AIS- A Love Story

[Ozwizz54]

Thanks for posting this, TJ D. Just a few days ago I told my son that the first piece of new equipment to be installed after finding a new boat was AIS. Your post has provided vindication for that belief.

Just wish I could get to a yacht before other people do. I've missed three in the last few weeks. (sigh) My time will come...

David

[TJ D]

Originally Posted by Ozwizz54

Thanks for posting this, TJ D. Just a few days ago I told my son that the first piece of new equipment to be installed after finding a new boat was AIS. Your post has provided vindication for that belief.

Just wish I could get to a yacht before other people do. I've missed three in the last few weeks. (sigh) My time will come...

David

Hi David, you're welcome. As you can see from those of us using AIS, there sure aren't too many detractors!

Good luck on the boat shopping. That's an exciting time. Fear not, there are plenty to go around! You could always pick one up on the W coast USA or Mexico and sail it home... That was a good hobby for some back when the AUD was stronger, but probably still not too bad of a deal if one has the time.

TJ

[sailjumanji]

We recently upgraded electronics with a B&G Zeus2 plotter, Vesper XB8000 AIS, and a new Icom VHF with DSC. This weekend we finally got a chance to really use it on a 200 nm trip motor-sailing mostly on the ICW, plus a few bay crossings that we got to sail. The trip was from Port Aransas to Kemah, Texas. This is a very busy barge area. We have made the trip several times, and you are constantly watching the chart statute mile marks, and lookout for oncoming tows. When you see one, call them "Westbound tow at mile marker x, this is eastbound sailing catamaran Jumanji." Then a short conversation to establish crossing on the one, the two, or request to hold up at a corner, etc.

With AIS, you can identify the oncoming tow by name and call them. Or sometimes they call you. You can see the speed they are traveling - which matters to us because under motors only we are around 5.5 knots, and some travel about that, and some travel much faster (which means you can get caught). We've also had others call us specifically by name to ask about locks we just passed thru, and we hailed some oncoming regarding conditions further up. Anyway, it is great seeing the AIS boats on the plotter, and being able to identify and call by name. We've not gotten to the point of DSC calling, as hailing on VHF has been very easy. Wish I would have installed this years ago!

[Jim Cate]

Wish I would have installed this years ago!

Ahh, but if you had, you wouldn't appreciate it so much now!

Jim

[PuttingDoctor]

Originally Posted by Ozwizz54

Thanks for posting this, TJ D. Just a few days ago I told my son that the first piece of new equipment to be installed after finding a new boat was AIS. Your post has provided vindication for that belief.

Just wish I could get to a yacht before other people do. I've missed three in the last few weeks. (sigh) My time will come...

David

TJ, I want to echo what David said in thanks. AIS is a must and is part of the refit I will undertake come August.

Your post is perfectly timed as the FAA has mandated ADS-B (think AIS for aircraft) for all aircraft operating in the Mode C veil (this is a large portion of airspace in the USA). Mode C is altitude reporting coupled with digital code adjustable transponders.

There are many smaller aircraft owners who are not happy with the 2020 deadline nor the present cost of equipment and installation. My type club for Cessna 150/152 is full of mixed comments re the coming deadline.

I have equipped already with an ADS-B in solution which gives me traffic, live weather and GPS moving map navigation. I will sell the aircraft at year end so will let the next owner equip as desired for the mandated out signal by 2020.

I took your post as being so positive that I in fact posted it in our current discussion of "cost of NextGen avionics" so thanks indeed.

Cheers,

Glen

[jt_kilroy]

Hi, newbie dreamer here, and while I don't have a boat (yet) I do know a whole lot about AIS. Been writing AIS software for seven or so years. IMHO AIS is the single best piece of technology a vessel owner can add to avoid collision. And that is even more so the case for those of you lucky enough to undertake ocean crossings. That container ship cruising along at 18 knots will pick you up a lot earlier with AIS than radar in many cases, IF you are packing a class B transceiver and not just a receiver. Has anyone that is not commercially required sprung for a class A 12.5W device vs. the class B 2W?

I would be very interested to hear from users about the ranges at which they are able to see vessels vs. their antenna heights. On inland waterways, where most of my work is centered. With antenna heights coming close to 70 ft off the water I have seen as far as 80 miles.

[Exile]

Originally Posted by jt_kilroy

Hi, newbie dreamer here, and while I don't have a boat (yet) I do know a whole lot about AIS. Been writing AIS software for seven or so years. IMHO AIS is the single best piece of technology a vessel owner can add to avoid collision. And that is even more so the case for those of you lucky enough to undertake ocean crossings. That container ship cruising along at 18 knots will pick you up a lot earlier with AIS than radar in many cases, IF you are packing a class B transceiver and not just a receiver. Has anyone that is not commercially required sprung for a class A 12.5W device vs. the class B 2W?

I would be very interested to hear from users about the ranges at which they are able to see vessels vs. their antenna heights. On inland waterways, where most of my work is centered. With antenna heights coming close to 70 ft off the water I have seen as far as 80 miles.

From a love story to the realities of the day-to-day relationship:

First, I didn't know recreational vessels were permitted to carry Class A. Is this incorrect? If so, is it more a matter of the much higher price?

Second, any thoughts on using a splitter for a transponder as opposed to installing a dedicated antenna? Thus far I have only installed an AIS receiver on my boat with a splitter/masthead antenna. The performance has been excellent for both AIS & Vhf radio, akin to what was just posted.

