable instead of just one for
all of them.

At night, in a large body of water, every vessel appears to be either
at anchor (minus any type of speed boat or ferry). This is especially
true if the boat is moving directly away from you or towards you.
MARPA capabilities on RADAR help with this somewhat.

The AIS ability to see ALL vesels and know with certainty if they are
at anchor or steaming, and at what heading and speed takes much of the
guess work out of the equation of safety.