Freighters vs. Sailboats

[Richard5]

Originally Posted by Lodesman

Rule 10(d)(i):

I certainly have to get on top of current ColRegs, et al but as I am currently landbased and not venturing out on even day sails I haven't spent time with the regs. As an aviator I have committed to memory 14CFR and some ICAO where applicable. Before I take to the waters again I will become familiar with ColRegs, et al. One thing I have found helpful is knowing the history of the regs, at what point in time did this or that part come into being, etc. When did the above referenced part come into being?

Sounds like you were between a rock and a hard place, and this guy cut the corner, contrary to the rules. I would guess you didn't paint on his radar. Is there a VTS in place there?

That is an accurate summary. While not quite hugging the coast of the islands we were on that side of the multiple traffic when transiting that area. But this one ship was further to the south in this west/east channel. While that wasn't much of a big deal, it was when he cut so finely the corner to come to a new southerly heading which was the big surprise. And now that I have again been thinking of that event, I am fairly certain I did try several times to call him on the VHF of which no response was received. It was my SOP to attempt radio comm so it follows I would most certainly have made the attempt. But I also remember how trying it can be when attempting to communicate with non-English speakers. I tangle with these sorts in the air from time to time and it can be extremely exasperating for all especially when they don't stick to their stated intentions.

If by VTS you mean picking up local pilots I would say no. They pick up a pilot when much closer to the ports, ie, further south. If you mean traffic control, I confess ignorance. I would say I seriously doubt that control would be available to traffic that far north of the ports. The body of water in question is at least 100 nm to the north of the ports but within VHF range of the coastline. SSB or teletype or marine operator would certainly be within range. I confess to not possessing an intimate knowledge of merchant marine operations.

[Seaworthy Lass]

Thanks for the considered response Lodesman.

Originally Posted by Lodesman

Honestly, I don't think I'd go to your table to figure out if risk of collision exists. That's not to say I can't see of some utility. Perhaps it would be a good instructional tool - obviously some people can't wrap their heads around relative motion and when risk of collision can exist. .

I don't see the table as just an instructional tool, although it is eye-opening how narrow angles occupy half of it (I think even Cappy was surprised how narrow the angle was if the freighter speed was at least 3 times that of the yacht, which I think is the most common occurrence).

I don't see this table as being the first tool used either. If you are relying on manual methods, HBC and line-of-sight are much better techniques. If you have AIS or MARPA they are of course better again.

But, the table does give info not available from any of the above 4 methods.

I think it may be particularly useful to determine BEFORE you make a change of course/speed whether it is safe to do so and by how much. AIS and MARPA will only tell you this AFTER you have made the change and re-established the new speed and heading.

This may be critical if you are trying to dodge multiple freighters at the same time and you want to make a correction as soon at is is safe to do so. The information is very reliable if you are plugging in AIS or MARPA data rather than making estimates.

Here in the Med there are occasionally 6-10 freighters within a 12nm range and dodging becomes an essential skill. Even if the table needs to be used infrequently, if kept in easy reach under the dodger it may be invaluable in some situations.

Originally Posted by Lodesman

Or perhaps it could be used to show newbies that they don't have too much to worry about being a slow vessel out on the marine superhighway - seeing that the danger zone in front of a fast freighter is a surprisingly narrow piece of the pie. .

I would not want them to get any sense of complacency! I think that is what Cappy was concerned about. The yacht may be narrow off the freighter's bow if the speed of the freighter is at least 3 times that of the yacht, but this is not always the case and the freighter can still be approaching from 360 degrees, so a vigilant lookout is essential.

It may give the freighter some sense of complacency regarding looking out for yachts if his speed is high, but it should not effect the complacency of the yacht at all.

Originally Posted by Lodesman

You might want to test it in the real world and get back to us.

I certainly plan to test it out and others may like to do so as well.

It will have to wait though, the meltemi is blowing and the current anchorage is blissful, so we won't be on the move again for a while .

[cappy208]

I was surprised by the 20 knot cone of death. But, what surprises me more is the apparent assumptions people are willing to make to assess risk of collision. Knowing full and well why most sailboats turn off all electronics while on an hours long sail, I get that. But to think you can determine a ships speed from eye while off in the distance (while the ship is heading directly at you) is pretty ballsy.

This is a great educational tool But I see most ships speed being between 12 and 16 knots. I am surprised at the several comments that 'their' sailboats do 4 and 5. I know I would be pretty xxxxised off if I was plodding along doing that on an afternoon daysail! Then again, I would opt to NOT go on a afternoon drift like that anyway :-)

AIS Data is derived (own vessel from your GPS data input) and other vessel (from their data input) That is as good as it gets.

ARPA data is derived from own vessels data, then used computer calculations to simulate the other Pips resulting data. ARPA is time dependent, and needs both vessels to be on same course for at least 3 minutes.