[wrwakefield]

Originally Posted by jt_kilroy

Hi, newbie dreamer here, and while I don't have a boat (yet) I do know a whole lot about AIS. Been writing AIS software for seven or so years. IMHO AIS is the single best piece of technology a vessel owner can add to avoid collision. And that is even more so the case for those of you lucky enough to undertake ocean crossings. That container ship cruising along at 18 knots will pick you up a lot earlier with AIS than radar in many cases, IF you are packing a class B transceiver and not just a receiver. Has anyone that is not commercially required sprung for a class A 12.5W device vs. the class B 2W?

I would be very interested to hear from users about the ranges at which they are able to see vessels vs. their antenna heights. On inland waterways, where most of my work is centered. With antenna heights coming close to 70 ft off the water I have seen as far as 80 miles.

Hi JT,

Our AIS antenna [VHF antenna with manual splitter to back-up VHF radio] is atop the main mast (60ft) on our ketch. Along the Inside Passage of Canada and Alaska we commonly see Class A AIS from 30+ miles (remember it is pretty mountainous in most areas...) with our [2 watt] Class B AIS. [Verper Watchman 850] We have been DSC hailed by vessels that are 5-10 miles distant indicating they are receiving our signal from at least that distance.

We are watching with interest the impending release of the 5 Watt SOTDMA Class B AIS transceiver as recently discussed by Ben Ellison on Panbo. I expect that will boost the distance to our AIS transmissions...

For those who asked about AIS/VHF antenna splitters: We are replacing the back-up VHF with a new unit that will become primary, so we will be changing the manual splitter (mentioned above) with an automatic one from Vesper.

Cheers!

[TJ D]

I know, the infatuation just never lasts. Pretty soon, you're finding dirty laundry behind the couch, the toilet seat's up all the time and reality sets in...

I have experience with both class A and B, and while I do not believe that it's illegal for a recreational boat to fit a class A (believe, not 100% sure), I really don't see an upside to doing so. The lower power certainly has enough range for collision avoidance purposes. I don't see the cost of the 'A' units as really justifiable for us running around on pleasure boats. There's really not a big enough difference.

Depending on atmospheric conditions, I can pick up class A vessels at about 30 miles, but I have seen them as much as 500 miles away! (tropospheric ducting is what causes that for those interested)

I can see smaller class B boats from anywhere from 10 to 20 miles. Certainly, even with the lower power, that's plenty of distance for anybody.


As to antenna height, on the current boat, (we have a carbon stick on the new one without a mount) we are only about 8 feet above the water with the antenna. Ranges vary, but 15 miles is about average for detection of either kind of system. I have also had an antenna on the masthead on my previous boat, and 20-30 was average.

I see no reason not to use a splitter. I've gone both ways, and I see no difference in performance.

TJ

[Exile]

Thanks for the helpful comments re: Class A vs. B AIS, as well as those concerning use of antenna splitters. Theree does seem to be a practical limit on how much range a slow-moving recreational vessel really needs to avoid collisions. I suppose the only upside to getting a Class A might be to avoid being filtered out by the big boys upon approaching busy channels & harbors, etc. But my personal take on that is so long as I can "see" & thus avoid them, then all is good!

[Don C L]

Originally Posted by Exile

From a love story to the realities of the day-to-day relationship:

First, I didn't know recreational vessels were permitted to carry Class A. Is this incorrect? If so, is it more a matter of the much higher price?

Second, any thoughts on using a splitter for a transponder as opposed to installing a dedicated antenna? Thus far I have only installed an AIS receiver on my boat with a splitter/masthead antenna. The performance has been excellent for both AIS & Vhf radio, akin to what was just posted.

I too have been wondering about the pros and cons of splitter vs. second antenna. In my case it looks like the antenna, and installation, is cheaper than the splitter. It is clear that AIS is a game-changer, as they say. Where I am, where fog can roll in while you are crossing a shipping lane, and an AIS blip will not be mistaken for anything else... I am saving up for the full enchilada. But even now I can see others on my cell phone as long as I am in range of a tower. Pretty amazing stuff for old guys who grew up with ded. reckoning, Loran, RDF etc.

[TJ D]

By the way, we are using the Vesper automatic splitter. I think it cost about $200, so one could run another antenna if desired for less, but I just didn't feel like it!

I don't think that manual ones are a good idea if one's going to use a single antenna, since you would only have functionality on one thing or the other, and we do like to keep a listening watch on the VHF all the time.

TJ

[jt_kilroy]

I have not used the Vesper splitter but I have used the SiTex device, very similar. I can't say that I have seen any increase in range from these various active devices but I also don't feel like I have lost range either. A dedicated antenna is not really worth it unless you have an antenna that is actually tuned to roughly 162 MHz and even then I doubt it will result in much better results.

I have done some testing with various Yagi directional configurations and noticed very significant range increases, on the order of 50%. A three element Yagi does give a pretty wide angle and can really increase your forward visibility but not really useful on a boat.

[Cadence]

Originally Posted by jt_kilroy

I have not used the Vesper splitter but I have used the SiTex device, very similar. I can't say that I have seen any increase in range from these various active devices but I also don't feel like I have lost range either. A dedicated antenna is not really worth it unless you have an antenna that is actually tuned to roughly 162 MHz and even then I doubt it will result in much better results.

I have done some testing with various Yagi directional configurations and noticed very significant range increases, on the order of 50%. A three element Yagi does give a pretty wide angle and can really increase your forward visibility but not really useful on a boat.

Am reading this correctly? Is the Yagi not seeing what may be coming up behind you?

[colemj]

A splitter will not amplify a signal, and a good one should have no insertion losses. A yagi or other directional antenna is not practical.

Mark