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Old 27-01-2015, 12:54   #31
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Re: class A AIS

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Originally Posted by RDW View Post
Now the real question was can I just plug in a new class a transponder where my old class b was. I think I know from a little reading that the class a has more features,
Assuming your existing AIS Class B transponder is outputting NMEA 0183 at 38.4k, and whatever Class A transponder you choose also does the same, then you are good-to-go!!

(If you were to require NMEA 2000 interface, you'll need to look for a Class A transponder that does NMEA 2000, or use a multiplexer...)





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Originally Posted by RDW View Post
own GPS, own antenna and therefore I can not do a real simple exchange one unit for the other.
You have us a bit confused here....as all AIS transponders (whether Class A or Class B), have their own GPS receivers built-in, and require their own GPS antenna....
(although there are some that have provision for NMEA data input, let's not go down that rabbit hole...



So for the fun of it lets assume that indeed I have to have a class A transponder, has anyone experience doing the install yourself. I have a Raymarine E 80 chart plotter, raymarine radar and sea talk and also have a lap top connected to the whole mess.
RDW
You should just take the new Class A AIS NMEA 0183 data (at the high rate of 38.4k) and input that to you E-80 plotter...
You should already have the E-80 configured to accept NMEA 0183 at the 38.4 rate, on one of its inputs....but if not, it's an easy menu item to change...

I hope this helps...

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Old 27-01-2015, 13:38   #32
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Re: class A AIS

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Originally Posted by RDW View Post
Now the real question was can I just plug in a new class a transponder where my old class b was.
RDW
You do not have, nor have you ever had a "Class B".

You have a RECEIVER.

It receives both Class B and Class A



Understand it now?
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Old 27-01-2015, 16:45   #33
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class A AIS

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Originally Posted by RDW View Post
I currently have a Class B receiver AIS connected to a Raymarine E 80 chart plotter. The chart plotter is intergrated with my radar, gps and navonics charts.
I need to upgrade to class A AIS. Required for World Arc.
Can I just buy a unit and plug it into where the other one was ?
Sorry if I am not giving you enough information.
I am just beginning to look into this!
RDW

Hi OP, not sure if this has been said , there is no such thing as a class B receiver.

Doh, just saw MarkJ,s post
Dave


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Old 27-01-2015, 16:54   #34
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Re: class A AIS

So you doubting Thomas's are right. Glad I did not try to place a bet with any of you.
KA4WJA, thanks for the additional info. Just to refresh your memory. You have helped me over my SSB on SSB problems.


Hi Bob,

Thank you for your email and thank you for pointing this out. It would seem that the information in the pack attached to the previous email was not correct.

For World ARC a Class A or B AIS transponder is required. So for clarification a Class B Transponder would be acceptable. Please see page 7 of the attached conditions of entry.

Let me know if you have any other question

Best regards
Sally

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Cowes PO31 7AX
United Kingdom
E. mail@worldcruising.com
T. +44 (0)1983 296060
F. +44 (0)1983 295959
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Old 27-01-2015, 17:08   #35
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Re: class A AIS

Good work emailing them.
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Old 04-02-2015, 22:15   #36
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Re: class A AIS

Class A
Vessel-mounted AIS transceiver (transmit and receive) which operates using SOTDMA. Targeted at large commercial vessels, SOTDMA requires a transceiver to maintain a constantly updated slot map in its memory such that it has prior knowledge of slots which are available for it to transmit. SOTDMA transceivers will then pre-announce their transmission, effectively reserving their transmit slot. SOTDMA transmissions are therefore prioritised within the AIS system. This is achieved through 2 receivers in continuous operation. Class A's must have an integrated display, transmit at 12.5 W, interface capability with multiple ship systems, and offer a sophisticated selection of features and functions. Default transmit rate is every few seconds. AIS Class A type compliant devices receive all types of AIS messages.
Class B
Vessel-mounted AIS transceiver (transmit and receive) which operates using either carrier-sense time-division multiple-access (CSTDMA)or SOTDMA; there are now 2 separate IMO specifications for
Class B. Aimed at lighter commercial and leisure markets. CSTDMA transceivers listen to the slot map immediately prior to transmitting and seek a slot where the 'noise' in the slot is the same or similar to background noise, thereby indicating that the slot is not being used by another AIS device. Class Bs transmit at 2 W and are not required to have an integrated display: Class Bs can be connected to most display systems where the received messages will be displayed in lists or overlaid on charts. Default transmit rate is normally every 30 seconds, but this can be varied according to vessel speed or instructions from base stations. The Class B type standard requires integrated GPS and certain LED indicators. Class B equipment receives all types of AIS messages.
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Old 04-02-2015, 23:28   #37
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Re: class A AIS

OK... I understand the power differences between A&B but that aside, why would you spend an extra $2k-3k for a Class A without a legal requirement? The range on a B seems to be plenty to provide sufficient situational awareness, and the transmission priority seems to be less important for non-commercial sailors...

