Wednesday, May 31, 2017

Reply to Duchess on AIS A vs B

I had a question from Dutchess on which is better AIS A or B? I'm  going to reply in a post instead of directly to Dutchess since the subject may be of interest to others.

If you want to participate in AIS (Automatic Identification System) you have several choices:
You can chose to just receive AIS signals from other boats and not transmit your own position. This is the least expensive option. You will need an AIS receiver such as  AMEC CYPHO-150S for $259. It has an internal signal splitter so you can connect it to your VHF antenna on top of your mast for maximum range.

If you you want to transmit your position so others with an AIS receiver can see you (such as very big ships) then you will need either a Class A or Class B transceiver. Class A is for the big boats, it transmits more often and with greater power but it costs more, around $1700. The AMEC CAMINO-701 is such a unit. Be aware that the $1700 cost is only the tip of the iceberg. You would need a heading sensor, GPS antenna, a VHF antenna, a junction box for interfacing with on board equipment, it costs more than the $1700. Only big ships have them installed.

If you want a simpler solution to transmit an AIS position and also receive AIS info from other boats you can chose the CAMINO-108S Class B transponder for $649 (check the box with the integrated splitter). It comes with an internal GPS receiver but requires an external GPS antenna which you can get for $49, the GA-22. Just connect the external GPS antenna, split the power to your VHF radio and route the VHF antenna wire from the mast to the unit. No separate antenna splitter is required. Note, the antenna splitter is an active splitter. It does not introduce signal loss like a dumb splitter. It switches between the AIS transponder and VHF radio in real time with the VHF radio taking precedence if there's a conflict.

On my boat I installed a Class B transponder and routed the output to my Garmin 492 chartplotter but any modern chartplotter will accept AIS input and display the targets on your chart as you move along in real time. The image to the right is AIS data from my Class B transponder as shown on my Garmin 492 chartplotter as I moved through New York Harbor. Note the intersecting red and black lines (black line for me in 10 minutes, red line for someone else in 10 minutes, we are headed to meet, he later changed course).


Steadfast Sailing Travels said...

I have a detailed question to ask and I was not sure of the best place to leave it. If you'd like me to leave it in one of these comments I will or I can send it to an email address. We made it back to Camden Maine from Bradenton Florida on May 25. Though we passed you in the fall and again this spring we have not yet had a chance to say hello and also thank you as your book is a great help as are the blog updates. We're looking forward to buying the latest and our third cruising guide. Enjoy the summer. Jim, SV steadfast

Bob423 said...

Jim, you can ask the question either way, via a comment or email me at If the question may be of interest to others, I may respond with a blog post like I did for Duchess.

By all means, drop by the boat whenever we're in your neighborhood. We've had visitors drop in at every marina we stayed at and at several anchorages. It's always fun to meet cruisers along the way.

Cheap Cruise Tips said...

Great Article and Images.