AIS How do you use it? Vs Small vessles

Hi,

This could sound like the most basic question to fall out of the sky in a while…

I am a cruising sailor with a circumnavigation under the belt on this cruise. I sail solo because all women hate me :wink:

Theres some specific questions about how ships use AIS that cruising sailors argue about…

  • What is a ships prime avoidance system: Radar or AIS? Yes I know you have both, but what is used mostly in a practical sense?
  • At 2.33am is the watch keeper allowed to alter course of a ship with an AIS target or does he need to wake the captain? How long does that take? More generally how long does a ship take from target acquisition to change of course?
  • It appears to me (and overhearing VHF conversations) that many shipping lines have a set minimum CPA. Is that correct? Is 1nm normal?
  • Do ships filter out Class B signals at all? Or in harbours? etc.
  • I appear to have some ships start to divert at 10nms. Is that likely or some aberration?
  • Do ships ‘click’ on a target to determine if the target is a sailing vessel, or is it assumed all vessels are motor vessels?
  • My boat normally is doing about 6 knots (erratically). In practice, does a ship doing, say, 15 knots divert or stand on if they are the Stand On vessel.
  • What range do ships normally first get an AIS contact and does a Class B contact first appearing so much closer give surprise/irritation?
    [FONT=Helvetica][SIZE=2]* What range would a ship see a sailing boat thats not equipped with AIS? Or would you see us at all!

Any other advice for sail boats, small vessels?

Thanks for your help :slight_smile:

Mark[/SIZE][/FONT]

How about this, get out of the way regardless of what the rules say.

In the end only this rule should apply. He who has the most tonnage make the rules.

Most of us are oil filed guys in the GOM, so for us we set up on a course that will let us cut through the most fields with as few course changes as possible. Nothing pisses me off more then somebody who is piddling about makes me change course and now I have to figure out a whole new route because even a 5 degree course change causes everything I had planned to fall apart. I’m sure ships working around the Islands have the same considerations due to their draft and feel the same way.

I am more asking about being at sea.

I work in the GOM and also live on a Boat in my off time. I can try to answer some of your questions.
As for AIS or Radar? Most of the time the AIS signal is transferred electronically right to the Radar screen, so we use both. Remember that AIS goes through a VHF radio signal so on the open sea radar has a longer range to pick you up. Also most Radars on big ship have ARPA that are good at picking up course changes. As for the watch stander being able to change course at any time, yes that is their job, do not have a collision.
The CPA requirements are determined by the masters standing orders, usually 2 miles on the open seas. As a solo sailor on the open sea I fail to understand how you can keep a constant lookout, you have to sleep some time. The law requires a constant look out, Sail boats are NOT exempt. When it comes to the pecking order under the international rules of the road, sailing vessels are #5 on the list.
So if you are considering getting an AIS on your boat? Yes it will help tremendously in helping a ship avoid you.

Just having your vessels name via the AIS is a big help because I can hail you by name…this assumes a radio watch is maintained…

Specifically the VHF radio, not the other one

Remember, when hailing a foreign ship you have to allow for the time of the initial call until the time they can go find the guy that speaks English.

1 You hail the vessel
2 The vessel responds with just their name.
3. You send your message and there is no reply
4 You hail the vessel again and there is no reply
5. You hail the vessel again and after a long delay a different voice comes on and answers.

[QUOTE=psquiggs;113212]
Most of the time the AIS signal is transferred electronically right to the Radar screen, so we use both. Remember that AIS goes through a VHF radio signal so on the open sea radar has a longer range to pick you up. [/QUOTE]

Doesnt the AIS go onto your chart plotter? Does the radar screen overlay a chart?

I didnt know radar has a greater range at sea. Only on ships as sail boats radar is quite low, whereas the VHF antenna is normally top of the mast, aprox 60 feet above water.

As a solo sailor on the open sea I fail to understand how you can keep a constant lookout, you have to sleep some time.

So if you are considering getting an AIS on your boat? Yes it will help tremendously in helping a ship avoid you.

