Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-02-2010, 07:49   #1
Registered User
 
SvenG's Avatar

Join Date: Oct 2009
Location: Mexico heading South
Boat: Ericson 39B - Senta II
Posts: 1,169
Abby's AIS Range ?

In her most recent blog entry ( Abby's Blog )Abby Sunderland states

Quote:
I just saw it on my AIS and it was 86 miles away
That seems like a very long distance (twice the nominal maximum) unless her's is satellite augmented ?

Did she read the AIS wrong or am I mistaken about the range capabilities or is there something else that I'm overlooking ?




-Sven
__________________

__________________
Senta II - http://www.Grenander.com/Senta_II/Blog/Blog.html
1977 Ericson 39B -- Hull # 216
SvenG is offline   Reply With Quote
Old 02-02-2010, 08:00   #2
Registered User
 
Hampus's Avatar

Join Date: May 2008
Location: Sweden
Boat: Between boats
Posts: 463
Images: 6
Send a message via MSN to Hampus
Under extreme conditions it's possible, but not likely.

/Hampus
__________________

__________________
http://adventureswithsyingeborg.blogspot.com/
On the way back to Sweden.
Hampus is offline   Reply With Quote
Old 02-02-2010, 08:14   #3
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,864
Images: 4
It's not that uncommon to receive AIS signals on the water at this range -- it happens quite often in my experience. It is definitely not something you want to depend on though. 10-20 miles is the norm. It depends on the weather.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 02-02-2010, 10:31   #4
Registered User
 
Jmolan's Avatar

Join Date: Dec 2007
Location: Mexico/Alaska/Oregon
Boat: 34' Searunner Tri
Posts: 712
This happens, we call them phantom hits. They are intermittent. Height of antennea is a big factor, and then a mtn. range can make a big difference. We have a "bowl" of a mtn. range in Alaska. When we are sailing by the bowl. we get 50 to 100 mile hits on ships.
__________________
Jmolan is offline   Reply With Quote
Old 02-02-2010, 18:23   #5
Registered User
 
bewitched's Avatar

Join Date: Sep 2009
Posts: 885
Images: 3
AIS is broadcast on VHF and like VHF Radio, the distance the radio waves travel is heavily dependant on atmospherics.

I regularly have AIS hits over 100nm.
__________________
bewitched is offline   Reply With Quote
Old 02-02-2010, 18:47   #6
Registered User
 
SvenG's Avatar

Join Date: Oct 2009
Location: Mexico heading South
Boat: Ericson 39B - Senta II
Posts: 1,169
Thanks for the answers.

We are about to install the AIS which we just got programmed. It is interesting to know that it is actually possible to get hits from that far away when everything is right.


-Sven
__________________
Senta II - http://www.Grenander.com/Senta_II/Blog/Blog.html
1977 Ericson 39B -- Hull # 216
SvenG is offline   Reply With Quote
Old 02-02-2010, 21:14   #7
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,864
Images: 4
From my home AIS receiver, elevation 1000 ft and a few miles from the ocean, I regularly receive AIS signals 1000 NM away, and occasionally as far as 2000 NM. These are solid signals, too, while they last. This is due to "tropospheric ducting", where the discontinuities in the atmospheric layers act as waveguides.

From the boat, with the antenna about 40 ft (the upper spreader) 100 NM is the maximum range seen so far.
__________________

__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Reply

Tags
ais

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Range BeBalu Monohull Sailboats 6 03-04-2009 10:02
wi-fi range extender bobalpep Marine Electronics 2 09-03-2009 06:35
Navigating a range Aquah0lic Navigation 7 18-01-2009 11:53
Range under power witzgall Monohull Sailboats 21 18-09-2008 07:26
VHF RADIO RANGE GordMay Marine Electronics 16 24-02-2007 10:33



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:57.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.