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Subject: RE: [worldcruising] Email Options When Cruising
From: Rick H Kennerly (nh2f@XXX.XXX)
Date: Wed Nov 06 2002 - 12:05:26 EST
If you're not a Ham, then SailMail is about the only other cost effective
choice for the budget cruiser. (the Ham version called WinLink/AirMail is
about the same speed, BTW).
The only other option for offshore work in the hinterlands is satellite.
Just the stabilized platform, if you could find a place to put it, would be
more than the cost of new engine, plus electronics.
Sailmail/Airmal work well, but there are limitations. It's sure not the
fast log-on lots of user kind of system you're used to.
This topic came up on the liveaboard list just last week. I've reposted a
piece I did for that discussion below:
-------------------------------------
It's not so much a throughput question but rather a connection question and
quality of connection question.
While Susan reports good luck with Sailmail, she's also sitting--in a radio
sense--right in the backyard of the antenna. But these systems are not "on
demand", multiple connect or token ring passing kinds of systems distributed
server systems. Instead, these radio e-mail systems these are one to one
transactions.
Down here in the Carib radio e-mail connections are pretty good for Sailmail
and Airmail (ham) all summer long, but wait until the cruisers return for
the winter season. In the radio e-mail business it's a one to one network
system. That means that the radio server can only serve one cruiser radio
at a time and each connected cruiser can have ~20 minutes connect time per
day (depending on the service rules). Plus there is no orderly queue,
take-a-number-and-wait, or sign-up sheet to be served next by the radio
server.
Instead, radio e-mail systems are like a teacher and a class of unruly
juvenile crickets. The teacher asks the question, "who has something he or
she wants to say?" and at each desk hands go up and the students all chirp,
"me, me. me, me, me." And from that confused mess the teacher selects a
student who then gets to occupy the teacher's undivided attention until that
student's time runs out or the student has nothing more to say. Of course,
this teacher isn't so bright, so he selects the loudest signals first
(mostly because he can't hear the weaker, more distant signals through the
clutter). You can see where I'm going with this...
The farther from the main antenna you are (leaving atmospherics out of this
for the time being) or the weaker your signal is and the more competition
there is for the server radio's undivided attention, the longer you'll have
to wait. During the winter here on Puerto Rico, I've spent 12-hours or more
flipping around from "server" to "server" and frequency to frequency trying
to be heard and get a connect.
Not only that, but when you do get a connect, not everyone in the class is
waiting for the teacher to finish with you but is busy chirping, "me, me,
me, me" all the time you're computer is trying to talk, seriously degrading
your throughput because of all the "repeat" packets being sent. Then there
are commercial radio operators on big ships running enormous linear
amplifiers that put out 5 times the power of any Ham or Marine SSB unit.
All in all, for cruiser to cruiser contact, voice SSB or cruising HAM nets
deliver much more information much more efficiently. Of course, aren't you
going cruising to get away from all that?
Rick Kennerly, NH2F
Rick the Mouseherder
Xapic, Westsail 32
Cabo San Juan, Puerto Rico
www.mouseherder.com/xapic
www.westsail.org
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