Well the solo sailor / constant lookout is the conundrum that wont be easily resolved because there will always be old men running away to sea. I agree with you its not optimal. Sleep is not difficult for me, personally, but few can do 20 minute naps over a long passage effectively, safely or enjoyably.
My first solo voyage, without AIS, was Nice in France, Palma, via Gib, to canary Islands then to the Caribbean.
With AIS I have done Caribbean to New York, ICW, Key West through New Providence Channel to Caribbean.
For me, AIS is the most important safety innovation since GPS. If gives me the chance to be spotted. A fibreglass 40 foot yacht has little radar reflection. Our lights are 2NM range only!!
However there is strong resistance by sailing boats, especially from teh USA, to AIS. Many are afraid the US government will track them; many think no fishing boats have them so nor should they; expense… they are $500 for a cheap Class B transponder, $800 for a good one.


This screenshot in the Florida Straits shows 3 ships diverting. Range ring is 10nms. No VHF comms necessary in this instance.
For a solo sailor this is the only way I can really tell if someone has seen me.

By being better informed about how you use it, and navigate in general, small boats may be able to increase their overall safety. :slight_smile:

Thanks for the advice and thoughts.

[QUOTE=MarkJ;113158]Hi,

This could sound like the most basic question to fall out of the sky in a while…

I am a cruising sailor with a circumnavigation under the belt on this cruise. I sail solo because all women hate me :wink:

Theres some specific questions about how ships use AIS that cruising sailors argue about…

  • What is a ships prime avoidance system: Radar or AIS? Yes I know you have both, but what is used mostly in a practical sense?
  • At 2.33am is the watch keeper allowed to alter course of a ship with an AIS target or does he need to wake the captain? How long does that take? More generally how long does a ship take from target acquisition to change of course?
  • It appears to me (and overhearing VHF conversations) that many shipping lines have a set minimum CPA. Is that correct? Is 1nm normal?
  • Do ships filter out Class B signals at all? Or in harbours? etc.
  • I appear to have some ships start to divert at 10nms. Is that likely or some aberration?
  • Do ships ‘click’ on a target to determine if the target is a sailing vessel, or is it assumed all vessels are motor vessels?
  • My boat normally is doing about 6 knots (erratically). In practice, does a ship doing, say, 15 knots divert or stand on if they are the Stand On vessel.
  • What range do ships normally first get an AIS contact and does a Class B contact first appearing so much closer give surprise/irritation?
    [FONT=Helvetica][SIZE=2]* What range would a ship see a sailing boat thats not equipped with AIS? Or would you see us at all!

Any other advice for sail boats, small vessels?

Thanks for your help :slight_smile:

Mark[/SIZE][/FONT][/QUOTE]

AIS is best for detection of small targets particularly during times of less then ideal radar conditions, rain showers or a choppy sea. Avoidance of is done (or is supposed to be done" using ARPA as it is more reliable then AIS for avoidance if conditions allow.

Most watch standers are authorized to change course without calling the captain. There may be some exceptions.

A min 1 mile CPA is very common, a closer CPA triggers a call to the captain.

No filtering that I am aware of.

Course change at 10 miles or so common. Some ships use time as a criteria.

As to clicking, S/V motor vessel, not in most cases likely, ships will just stay clear of whatever it is.

Most ships will change course before risk of collision exists. No all.

AIS targets appear on the 12 mile screen used with offset so 15+ miles or so? Don’t know about less powerful AIS signals.

A S/V without AIS may be difficult to detect in rain showers or a sea. Mates often do not have the radar tuned properly, some commercial radars poor at target detection, side lobes coming off big targets can hide small targets.

Yes in most cases AIS is displayed on Electronic charts. Some radars will overlay on a chart but not very common to commercial navigation that I know of. Remember the best navigation tool is your eyes and not the computer screen.

I love our AIS overlayed chartplotters. More and more smaller yachts and sailboats are installing them and I think thats good. Its helps back up my Mk.1 eyeball and my radars. It also gives you a name to call on the radio. It helps make transiting an area with lots of small craft around a little less stressful.

Sleeping with nobody “watching the cash register” is complete nonsense whether it be a small boat or not; i know “solo” long distance sailors do it but its entirely unacceptable in my book. Regardless of your electronics someone should be looking at the horizon.

Everyone having AIS becomes a nusance in a lot of places cluttering the screeen taking away from what i’m really looking for.

