[PUP] ARPA or AIS?

[Truelove39 at aol.com]

We  have both and I have to say that whereas Furuno's ARPA is better  than
nothing but it is problematic in high seas. In calm weather it is  flawless.
However, in big seas it can lose the target and acquire a wave and  then
transition back to the target unless quite far away in which case it will
simply
adopt a wave and follow it or sometimes jump from wave to wave. Also, we  need
to
change the "vector time" setting in order to prevent falseing in big  waves
from giving us wild variations in heading. Unless set for a  relatively long
time, a vector time setting you'd use in calm conditions for a  fast target is
far too short for a slow boat at five miles in big  seas.

OTOH,  AIS has proven dead on, and when there's a difference vis-a-vis ARPA
we know  which to trust!

Regards,

John
"Seahorse"



>Thinking  about Johns questions, a few weeks ago I was traveling with
another skipper  who had invested in Furuno's fantastic AIS system, but
had passed on adding  the ARPA card to his chartplotter/radar.  While
I'm a fan of AIS I think  an ARPA feature is much more valuable and
would be the first thing I'd buy  (or recommend).  I have used ARPA
hundreds of times and the Furuno  implementation is fantastic.  I was
really surprised how good it was  compared to the Nobeltec solution I
had on my Camano.  The nobeltec  software seemed to be running the
course analysis algorithm too fast,  resulting in wildly changing
course vectors.  It may also have been that  they didn't average the
selected target very well, accounting for the wild  course output.
Anyway the point is while AIS is great, I think ARPA is a  requirement
for passagemaking, while AIS is a "really nice to  have".

Scott Bulger, Alanui, N40II, Seattle WA


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