AIS, Receiver or Transmitter

[El Pinguino]

Originally Posted by Dockhead

Even in perfect visibility, you cannot distinguish a safe crossing a mile ahead from a safe crossing a mile behind from a collision course, with your bare eyes, from 5 miles away, and you can't tell anything at all at 10 miles, when the other vessel will be hull down........

Oh yes I can, you may not be able to but I can.....

[weavis]

Originally Posted by El Pinguino

Oh yes I can, you may not be able to but I can.....

Gosh! My hero!

just joshin' Ping...

[El Pinguino]

Originally Posted by weavis

Gosh! My hero!

just joshin' Ping...

Can't be too hard as I'm not the sharpest tool in the shed.... mind you 53 years and 6 months of practice helps a bit....

[Dockhead]

Originally Posted by weavis

As a boat user, I see this discussion a slightly different way.
I do NOT ever feel morally obligated to purchase a piece of kit and use it. I purchase it because Im forced to or because I need it.

My boat has RADAR. I use it when I want to, for my knowledge and needs, not for anyone else. I carry crew at times and they inform me of sightings for my knowledge and adherence to Colregs.

I use AIS for my knowledge and information. I dont have TX. Does this mean I cannot use it? No.... Does this mean I am against having a TX unit? No... it means I dont have it plain and simple.

There is no moral obligation that I will accept to force me into buying a unit. Do I think its a help? In the right area yes, and where legally obligated to have.

Is it better than RADAR? Its different.

If its a moral issue then manufacturers should morally drop the price. Why should they benefit from something that everyone 'should' have?

I like AIS... one day I will have TX but like everything else, its an add on not a replacement. I dont have the luxury of buying everything at once... sometimes its one thing or another....... for those of us on a budget, families, children, student loans, job insecurity you will know what I mean.

I like it... but please stop with forcing everyone to get one.... its the thin edge of the wedge and making an expensive hobby even more expensive.

If I NEED it to sail then sailing has lost out...

Who's forcing? Do you have a good radar reflector?

Ships don't really need your AIS data -- they have very powerful radars with ARPA which actually works (unlike on our radars).

The professional mariners I know ALL say that radar and ARPA is still the primary collision avoidance tool and is at the heart of all their procedure. They use AIS more and more as a supplement, and some bad crews forget proper procedure and over-rely on it like some of us do, but crews following proper procedure look at radar first.

You will help other recreational sailors a lot if you broadcast AIS, but collision avoidance with small boats is much less complex.

And as we've discussed, different sailors sail in different waters, and not everyone does much high seas collision avoidance anyway. Some people don't even know what it is.

[daletournier]

I really dont get the AIS argument. There's just no downside other than purchase price. Where I have found it very valuable is at night ,particularly if youve been at sea for a couple of day's and tiredness creeps in. It takes the guess workout of knowing exactly where a ship is and where its going. Secondly it gives you the ships name, calling up a ship by its name seems to always get a response. You would think that in the middle of the ocean with all that room that ships and yachts would never come close, well in my experience there seems to be a magnetic attraction between the two. Also there has been quite a few times that ive radioed a ship (by name) to ask if they have seen small sailing vessel that they are closing in on, only to recieve a reply that indicates they have not.
For me its an essential part of kit, no downside all upside. It takes the guess work out of a potential collision.....absolute no brainer.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[Dockhead]

Originally Posted by El Pinguino

Oh yes I can, you may not be able to but I can.....

You may think you can, but I guarantee you, you cannot. These situations are absolutely indiscernible by the naked eye. You can no more do that, than you can identify an e coli bacterium, without a microscope.

Not knowing what you don't know, and not knowing what you can't perceive, is one of the most dangerous things to us.

Shall we bet on it? I'll give you good odds -- 10:1?

Just go out on someone's boat with AIS and look at some ships at 10 miles and at 5 miles. Give your friend your bare eye assessments and let him check by AIS.

You are welcome to do it on my boat if you find yourself over here.

[daletournier]

Originally Posted by Dockhead

You may think you can, but I guarantee you, you cannot.

Not knowing what you don't know, and not knowing what you can't perceive, is one of the most dangerous things to us.

Shall we bet on it? I'll give you good odds -- 10:1?