[QUOTE=MarkJ;113158]Hi,

This could sound like the most basic question to fall out of the sky in a while…

I am a cruising sailor with a circumnavigation under the belt on this cruise. I sail solo because all women hate me :wink:

Theres some specific questions about how ships use AIS that cruising sailors argue about…

  • What is a ships prime avoidance system: Radar or AIS? Yes I know you have both, but what is used mostly in a practical sense?
  • At 2.33am is the watch keeper allowed to alter course of a ship with an AIS target or does he need to wake the captain? How long does that take? More generally how long does a ship take from target acquisition to change of course?
  • It appears to me (and overhearing VHF conversations) that many shipping lines have a set minimum CPA. Is that correct? Is 1nm normal?
  • Do ships filter out Class B signals at all? Or in harbours? etc.
  • I appear to have some ships start to divert at 10nms. Is that likely or some aberration?
  • Do ships ‘click’ on a target to determine if the target is a sailing vessel, or is it assumed all vessels are motor vessels?
  • My boat normally is doing about 6 knots (erratically). In practice, does a ship doing, say, 15 knots divert or stand on if they are the Stand On vessel.
  • What range do ships normally first get an AIS contact and does a Class B contact first appearing so much closer give surprise/irritation?
    [FONT=Helvetica][SIZE=2]* What range would a ship see a sailing boat thats not equipped with AIS? Or would you see us at all!

Any other advice for sail boats, small vessels?

Thanks for your help :slight_smile:

Mark[/SIZE][/FONT][/QUOTE]

  1. ARPA is the only approved collision avoidance system we have on board. This is from both a practical and legal sense. AIS is an aid and a good visual indicator on the ECIDS or radar overlays, but is NOT for collision avoidance. It is fine for ballparking a CPA, but should never be relied on. The reason is that the AIS target I see, is generating it’s CPAs based on the target’s own AIS equipment. I’d rather not rely on someone else’s equipment or calibration of that equipment. We have the ability to overlay AIS on the ECDIS and Furuno radars we have, but typically leave it off the radars because it overlays the target echos and doesn’t allow you to easily acquire the return if AIS is on.

  2. As a watch officer, I follow whatever the Master’s Standing Orders are for that captain, but generally they include something along the lines of “…maintain at all times a CPA greater than 1nm”. I am free to maneuver as necessary within the Rules and take prudent and effective action to avoid collision while following the standing orders.

  3. This might depend on the area. For instance though, I know San Francisco VTS enforces a 1nm CPA in the offshore precautionary area.

  4. We can filter based on a number of conditions (the same with ARPA), but the type of AIS class is not one of them. Class B targets tend to be obvious offshore though, they don’t update as often from my experience and don’t appear until closer in.

  5. It all depends on the watch officer and what their standing orders are. The captains I sail with don’t give specific instructions, just the guidelines to stay within. I maneuver according to Rule 8 and within my comfort zone for that particular situation. With a large vessel, that very well may be 10nm depending on how he is behaving in general, whether I could hail him on VHF, how he sounded on the radio (did he really understand the situation?), etc; or sometimes it’s at a time before CPA instead so we’re not deviating too early for a slowly developing situation. With small targets, I tend to wait until we are closer. I’ve found that small vessels might not appreciate a course change so early, and their perception of danger or a collision situation doesn’t occur until closer ranges. At 10nm, they might not even be aware that there is a situation developing with this shadow they may or may not see near the horizon.

  6. Honestly, I will always take action as necessary within the Rules, but if I discern that the echo on the radar or the weak lights I see on the horizon belong to a small vessel, I know I might be in for a stressful situation. From a strictly electronic standpoint, I can discern from the radar return the size of the vessel and even if it is fiberglass. Smallish fishing boats won’t pop up until 8-10nm, but usually will deliever a half-way decent return (typically being metal), fiberglass recreational vessels show up even closer with a weaker return. If your vessel has AIS, then it should be indicating the correct vessel type, and I would look at that too just to get an idea. I will also look at destination info and ETA, sometimes this lets me know how much of a hurry the guy is in. But for example, if I see a weak return suddenly pop up at 6nm going 5knots… bingo, sailing vessel. And of course, I’m looking out the window too and at night I’ll have a dedicated lookout on the bridgewing. I take advantage of other radar features too to help me identify targets.