AIS is only needing heading, speed info for the filters to adjust, and it spits out the new info as soon as it retransmits.

Someone posted a couple dozen questions ago, that AIS is not accurate plotting the icon on a plotter or an interconnected RADAR.

There are several possible reasons. First, it depends upon HOW the AIS is set up. No one here can police all the AIS installations to ensure proper setup.

Class A AIS transmit about every 10 seconds while in 'underway' setting. When moored, it switches to (I can't remember the exact number) between 10 and 30 minutes. AIS class B transmits only every 10 minutes.

So you can see that if a vessel has a class B they will always be UP to 10 minutes lagging in their data presentation.

The last portion of why the informtation displayed is not 'spot on' is there is an adjustment on all plotters, and radars to induce 'offsets' to correct for small errors.

For instance, on my tug I had to put in a 00degrees, 00 minutes, .003 minus (meaning easterly) corrrection. The north south was right on. But any time i was sitting at a dock which was north south, i was always ON the dock, by half a boat width. So introducing the easterly corrections makes me sit where i should, when along side.

(BUT this is not always reliable, since most charts are a little out of whack in some places, no matter how good the government printing is.)

You have to carefully observe your position relative to many objects to determine if your position is off, an whether to correct it, or live with it.

[Lodesman]

Originally Posted by conachair

That sounds like a contradiction. - aren't CPA and TCPA derived from course and speed reported on AIS and your own GPS course and speed, if you have reasonable faith in the data then why not have reasonable faith in the CPA? It's just the box doing the work for you.

As Paul said, I would trust the freighter to maintain a reasonably steady course and speed, but a small sailboat's course and speed are lot more variable - that's a theme that's been repeated over and over in this thread. Perhaps if you're able to stabilize your own data somewhat as Paul suggests, the CPA/TCPA calculations won't bounce around so much, but it would still be predicated on the wind holding steady for the hour or so that you're closing.

I have not yet had the chance to use AIS in anger, but I'm well aware how much GPS Co/Sp can jump around (even in fairly large vessels). Maybe some with real-world experience with AIS will chime in, but I imagine that most AIS systems calculate the CPA/TCPA on a periodic basis with the data as reported at that instant rather than your average course and speed. As such I would follow IMO guidance and only use AIS as an informational tool and not rely on it for anti-collision.

[cappy208]

Regarding the AIS data. I am not familiar with ALL AIS, but the ones I have seen have settings which must be chosen on 'how to display' targets.

I know the ones I have used are set up to display the most dangerous targets first, not necessarily the nearest. And I do believe this is NOT factory settings. I think this is a decided setting to choose.

This would sort of take the wind out of the comments that 'too many small boats' would clutter up the ais info. I LOVE all boats having AIS. (But the class B stinks because of the time lag) But having some indication of a vessel out there is better than none.

Many large vessels are being required to post accurate voyage dynamic data on their AIS system. Many times the posted information is out of date or just wrong. The static data never changes, but dynamic data changes with each trip, POB, draft, destination, eta. I am unsure why the POB or eta would matter to yachters, but all the rest is pretty important. (especially if running near shoal water, or channel.)

[cappy208]

When RADAR first came out in commercial sets, it was hailed as the 'miracle' cure for ship collisions. But strangely enough, they kept having collisions. (think AndreaDoria/ Stockholm) Then every one started realizing that what is being seen on the RADAR screen is NOT actually what was happening in real life. Courses that boats 'appear' to be going and speeds are NOT true courses and speeds. When you 'look out' at other traffic you are not 'seeing' the actual information. Even those trained in the Radar Theory have to go back every 5 years for a refresher to maintain accredation.

(Which should be an alarm to the dependence on the graph to determine if 'risk of collision exists'.)

The understanding of relative motion was figured out and what is being displayed on a radar screen is Relative Motion, and Seamen needed to be educated on Relative Motion when operating RADAR.

[Lodesman]

Originally Posted by Richard5

One thing I have found helpful is knowing the history of the regs, at what point in time did this or that part come into being, etc. When did the above referenced part come into being?

If by VTS you mean picking up local pilots I would say no. They pick up a pilot when much closer to the ports, ie, further south. If you mean traffic control, I confess ignorance.

Cockcroft is a bit vague, but I believe that rule was in the 1972 conventions, and was amended in 1989 - I don`t know when it was adopted by the US.

VTS is Vessel Traffic Services - it`s a good idea to keep a listening watch on that channel if able as part of a good lookout. They can help identify traffic for you, or hail them when they don`t respond to your hails. I don`t know about other jurisdictions, but in Canada, VTS monitors the common VHF channels and if they`re not busy will listen in when two vessels switch to a `working`channel. They also record VHF and radar for a period to aid investigations. You can always report such an incident to the Coast Guard. More importantly, if VTS is monitoring the situation and you are hit or swamped, they`ll raise the alarm with the CG.

