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Old 15-08-2015, 04:31   #106
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Re: AIS Do I Need It?

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Originally Posted by Jon Eisberg View Post
. ..
As for me, being the Old School Wimp that I am, whenever I determine - sometimes with no more than a casual use of the naked eye, no less - I might be dealing with a collision course situation, I'll generally default to my trusty "I Think I'll Take His Stern" Mode…
In other words, rather than taking the trouble to make an accurate assessment of the situation, you just make for his stern? As one pro on here commented recently -- if you can even see his stern, there is no risk of collision at all in most cases (it depends on relative speeds). But without knowing whether or not the ship has already maneuvered and is passing you safely, or how he's passing you, you can't know what to do.

What do you do when he's bearing right down on you at four times your speed? And hasn't seen you? Your life could depend then on knowing whether he's passing ahead or behind to accuracy of maybe a couple of boat lengths (and maybe less than his beam).

A lot of cruisers don't share space with ships in open water. The ships they see are following channels or fairways and are easy to avoid without any special knowledge or technique. So this discussion is not relevant to everyone.
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Old 15-08-2015, 05:05   #107
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Re: AIS Do I Need It?

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Indeed. Common sense always and eyes usually, but for some things you need more - knowledge and skill. Eyes and common sense won't get you safely through a fog bank, and they won't get you out of a collision in open water, either - for that you need knowledge and skill, and at least a hand bearing compass.

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I'm not sure I fully support the hand bearing compass theory, I don't even have one on board. For a good mathematical solution to collision avoidance they help, but I'm not usually too interested in a mathematical solution.

If I'm the give way vessel, and I can deduce that I'm going to be crossing roughly 2 or 3 miles ahead of a large commercial vessel at sea, then I point my bow in a different direction, normally towards his stern.

These days I have my CPA alarm which gives me an early warning that I will be closer than desired to a passing vessel, which is great, but I still don't calculate a mathematical solution to the problem, I can, but I don't.

Mathematical solutions are great tools in your chest, but I believe the greatest benefit in learning how to calculate CPA and course or speed to achieve desired CPA (which was done on a RADAR plotting sheet when I studied) isn't the resultant mathematical solution, but the increased understanding of how ships interact on the water.

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Old 15-08-2015, 05:07   #108
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Re: AIS Do I Need It?

Arguing against AIS because some ships don't use it seems like arguing against installing a radar reflector because some ships don't keep a good radar watch.

Fiberglass sailboats are notoriously diificult to see on radar. In heavy seas or rain it's almost impossible. Why would you NOT want a 300 meter container ship approaching you at three times your speed to be absolutely sure of your posistion and course?

And it's naive to think that large ships monitor radar as carefully as they did before AIS became the primary anti-collision tool.

Being run down by a large ship is my #2 sailing nightmare ( falling overboard is #1). An AIS transponder is the best protection I know.

.
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Old 15-08-2015, 06:46   #109
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Re: AIS Do I Need It?

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Originally Posted by Dockhead View Post
Indeed. Common sense always and eyes usually, but for some things you need more - knowledge and skill. Eyes and common sense won't get you safely through a fog bank, and they won't get you out of a collision in open water, either - for that you need knowledge and skill, and at least a hand bearing compass.
In fog, other senses come into play... Your ears, certainly, and often your sense of smell, as well... Unfortunately, with fog often comes little or no wind, but when at all possible, I think sailing in fog is generally preferable to motoring, as a rule, and why you want to be doing so from an open cockpit, as opposed to from 'inside' some form of enclosure, to better appreciate whatever subtle indicators being sent your way...

In my observation, one of the unfortunate consequences of the nearly universal use of AIS nowadays, might be the fact that virtually NO ONE seems to be sounding fog signals while underway any more... I spent a lot of time running in fog last summer, and I can't recall encountering a single vessel that was making continuous use of their fog horn...

One thing I have never understood, is how rare it is to see a permanently installed horn on sailing vessels of the size most of us sail... Virtually every powerboat of any size can produce a horn signal at the push of a button. Yet I'd guess if we took a poll here as to how many of our boats are equipped to produce a proper fog signal for days on end, I'd bet very few hands would be raised... ;-) Even a box full of canned air horns and a stopwatch, ain't gonna cut it...

One of the more amusing remarks I got last summer, was from some workers at the fish plant in St. Mary's Harbor, Labrador, on the morning after I had gingerly worked my way in the evening before, in the very heavy fog that had bedeviled me for several days... "Yeah, we heard you approaching yesterday for a couple of hours, and were beginning to wonder whether you'd EVER make it in here..."