  7. I for one, follow the navigation rules. There may be some here that play by tonnage, but that is far from an acceptable excuse if something were to happen. But the Rules are mutual, and the commercial sailors on here have all had close calls that muddy our perspective, shoot, even my username is remnant of that!! But I’ve learned that not every sailboat is a W.A.F.I.; that is reserved for a special breed, and over time the ratio of good to bad that I’ve encountered has improved. I am a professional mariner, this is my job, my career, I take pride in playing by the rules and being good at what I do, and I think we all share that here. Your questions here are all about getting to a mutual understanding, and I applaud your interest. All bets are off though if you are obviously not following the Rules; maintaining an effective radio watch is one of them.

That said, if I am offshore and am the stand-on vessel, I will stand on. Preferably, we will discuss each other’s intentions on the radio and clarify our responsibilities. If the other vessel is the give-way, I will always impress that upon them in the first contact so there is no question, and set the tone right away (some might call this “bullying”, I prefer “effective communication”). Certain terms or phrases like “I intend to maintain course and speed”, “I will alter course to starboard and meet you port to port”, etc, etc, should be in your brain when communicating. Foreign vessels where english is the second language know the rules and how they are written – speaking the rules when communicating will make sure everyone is on the same page. It sounds hokey to inland guys who have their own lingo (I’ve been there), but it is the clearest way to avoid miscommunication. All foreign watch officers are required to speak english; how well they do can be a crap shoot. Now, if you are sailing erratically and you are the stand on, I expect you to stand-on. The rules make no allowances for a vessels that feel free to do whatever they want; everyone has responsibilities. Part of my job as a watch officer is to monitor [I]your[/I] actions as well to make sure you are doing what we discussed and what you are required to do within the Rules.

  1. It all depends on the propagation at the time. Remember, AIS is just a VHF signal, generally line of sight, but atmospherics play a role too. I’ve seen targets with display information 300nm out with good atmospherics, but typically, within 30nm for a commercial AIS. Class B doesn’t seem to show up until perhaps 10nm, but that is really just a guess because I can’t tell the type of AIS, just what I’ve gathered.

  2. At night all depends on your lights. The combined lights atop the mast work better in this regard. During the day, good luck depending on the sea conditions. On the radar, it is pretty iffy, but in the 6-8nm range at best, but probably not an acquirable echo. Fiberglass gives a terrible return; combine that with pitching and rolling and going into the trough, ARPA has a tough time latching on. I use target trails as a backup to ballpark it, true or relative depending on the situation, sometimes one on each radar. I work in some pretty nasty conditions, so depending on the sea conditions and how I have to tune my radars to get anything appreciable out of them, there is the possibility that I might not see you at all. Then again, in those conditions, I doubt a sailing vessel would be afloat. Like Kennebec Captain mentioned, there is always the possibility the watch officer has the radar tuned down too far. Clutter controls always have drawbacks, as they typically reduce close-in and weak returns. I use true trails in this situation (“snail trails”), even through clutter and weak echos, it will still draw a straight line behind a target; you see that in the midst of a bunch of clutter, theres a decent chance a vessel is out there. But this is why we maintain an effective lookout.

As far as other advice… Read, understand, and abide by the Rules of the Road if you haven’t done so already. Keep a copy on board like you’re required to and refer to it when necessary. Get a good radar reflector for your mast. Also, I know someone who sails regularly and he uses a radar [I]detector[/I], like for a car. They pick up X-band radar signals; lets you know a ship’s radar is within line-of-sight. Some detectors can indicate the direction it is coming from. A pretty good tool to aid in large-vessel awareness offshore.

And lastly, get a good VHF radio, two perhaps, set one to 13 and one to 16 offshore, and install antennas as high as possible. Nothing is more infuriating when you are hailing a vessel and get no response, then suddenly they want to play the Rules card on you. Nope, sorry. I tried, you failed in your responsibilities, I am now following what I feel to be the best course of action. Something I’ve picked up from pilots is to repeat the phrase “negative contact” over the radio if I fail to get a response. The USCG records 13 and 16 (within range), and if I have to say that phrase, at that point I have given up on resolving the situation mutually and have switched to preparing for potential litigation. Don’t let it get to that point.

