AIS Do I Need It?

[MYTraveler]

Originally Posted by Dockhead

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.

You don't need to know a bearing with precision to determine risk of a collision course -- all you need to know is whether the bearing is changing. For that, a hand bearing compass is not necessary or even particularly useful. If the other vessel appears to maintain a constant bearing, it should be regarded as a collision risk. Knowing that the bearing is actually changing, imperceptibly but for the hand bearning compass's precision, does not add useful information, in my opinion.

[Pelagic]

Familyvan I honestly never do that.... My simulator training discouraged making assumptions and that was
reinforced by reading so many formal reports of casualties caused by failure to properly assess a changing situation

My working philosophy..... , both my eyes (if in sight) and electronics must fully agree with my desired CPA until the vessel is well clear.

By setting that formal example, it was the only way I could teach my officers to be good watchkeepers when working on my ship.

[MYTraveler]

Originally Posted by DotDun

I despise sites like MarineTraffic/Shipfinder/Vesselfinder making money off my information.

I don't think the commercial users are paying to get your information -- they want to know where their fleet is.

[Sandero]

Originally Posted by MYTraveler

You don't need to know a bearing with precision to determine risk of a collision course -- all you need to know is whether the bearing is changing. For that, a hand bearing compass is not necessary or even particularly useful. If the other vessel appears to maintain a constant bearing, it should be regarded as a collision risk. Knowing that the bearing is actually changing, imperceptibly but for the hand bearning compass's precision, does not add useful information, in my opinion.

This correct and Dockhead is all wet about this.

[monte]

The reason a hand bearing compass is useful is because it can be rotated to determine the other vessels bearing. Line up the lubber line with the ship and monitor. Obviously not needed if the other vessels course is clear using less finite techniques, but definitely more accurate than an eye through the rigging of a moving sailboat, unless of course your sailboat doesn't move...

[MYTraveler]

Originally Posted by Jon Eisberg

Do you mean to say you wouldn't even bother to take the trouble to place a DSC call to the ship in question, for the purpose of determining the precise location of its transponder, "in order to more accurately assess the situation" ?

That could make all the difference in deciding whether to cross ahead, or to chicken out by taking his stern, no?

;-))

Transducer location is part of Class A info.

[MYTraveler]

Originally Posted by monte

The reason a hand bearing compass is useful is because it can be rotated to determine the other vessels bearing.

How does that help? For making contact -- if the other vessel is AIS equipped, you can hail by name or DSC. But if it is useful, wouldn't it be easier to add or subtract 180?

[FamilyVan]

Originally Posted by Pelagic

Familyvan I honestly never do that.... My simulator training discouraged making assumptions and that was
reinforced by reading so many formal reports of casualties caused by failure to properly assess a changing situation

My working philosophy..... , both my eyes (if in sight) and electronics must fully agree with my desired CPA until the vessel is well clear.

By setting that formal example, it was the only way I could teach my officers to be good watchkeepers when working on my ship.

Fair enough. We know doubt have identical simulator training because I believe we're both Canadian, good chance we even studied at the same schools if that's the case.

However, our background prior to that training may have lead to different philosophies. I was a quarter master (wheelsman) for well over a decade before ever standing a navigational watch, as I'm sure you're aware, a wheelsman generally isn't permitted the use of electronics beyond a Gyro or FOG.

The result of that background for me, is that I've never had much use for electronics, for me I just used them to verify my evaluation. I was popular with many skippers because I didn't rely too heavily on electronics. When I became skipper myself, I didn't care what any one else though

I am definitely not trying to contradict you or challenge your philosophy in any way. I'm just explaining mine.

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[monte]

Originally Posted by MYTraveler

How does that help? For making contact -- if the other vessel is AIS equipped, you can hail by name or DSC. But if it is useful, wouldn't it be easier to add or subtract 180?

Being able to rotate the hand bearing compass allows you to compensate for your own vessels course deviation and monitor the true bearing.

[Pelagic]

I agree that experience does help you to anticipate traffic and I credit my early days working the west coast especially fog bound BC and Alaska with honing my use of Radar techniques in a fairly well organized environment.

But as I ventured more into heavily congested Asian waters... the locally trained mariners on coastal freighters, would often surprise me with their aggressive actions on poorly equipped ships and fishing boats.

This developed my style of maintaining a very formal bridge team at all times and verifying escape corridors by ARPA Trial Maneuvers and the use of True Motion.

Insisting on a focussed bridge did not make me popular with the new watchkeepers at first.... but years later after they had experienced their own commands..... they thanked me for it.