Just go out on someone's boat with AIS and look at some ships at 10 miles and at 5 miles. Give your friend your bare eye assessments and let him check by AIS.

You are welcome to do it on my boat if you find yourself over here.

DH is 100% on the money, you cant. Throw some sleep deprivation in there as well as darkness and see how you.go.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[El Pinguino]

Can I tell you if she shall pass 1 mile or 1.1 miles ahead? No...
Can I tell if risk of collision exists and if the ship shall be passing closer than I am comfortable with... yes.
People have been doing it since Noah was a deck boy.

[weavis]

Originally Posted by Dockhead

Who's forcing? Do you have a good radar reflector?

Ships don't really need your AIS data -- they have very powerful radars with ARPA which actually works (unlike on our radars).

The professional mariners I know ALL say that radar and ARPA is still the primary collision avoidance tool and is at the heart of all their procedure. They use AIS more and more as a supplement, and some bad crews forget proper procedure and over-rely on it like some of us do, but crews following proper procedure look at radar first.

You will help other recreational sailors a lot if you broadcast AIS, but collision avoidance with small boats is much less complex.

And as we've discussed, different sailors sail in different waters, and not everyone does much high seas collision avoidance anyway. Some people don't even know what it is.

Yes I have reflectors... I light up like the QEII on their screens..

The downside to AIS is unfortunately the price... One day it will be cheaper and probably integrated with a Jacuzzi and gimballed oven.

[El Pinguino]

Originally Posted by daletournier

DH is 100% on the money, you cant. Throw some sleep deprivation in there as well as darkness and see how you.go.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

Darkness? 50% of my watchkeeping life was spent in darkness....

Back on track... it would appear in this thread that 100% of those with AIS TX think it is worthwhile..... the only people who don't think it is a worthwhile investment ( the OP's question if I recall correctly ) is them as have never used it.

Moving right along....some years back ( pre AIS)... reasonable amount of crossing traffic... clear vis... black as the inside of a cow....... the radar with arpa dropped its bundle... we still had a #2 non arpa radar.... new ink still wet on his ticket 3rd mate did not have a clue what to do or how to manage without it..... sad really how simple skills are lost....

[Dockhead]

Originally Posted by El Pinguino

Can I tell you if she shall pass 1 mile or 1.1 miles ahead? No...
Can I tell if risk of collision exists and if the ship shall be passing closer than I am comfortable with... yes.
People have been doing it since Noah was a deck boy.

Ah hah, so now we drill into it.

Yes -- you can tell very wide safe pass if you can see a changing bearing with the naked eye. But that is not at all the challenge.

But you can't tell anything at 10 miles when the primary maneuvering takes place.

And you can't tell even at 5 miles whether he has changed course or not to make a safe pass of 1 mile or not.

That's my whole point. Here's a scenario:

1. Ship approaching from your port side sees you at 10 miles. With ARPA it sees that it will pass 1 mile ahead of you, so holds course and speed.

2. You notice him at 5 miles, but with your bare eyes, you can't perceive any changing bearing, so you have to assume that you have a problem.

3. So now you prepare to change course yourself, but you don't know which way to turn, since you can't tell whether he's passing ahead or behind. So you follow correct procedure and alter to starboard.

4. You just changed a 1 mile CPA to a 0 CPA, and you might be 3 or 4 miles from CPA before he notices it.

You've just created a dangerous situation with little time to deal with it, out of a perfectly safe pass -- due to lack of information you could have had from AIS.

And

5. You wouldn't do this, Ping, as you are a highly experienced and skilled mariner, but how many amateurs will see that the alteration to starboard didn't solve anything, panic, and stop, or make a hard turn to port, just as the ship is making a hard turn to starboard?


I hope this illustrates how the Mark I Eyeball does not give you the information you need, to do collision avoidance.

But everyone should know that -- we will all have been taught to use a hand bearing compass for this, not your bare eyes. This is Sailing 101; you probably can't get a Competent Crew paper without knowing this.

With a hand bearing compass, we will have an order of magnitude better information and can handle the scenario above successfully. At 5 miles with a HBC you indeed can distinguish 1 mile ahead vs collision course vs 1 mile behind and will know to hold course and speed, and will know -- because you can see a slow increase in his bearing, that he is passing ahead, so you will know not to alter to starboard.