I'll bet the beluga who befriended me in St. Mary's, and circled about my boat all night long, heard me coming, as well ;-)





Frankly, I'm not sure which prospect is more frightening... Knowing a gigantic Maersk container ship is steaming @18 knots a mile away in heavy fog without sounding a fog signal, or actually HEARING that booming, bone-chilling sound of a prolonged blast of the horn from such a vessel...

;-)
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Old 15-08-2015, 06:47   #110
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Re: AIS Do I Need It?

Yes you need it. Ifyou’re cruising you are making extended night crossings in traffic lanes. Probably shorthanded. AIS will let you see, identify track, forecastand communicate with targets that are threats. With the low cost of receiving units that can be networked into yourchart plotter it just makes good horse sense. Transponder units are more expensive and rely on the other guymaintaining a watch. Radar requiresconstant attention, supplies less info but still has its place at your navstation.
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Old 15-08-2015, 07:33   #111
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Re: AIS DO I NEED IT.?

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I'm not sure, we have much stronger privacy laws up here. I am not aware of a public database for boat registries. As far as I know though, MMSI numbers are searchable, which of course will be transmitted by your AIS. I'm not as concerned about people finding out who I am as just the general hassles of a Coast Guard "safety check".
Vessel Registration Query System

It's handy for checking into other countries and proof of ownership. Privacy vs convenience, where do you draw the line?

I'm sure we'll be laughing at this thread in six months when Garmin introduces their radar dome with built in GPS antennae and AIS transponder.

Hello, Garmin are you listening?


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Old 15-08-2015, 08:11   #112
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Re: AIS DO I NEED IT.?

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Originally Posted by Ann T. Cate View Post
I do not like ours' placement, it's too bright. Might be okay in highly lit areas, but on the open ocean, its dimmest setting is too bright for my vision. I'd rather have to go below to check it.Ann
Ann,

The transceiver I was looking at, the Vespar unit is just a box, nothing on it to look at. What exactly is yours? Does it have a LED display of the AIS traffic?
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Old 15-08-2015, 08:24   #113
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Re: AIS Do I Need It?

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In fog, other senses come into play... Your ears, certainly, and often your sense of smell, as well...


Honey, I smell bacon. Are you frying bacon???

Holy CR.... Bacon off the port bow...

CRUNCH.....

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Old 15-08-2015, 08:50   #114
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Re: AIS DO I NEED IT.?

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The point is that it is not the slightest overstatement. In open water you must use at least a hand bearing compass, in order to detect a risk of collision in time to do anything about it - in cases where difference in speed is double or triple or more.

If you do not understand how this works, and do it, then you are 100% dependent on two things - luck, and the ship's ability to see and avoid you. These two things maybe work most of the time, but what if he's taking a leak below, or is distracted, or just doesn't seem you?

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That is not true. I can tell whether I am going to pass in front of behind or collide with a vessel using only my eyes from a static position on my boat.
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Old 15-08-2015, 09:27   #115
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Re: AIS Do I Need It?

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Quote:
Originally Posted by El Pinguino

I can't remember when I last used a hand bearing compass to check if a ship was on a steady bearing when navigating, etc visually.... easy enough to do it without one.
Not at 5 to 8 miles out you can't. It's not easy even with a HBC. You can get the roughest approximation by using a stanchion as a transit, but the accuracy of that depends on a very steady heading.
Could be just me, but I might have to start drinking pretty early in the day to summon the nerve to tell a guy like The Penguin what he is, or is not, capable of doing at sea…

;-))

You do realize that even the accuracy of the information given by AIS - at any given moment of time - is also dependent on a steady heading as well, right? Sure, AIS is pretty good at 'averaging out' relative bearings if you stare at the screen for awhile, but I find a hand bearing compass can be pretty damn useful when in doubt, and your boat's heading might be all over the place in a seaway...
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Old 15-08-2015, 09:43   #116
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Re: AIS DO I NEED IT.?

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Originally Posted by jwcolby54 View Post
Ann,

The transceiver I was looking at, the Vespar unit is just a box, nothing on it to look at. What exactly is yours? Does it have a LED display of the AIS traffic?
Here is a Vesper transponder with display:

(WatchMate Vision AIS Transponder | Vesper Marine)
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Old 15-08-2015, 09:46   #117
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Re: AIS Do I Need It?

