Cruisers Forum
 


Join CruisersForum Today

View Poll Results: Want to have an AIS transponder or only see others how have?
Yes 53 86.89%
No 8 13.11%
Voters: 61. You may not vote on this poll

Reply
 
Thread Tools Rate Thread Display Modes
Old 31-10-2011, 12:30   #91
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Re: AIS Transponder: Yes or No

So, does Class A broadcast at greater than 25 watts? I don't think that how often info is broadcasted would have anything to do with the antenna design, would it?
__________________

__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 31-10-2011, 12:39   #92
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 1,793
Send a message via Skype™ to Auspicious
Re: AIS Transponder: Yes or No

Quote:
Originally Posted by David M View Post
Did Larry or Shawn give a reason for a FA150 (Class A AIS transceiver) requiring a special AIS antenna? Power does not seem to be the reason because VHF antennas are connected to transmitters that are limited to 25 watts....unless Class A is greater than 25 watts? Could that be the reason?
I'd like to give Furuno more than a few minutes to review the write-up I did of our discussion.

Quote:
Originally Posted by David M View Post
So, does Class A broadcast at greater than 25 watts? I don't think that how often info is broadcasted would have anything to do with the antenna design, would it?
Class B AIS transponders run at 2 watts. I don't recall the power level of Class A but it is lots more (10? 25?).
__________________

__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 31-10-2011, 12:43   #93
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Re: AIS Transponder: Yes or No

Oh interesting...I bet that's its...power transmission makes the difference in antenna design?
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 31-10-2011, 13:15   #94
Sponsoring Vendor

Community Sponsor

Join Date: Dec 2010
Location: Auckland, New Zealand
Boat: Nordic 40
Posts: 209
Re: AIS Transponder: Yes or No

Class A is 12.5 watts maximum
__________________
Jeff Robbins, Nordic 40 "Vesper", New Zealand
www.vespermarine.com
jeffrobbins is offline   Reply With Quote
Old 31-10-2011, 13:23   #95
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,674
Re: AIS Transponder: Yes or No

Class A transmit power=12W. Normal VHF antennas should work just fine: AIS-tuned might work a little better. If there is a problem getting out there are a number of possible causes. My brand-new (expensive) VHF had a 5:1 SWR out of the box, so don't assume that premium brands don't have quality issues.

Check Wikipedia: Automatic Identification System - Wikipedia, the free encyclopedia

I stand corrected: Class A and B have different position messages. Still, all Class A systems will recognize Class B positions, if not static data.
__________________
CarinaPDX is online now   Reply With Quote
Old 31-10-2011, 13:27   #96
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,674
Re: AIS Transponder: Yes or No

Was I really working on the last post for 8 minutes, while jeffrobbins got the answer in?

I must be slowing down...
__________________
CarinaPDX is online now   Reply With Quote
Old 31-10-2011, 13:28   #97
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 1,793
Send a message via Skype™ to Auspicious
Re: AIS Transponder: Yes or No

Quote:
Originally Posted by CarinaPDX View Post
Class A transmit power=12W.
Thanks Jeff. I looked and couldn't find the number, and couldn't remember for sure.

For the rest of your statement I'm feeling a little constrained by my offer to Furuno to review the summary of our phone call.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 31-10-2011, 15:04   #98
Registered User
 
S/V Alchemy's Avatar

Join Date: May 2008
Location: Toronto
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,576
Re: AIS Transponder: Yes or No

I like threads where I see information in greater detail like this one. Good stuff, guys.
__________________
S/V Alchemy is offline   Reply With Quote
Old 02-11-2011, 07:53   #99
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: AIS Transponder: Yes or No

What I would like to remark is that any VHF antenna that shows VSWR 4:1 at AIS (which is on regular VHF channels/frequencies) should be banned from selling as a marine VHF antenna.

I think I remember that a marine VHF antenna should have a max. VSWR of 2:1 over the complete VHF bandwidth, which should make them all at least suitable for AIS work. A 1.1:1 AIS antenna is of course much better than a 2:1 one (which looses half the power/3dB).

I have noticed big differences between VHF antenna designs too. I switched my main VHF antenna to a di-pole design (instead of standard ground plain design) and get much better range. For most people reading this: renewing your coax cable will probably make a bigger difference than buying a better antenna.