[Dockhead]

Originally Posted by El Pinguino

Darkness? 50% of my watchkeeping life was spent in darkness....

Back on track... it would appear in this thread that 100% of those with AIS TX think it is worthwhile..... the only people who don't think it is a worthwhile investment ( the OP's question if I recall correctly ) is them as have never used it.

Moving right along....some years back ( pre AIS)... reasonable amount of crossing traffic... clear vis... black as the inside of a cow....... the radar with arpa dropped its bundle... we still had a #2 non arpa radar.... new ink still wet on his ticket 3rd mate did not have a clue what to do or how to manage without it..... sad really how simple skills are lost....

I always found collision avoidance in the dark to be much easier, especially before I had AIS.

That's because all the extraneous visual information is stripped away, and you can see his nav lights. It means you instantly understand his aspect -- something maddeningly difficult to perceive in daylight at long distances.

Much easier to take a bearing on a nav light than on a vague shape of his hull.


MARPA is utterly useless on all the crappy recreational radars I've ever had, so I never used it for collision avoidance. Before AIS, I used (and that's what I would have done on your ship, if the ARPA had gone down) -- the EBL. Just put the EBL on the target and you see in just a few sweeps how you're crossing. If he's walking down the EBL then you know you have a problem. This works even with our crappy recreational radars with very poor bearing discrimination, as the bearing errors will average out over a few sweeps.

But the hand bearing compass is probably even better. Didn't you have them on the bridge of your ship?


My next boat will have a 20kW open array radar. I love AIS (you couldn't tell, could you?) but it by no means replaces radar, even in some collision avoidance situations.

[MarkJ]

Originally Posted by El Pinguino

Oh yes I can, you may not be able to but I can.....

What a fool response. I can, you can't so AIS is useless.

Just typical forum b.s..

Ping, you bring great stuff to this forum so I am quite shocked at your attitude on this.

[Dockhead]

Originally Posted by MarkJ

What a fool response. I can, you can't so AIS is useless.

Just typical forum b.s..

Ping, you bring great stuff to this forum so I am quite shocked at your attitude on this.

Hey, let's stay calm here. I didn't read Ping as saying that at all. Read his further posts.

[El Pinguino]

Gee DH, I really do wish I could touch-type like you but since that encounter with the croc up the Rio Pongo all those years ago I just have to peck away at the keyboard with my remaining digits.

Simple thing is that you said collision avoidance couldn't be done by eye... a rather sweeping statement.

I love all the fancy new kit but can and do live without it ( I have AIS but do I scuttle off down below to figure what is going on on a fine clear day? Nope..) ... but I would like to think that people understand that one can live without it.

HBCs on big ships? No... you have gyro repeaters on the bridge wings to watch the bearing with ( sadly many ships these days have fully enclosed wings... not a good thing in my opinion.)

I have an HBC on my little ship... don't use it... get enough info lining object of interest up with shrouds etc or even inshore watching how the ship I am concerned with is moving against the land.. then you have to factor in the distance of the land and its apparent movement.....

Let me tell you a little story about the 'good old days', 1971, watchkeeper on a 100k dwt tanker running PG/NWEurope...and PG/Japan.
A big enough ship for the time... 200k was not uncommon and there were even half a dozen 300k tankers.
Less than a year old, norwegian owners, swedish built.
Bridge kit? Two non gyro stabilised radars.... management was controlled by the 'plumbers'... they said 'this is what we have always fitted'.
Plotting targets on the radar to work out CPA involved chinagraph pencils and a reflection plotter fitted over the top of the PPI.... mark target ever 6 minutes.... construct vector thingo after 12 minutes... hope other party hadn't done anything in the meantime... work out CPA by extending line.

As display was not gyro stabilised if you altered course you had to start again from scratch.

So... unless you couldn't see the focsle ... everything was done by eyeball... English Channel, Hormuz, One Fathom Bank, Singapore Strait, all done by eyeball, the brain filter, and the gyro repeater....

Not perfect but eyeball does work.....

I bet none of this lot on my doorstep have AIS