Quote:
Originally Posted by Dockhead View Post
Quote:
Originally Posted by Jon Eisberg
. ..
As for me, being the Old School Wimp that I am, whenever I determine - sometimes with no more than a casual use of the naked eye, no less - I might be dealing with a collision course situation, I'll generally default to my trusty "I Think I'll Take His Stern" Mode…
In other words, rather than taking the trouble to make an accurate assessment of the situation, you just make for his stern?
Nah, it's no "trouble" at all to make a more accurate assessment... But I trust my general ability to judge speed and distance on the water, and if at first glance it appears I might have an issue with another vessel, my usual initial inclination will be to start thinking about taking his stern...

One of the most useful things about AIS, in my view, is that it can serve as a very useful check in assessing whether my ability to judge speed, angles, and distance is still as sharp as it was when I was a kid racing dinghies, and had nothing but my pair of Mark I eyeballs at my disposal...;-)

Quote:
Originally Posted by Dockhead View Post
What do you do when he's bearing right down on you at four times your speed? And hasn't seen you? Your life could depend then on knowing whether he's passing ahead or behind to accuracy of maybe a couple of boat lengths (and maybe less than his beam).
Seriously ???

Well, all I can say is... If the ability to determine whether a container ship is gonna cross your bow to within a few boat lengths - or your stern by a similar margin - is going to make even the SLIGHTEST DIFFERENCE in the course of action you're gonna decide to take, well.... then you are a FAR braver man than I...

;-)
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Old 15-08-2015, 10:00   #118
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Re: AIS Do I Need It?

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Do cruiser need AIS and if so what should I get?

Location: Tin Can Bay, Queensland, Australia
Boat: Cloud Catamaran, Cloud 9, 10.6M, Rainbow Dreaming
Flat answer regarding 'Need' is NO. You can sail perfectly safely without if you are careful.

Whether it will be "very helpful" depends on where you will sail . . . higher shipping density will mean more helpful. Take a look at the follow picture . . .

Click image for larger version

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Your immediate part of the world I would characterize as 'medium density' and you will probably find it occasionally useful. But if you go into asia (especially around Japan) or toward the red sea, you will find it rather useful. In the south pacific . . . not so much. Below 40 S, pretty much not at all.

Regarding what to get - you have two options to consider: (1) is transmit or not . . .I would suggest you definitely want to transmit. You want them to see you so they can take avoiding action. (2) black box or with own screen . . . It just depends on how your nav station is set-up. If you already have a good plotter screen which you can feed AIS info to, then go black box . . . if you don't have such a screen get an AIS with one. The Vespers have excellent models of both.

DH . . . you know I am a fan of AIS . . . . but IMHO you are being unreasonable saying that people CANNOT do collision avoidance by eyeball. It may well be harder, but people did it for years (before AIS and also before recreational radar) and many still do it . . . and collisions with ships are extremely rare (and almost always happened when people were not paying attention, rather than because they were paying attention but 'could not' make an accurate assessment). When using eyeballs you simply take earlier and more significant action when you judge there is the risk of a collision.

I might note that the use of AIS actually increases the risk of two types of collisions. (1) people with AIS tend to use smaller margins of error and if something completely unexpected happens may well not have enough margin to recover; and (2) people are sometimes (often when tired at 2am) for get that the screen does not reflect full reality and stop looking around at the real world, and hit something not showing clearly on the screen (perhaps not showing on either radar nor ais screens). Both of those are 'operator error' and not truly the 'fault' of the equipment, but the equipment does allow/encourage that sort of sloppy behavior.
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Old 15-08-2015, 10:04   #119
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Re: AIS Do I Need It?

During the past three years since we first installed our AIS receiver, we've only needed to contact another vessel one time. At night a large ferry appeared to be heading directly at us from 6 miles away, we first spotted the ferry 8 miles out on radar and began tracking it. The conversation basically confirmed what we already knew. When asked if they could see us.... "No problem, we see you just fine.... Please don't worry about a thing." And they passed us 1/2 mile off our stern.

With our radar reflector, we are very visible. Using only our eyes and radar, nothing sneaks up on us. We can tell if a vessel is going to pass us via the stern or off the bow without a compass using just our eyes and have plenty of time to take evasive action... Which is to always allow the faster, larger vessel to pass ahead of us. If AIS did not exist... I think we would be fine.
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Old 15-08-2015, 10:33   #120
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Re: AIS Do I Need It?

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With our radar reflector, we are very visible.
Pardon the drift, but since you bring this up, what type/model/brand reflector are you using?
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