[Jim Cate]

In my experience, use of a HBC is the only non-electronic method that works when one's own boat is not steering a steady course, something that happens in any sort of big seas. When your boat is yawing about, the canonical "sight over a stanchion" sort of technique doesn't work, but noting the compass bearing to a distant ship does.

The interesting discussions above with professional big ship skippers are based on the stability of such big ships, something that yachts often lack in reality.

Jim

[Dockhead]

Originally Posted by MYTraveler

You don't need to know a bearing with precision to determine risk of a collision course -- all you need to know is whether the bearing is changing. For that, a hand bearing compass is not necessary or even particularly useful. If the other vessel appears to maintain a constant bearing, it should be regarded as a collision risk. Knowing that the bearing is actually changing, imperceptibly but for the hand bearning compass's precision, does not add useful information, in my opinion.

The purpose of a HBC in collision avoidance is to detect CHANGES in bearing which are imperceptible to the naked eye. No one cares about the bearing itself.

If you can't see a changing bearing with your naked eye, this does not mean necessarily that you're on a collision course. He could be passing a mile ahead, or a mile behind. Maybe he already maneuvered to set up a safe crossing. Or he might be about to run you down. You can't tell. And lacking this information, you don't know what to do. Maybe he's passing behind, but since you can't tell, you make a hard turn to starboard - right under his bows. If you were using the hand bearing compass properly, writing down the bearings every two minutes for a while, you would have this information, and you would know the correct maneuver - which is often to hold your course and speed.

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[Dockhead]

Originally Posted by Sandero

Obviously you can't observe north with your naked eye because it is impossible to see! It's a construct. You can observe the motion of vessels and fixed things in the water with your eyes. And you can make judgements if your vessel is going to have a (too close) encounter...

A bearing is just as much a construct as is North. You cannot observe it directly, but only in relation to something fixed and far away (preferably as far away as the magnetic North Pole). In open water with only your stanchion as a reference, which is not fixed, but rather slewing around, and besides that, is only a couple meters away at best, you can see only enough to recognise courses very far from collision courses.

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[Sandero]

Originally Posted by Dockhead

A bearing is just as much a construct as is North. You cannot observe it directly, but only in relation to something fixed and far away (preferably as far away as the magnetic North Pole). In open water with only your stanchion as a reference, which is not fixed, but rather slewing around, and besides that, is only a couple meters away at best, you can see only enough to recognize courses very far from collision courses.

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Boats are moving platforms to make observations from... including celestial which is not easy on board in a seaway. However I, sitting in cockpit can pretty effectively site a vessel's "progress" by comparing it to a fixed stanchion for example on my boat and make a reasonable assessment of whether it will pass my bow or stern... or YIKES. If there is any doubt I take the stern and have had no problems with this approach in coast waters and between NE and the Carribean. I do recall being driven nuts by a vessel looking for a ESA launch first stage near the Amazon which was doing some sort of search pattern which I later figured out. It was dancing like a butterfly ;-) and I took a course well clear of its maneuvering.

I think we want to hone and keep sharp are basic seat of the pants tried and true low tech navigation skills and not lapse into relying on these fabulous high tech devices. I learned to DR, worked with paper charts and did offshore passages without GPS and I now use plotters all the time and my charts are not see the top of the chart table much. I am not averse to high tech.

I don't think MOST boats in most situations *need* AIS. And of course they did fine without it a number of years ago. It would be interesting to know if we have fewer accidents / incidents since the introduction of AIS? And where these changes were.

Keep it simple.

[El Pinguino]

Originally Posted by Jim Cate

In my experience, use of a HBC is the only non-electronic method that works when one's own boat is not steering a steady course, something that happens in any sort of big seas. When your boat is yawing about, the canonical "sight over a stanchion" sort of technique doesn't work, but noting the compass bearing to a distant ship does.

The interesting discussions above with professional big ship skippers are based on the stability of such big ships, something that yachts often lack in reality.

Jim

True enough.... we have/had access to toys smallboat sailors could only dream off ... 25 kW radars for one.

However , watching the compass bearing of another ship was - for me at least - a big ship practice..... eyeballing the relative bearing is a small ship skill ... you learn in time to factor in any yaw..

When anything gets half close to me the bearing better be altering pretty substantionaly.......

A thort.... when taking a bearing of a big ship do you take the bearing of the front, the middle, or the back end?

Close up you can have an opening bearing on the bridge and a steady bearing on the bow......

Ping... waiting on epoxy to go off....