[psneeld]

1967 - Dover Straits TSS established

The Institutes in 1966 published a report proposing traffic separation schemes in a number of areas, and in June 1967 a traffic separation scheme was established in the Dover Straits - the world's first - and a significant fall was seen in the number of collisions between ships on opposing courses.
At the time, observance of the schemes was voluntary, but in 1971 a series of accidents in the English Channel led to calls for immediate action - in the most serious incidents, the tanker Texaco Caribbean was in collision with a freighter off the Varne shoals and the following night the wreck was struck by the freighter Brandenburg, which also sank. Some six weeks later, the freighter Niki struck the wreckage and sank with the loss of all 21 people on board.
As a result, IMO's Maritime Safety Committee meeting in March 1971 recommended that observance of all traffic separation schemes be made mandatory and this recommendation was adopted by the IMO Assembly later the same year. The Dover Stratis scheme was therefore the first mandatory traffic scheme, from 1971.
The Conference which adopted the Collision Regulations (COLREGs), in 1972 also made observance of traffic separation schemes mandatory.
Since then, numerous ships routeing systems have been adopted and they can be found in the publication, Ships Routeing.

IMO | Ships' routeing

[cappy208]

This story of VTS, TSS and all reminds me of a story.

I was about 50 miles south of Long Island, off the NY coast.

About 0300 I hear a frantic call to the CG about: "This big ship almost hit me"

The end of the story was, when he relayed his position to the CG, (which he was hanging onto a fishing gear buoy) I plotted it. He was directly IN the middle of the Ambrose to Nantucket Safety Fairway Separation Scheme. He had NO idea not just IF he was in a TSS, But he was clueless as to his position, where he was, and where he was on a chart. The only thing he was certain of was: This ship almost ran me over.

[chrisjs]

Regarding my earlier post about TSS between Block and Newport, my statement was clearly mistaken. And I do know that there are shipping lanes as were pointed out in subsequent posts. And you had better believe that crossing the Ambrose at night, we are very very careful!! But the story as originally told occurred between Block and the Narragansett West Passage where there is no TSS. In answering previously I had only considered (the lack of) shipping lanes in that vicinity because the freighter involved was headed from Buzzards Bay to Long Island Sound. In fact, I would estimate the majority of large traffic in this area, including barge tows, travels from BB toward LI Sound, not in the TSS tracks.That's my story (excuse) and I'm sticking to it!!

[cappy208]

Originally Posted by chrisjs

Regarding my earlier post about TSS between Block and Newport, my statement was clearly mistaken. And I do know that there are shipping lanes as were pointed out in subsequent posts. And you had better believe that crossing the Ambrose at night, we are very very careful!! But the story as originally told occurred between Block and the Narragansett West Passage where there is no TSS. In answering previously I had only considered (the lack of) shipping lanes in that vicinity because the freighter involved was headed from Buzzards Bay to Long Island Sound. In fact, I would estimate the majority of large traffic in this area, including barge tows, travels from BB toward LI Sound, not in the TSS tracks.That's my story (excuse) and I'm sticking to it!!

If that is your story, then you had better go back to the nautical charts and familiarize yourself with the magenta shaded areas, the Pilot warning areas and the Light Green shaded "Deep Draft recommended" traffic lanes. While not TSS, they are specified and ON the charts. It is amazing how many people are completely unaware!

"That's my story (excuse) and I'm sticking to it." That would be a good epitaph.

[CaptainDana]

Originally Posted by Lodesman

Flag Golf?

Flag Uniform.

[chrisjs]

Cappy:
The original discussion was about TSS. Your point is irrelevant. And I do not need an epitaph. You may well get there before me!!

[Paul Elliott]

Originally Posted by cappy208

Many large vessels are being required to post accurate voyage dynamic data on their AIS system. Many times the posted information is out of date or just wrong. The static data never changes, but dynamic data changes with each trip, POB, draft, destination, eta. I am unsure why the POB or eta would matter to yachters, but all the rest is pretty important. (especially if running near shoal water, or channel.)

Cappy, Class-B AIS transmits position data every 30 seconds if the speed is greater than 2kts.

Also, the static data is stuff like name, callsign, cargo, nav status (moored, underway, etc), destination, dimensions, ETA. This, especially the navstatus, is often incorrect. The dynamic data (speed, course, position, rate of turn) are almost always spot-on, since these are created by the nav electronics, not humans.

I trust the dynamic data, usually, but if I see a "moored" ship traveling at 18kts, I question their navstatus.

[chrisjs]

Since I went back to the NOAA chart to look at the TSS around Block, I did realize that I had no idea what the wavy magenta lines mean on the chart. I was unable to get the answer from the chart itself, on line from NOAA, or other sources, so thought this august body might know. I thought they might be ferry routes until I realized that some run into real shallow water. Anybody know what they represent??