On my mizzen I have a simple VHF stainless whip (Shakespear ground plane) and it works well enough on my class-A AIS.

Last but not least: every coax/antenna installation should be checked with meter and dummy load (connect dummy load at antenna position too). I have seen too many installations where there was either a 100% short or even 100% open connection (asking me: are those connectors supposed to be soldered??!! ouch...)

ciao!
Nick.
__________________
s/v Jedi is offline   Reply With Quote
Old 02-11-2011, 07:56   #100
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Re: AIS Transponder: Yes or No

I found the solderless coax connectors to be junk. I went back to the old fashioned yet more reliable way...soldering.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 02-11-2011, 08:29   #101
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: AIS Transponder: Yes or No

Quote:
Originally Posted by David M View Post
I found the solderless coax connectors to be junk. I went back to the old fashioned yet more reliable way...soldering.
Yes but the problem was that this cruiser used a solder-connector without soldering it... many don't even know that there are two kinds so the solderless connectors get bad rep when stories about connectors that have not been soldered come up... even though those stories are about connectors that are supposed to be soldered.

:-)

cheers,
Nick.
__________________
s/v Jedi is offline   Reply With Quote
Old 02-11-2011, 10:49   #102
Registered User

Join Date: Feb 2008
Posts: 2,061
Re: AIS Transponder: Yes or No

My boatyard used a solderless connector on my masthead -- Inspected it and found the pins hadn't even pierced the insulation fully. I cut it off and soldered on a new one. Now I know its good for the life of the cable.
__________________
SailFastTri is offline   Reply With Quote
Old 02-11-2011, 11:50   #103
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: AIS Transponder: Yes or No

Quote:
Originally Posted by SailFastTri View Post
My boatyard used a solderless connector on my masthead -- Inspected it and found the pins hadn't even pierced the insulation fully. I cut it off and soldered on a new one. Now I know its good for the life of the cable.
Exactly. The thing is that with some practice, it is not too difficult to make good connections with those solderless connectors. Also, without much practice, it's not too difficult to ruin a solder connector by using too much heat which melts the insulation around the inner conductor and creates a full short between the two conductors of the cable.

So it all comes to experience putting these connectors onto cables. And once you get enough experience, you will prefer soldering types unless it's outside in the wind where it's very difficult to make a proper solder connection, in which case you know how to make a proper solderless connection. I hope anybody reading this can follow me :-8

ciao!
Nick.
__________________
s/v Jedi is offline   Reply With Quote
Old 02-11-2011, 12:02   #104
Sponsoring Vendor

Community Sponsor

Join Date: Dec 2010
Location: Auckland, New Zealand
Boat: Nordic 40
Posts: 209
Re: AIS Transponder: Yes or No

Yes, I agree. At the risk of repeating myself.... my experience providing technical support to people installing transponders has taught me that the vast majority of problems are due to antenna connectors. People are quick to jump to the conclusion their transponder isn't working but in the end it often comes to a connector somewhere. Don't overlook old and tired cable too.
__________________
Jeff Robbins, Nordic 40 "Vesper", New Zealand
www.vespermarine.com
jeffrobbins is offline   Reply With Quote
Old 02-11-2011, 12:13   #105
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,198
Re: AIS Transponder: Yes or No

Quote:
Originally Posted by jeffrobbins View Post
the vast majority of problems are due to antenna connectors. People are quick to jump to the conclusion their transponder isn't working but in the end it often comes to a connector somewhere. Don't overlook old and tired cable too.
I'll take it a step further: it's my experience that at least 50% of the cruisers out here have some sort of problem with coax cables, connectors or antennas. Flip a coin to get the feel for 50%, then make sure you're not in the wrong 50% :-)

ciao!
Nick.
__________________

__________________
s/v Jedi 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
Problem with AIS taku OpenCPN 4 03-10-2014 10:17
Collision Avoidance in Mexico: AIS or Radar or ? no_bad_days Pacific & South China Sea 27 19-09-2011 16:40
Route Properties, Missing Functions James Baines OpenCPN 13 13-07-2011 05:31
AIS Plus Other Goodies Windjammr Spirt Marine Electronics 0 10-07-2011 16:26
AIS Reception Issue twistedtree Marine Electronics 72 03-07-2011 04:57



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:15.


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.