Can anyone offer an opinion?
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Old 04-02-2015, 23:33   #38
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Re: class A AIS

The International Maritime Organization's International Convention for the Safety of Life at Sea requires AIS to be fitted aboard international voyaging ships with gross tonnage (GT) of 300 or more, and all passenger ships regardless of size
But the differences are ...
http://www.navcen.uscg.gov/pdf/AIS_C...n_By_Class.pdf
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Old 04-02-2015, 23:47   #39
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Re: class A AIS

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Ok, but still I don't see a difference in functionality worth the additional price...

I'm happy with it just being an opinion thing, but am wondering if I am missing something which makes the class A desirable to a recreational sailboat in the 30-60' size range.
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Old 05-02-2015, 00:18   #40
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Re: class A AIS

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Ok, but still I don't see a difference in functionality worth the additional price...

I'm happy with it just being an opinion thing, but am wondering if I am missing something which makes the class A desirable to a recreational sailboat in the 30-60' size range.
You're not missing anything.

If everyone had class A the airwaves would be a lot more crowded in busy harbors and other heavy traffic areas. Also, small craft can't take much advantage of the higher power anyway because their antenna height is less than large craft.
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Old 05-02-2015, 03:35   #41
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Re: class A AIS

For a cruising yacht a Class B transponder is all you need
You can see them, they can see you...all the additional data that Class A provides is hardly relevant to a "relatively" maneuvrable sailing yacht.
i wonder how many of the respondents have actually sailed across oceans with or without AIS and what their real world experience has been.
We have a Class B transponder and all shipping we have seen have seen us also, confirmed with VHF contact, and avoided collision by appropriate action.
The A vs B debate is hardly relevant for small cruising yachts IMHO.
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Old 28-02-2015, 18:52   #42
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Re: class A AIS

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If everyone had class A the airwaves would be a lot more crowded in busy harbors and other heavy traffic areas. ...
I confirmed this with vessel traffic controllers while visiting the USCG facility at Yerba Buena Island, San Francisco, today. The Coast Guard normally only tracks class A AIS. They do, however, have multiple sophisticated radars and powerful cameras strategically located to observe marine traffic. Ships may or may not be monitoring class B transmitters.
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Old 08-03-2015, 04:45   #43
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Re: class A AIS

You can buy a B-class transponder with 12.5w RF power output like A-class from Turkey around 1000 euros.
We have special regulations for B-class transponders here..
Voyage data records, SAR buttons, 12.5w power are standart in Turkey.
You could find 3 local brands (IDC, Serenity and i-Marine) at market with that extra features.

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Old 08-03-2015, 06:00   #44
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Re: class A AIS

Quote:
Originally Posted by Andy73 View Post
Ok, but still I don't see a difference in functionality worth the additional price...

I'm happy with it just being an opinion thing, but am wondering if I am missing something which makes the class A desirable to a recreational sailboat in the 30-60' size range.
Anyone thinking about Class "A" should consider the fact that the differences in function are not all positive.

Class "A" sets require you to program voyage data every time you go out. Destination, ETA, etc. Plus, you are supposed to keep your nav status up to date. That means that every time you go from being under sail to motoring or motor-sailing, you're supposed to change nav status. You could just fail to do it, but how bogus would it be to be broadcasting false data over Class "A"?

In theory, it would be great to have both -- Class "A" for long passages, and Class "B" for normal sailing around. In practice, who would bother? Seems OTT to me. I'm really interested to hear about the 12.5watt Turkish sets. I'm going to look at those now. Might be the perfect compromise for us.
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Old 08-03-2015, 08:12   #45
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Re: class A AIS

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Originally Posted by ozicozy View Post
You can buy a B-class transponder with 12.5w RF power output like A-class from Turkey around 1000 euros.
We have special regulations for B-class transponders here..
Voyage data records, SAR buttons, 12.5w power are standart in Turkey.
You could find 3 local brands (IDC, Serenity and i-Marine) at market with that extra features.

(Tapatalk)

If this is true I foresee lots of technical problems. I wonder if IMO is aware and supports Turkey in this?
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