Isn’t iron mike always at the helm lol…

[QUOTE=Kennebec Captain;113222] Avoidance of is done (or is supposed to be done" using ARPA as it is more reliable then AIS for avoidance if conditions allow.

[/QUOTE]

Interesting stuff that because most small boats radar doesnt have ARPA, but, [U]at best[/U], M-ARPA:

Mini-automatic radar plotting aid (or MARPA) is a radar feature for target tracking and collision avoidance. Targets must be manually selected, but are then tracked automatically, including range, bearing, target speed, target direction (course), CPA (closest point of approach), and TCPA (time of closest point of approach), safe or dangerous indication, and proximity alarm. MARPA is a more basic form of ARPA (automatic radar plotting aid).
The major difference of this Radar plotting aids may not be fully equivalent to all ARPA performance standard of IMO approved type which is a mandatory requirement for large ocean-going ships. Therefore, they are less expensive for small craft.


But I dont think I have seen a sail boats radar with even MARPA. And too few sail boats use radar at night at all… they may have the machine on Stand-By but the antenna is stopped and its not transmitting. This is because they use a lot of power. Class B AIS, by the way, transmits at 2 watts instead of 25 watts for Class A, effectivly meaning Class B can stay on 24/7 and not consume much at all.

Thanks for the information and discussion :slight_smile:

Mark

Wafinator great post! It may take me a while to let all the points you make fully settle in.

On Point 5 I agree with you that small vessels off shore cant appreciate an early course change without electronics. So a boat without AIS or Radar (most boats) can only determine a close CPA using a hand baring compass on the rolly deck. Its not easy at more than 5nms as the bearing remains the same in any case. By the time many sail boats can get better bearings they think they are getting too close and pull the fear factor of the tonnage ‘rule’ and make a change in course, sometimes for no reason, sometimes putting themselves into actual danger.

Class B AIS only updates every 30 seconds instead of 10 seconds for Class A. So ships must get some wildly erratic headings from sailing boats. My heading can be 30 degrees either side of my course but in rough seas thats as good as an olympic helmsman!

Thanks for your thoughts :slight_smile:

[QUOTE=MarkJ;113236]

… Class B AIS only updates every 30 seconds instead of 10 seconds for Class A. So ships must get some wildly erratic headings from sailing boats. My heading can be 30 degrees either side of my course but in rough seas thats as good as an olympic helmsman!

Thanks for your thoughts :)[/QUOTE]

This a valid point and a big concern to big ships. If the SV average heading cannot be figured out, the tendency will be to play muscle.
So my advice for a SV getting into a close CPA with a big ship is to try to keep constant heading for longest time possible. Of course short and even large heading fluctuations can be expected over very short time periods but try to keep the average steady (at least ten minutes). A big ship is not going to alter course because the CPA changes every ten seconds, but a big ship covers at lot of ground in ten minutes and for many of them that is really decision time.

Good point about everybody having AIS and cluttering up the screen, it might get to the point where I only use class A targets and turn off class B. Also good to remember to switch from underway to moored when securing your vessel.

You said you wanted some advice. To start with how about following the Colregs. Start with having someone on watch.

p.s. Are you one of the idiots who sails with an anchor light on so that everyone can see them?

[QUOTE=Signal Red;113239]Good point about everybody having AIS and cluttering up the screen, it might get to the point where I only use class A targets and turn off class B. Also good to remember to switch from underway to moored when securing your vessel.[/QUOTE]

Class B can’t change Status for Moored/Anchored, or even NUC. The only change is dynamic where the speed drops below 2 knots the reporting age changes from 30 seconds to [B]three minutes[/B].
One idea was to get folks to turn the AIS off when docked… but many want theirs on so they can use Marinetraffic.com (etc) to track their boat if its knocked off.

Lastly, there is a bunch of new products out for recreational boaters that are like a PLB but transmit AIS. So filtering may be unreasonable. Also remember that New Zealand initiative replacing navigational markers with virtual AIS markers. The future may be so busy on the screens that some rationalisation occurs.