Speed in Fog

The point is they didn't know all that if you read the report. The ship master stated he was confused as to the intentions of the other vessel so he effectively did nothing. Now attempting a radio contact midht not resolve that but couldn't he have tried? What did he have to lose. You here that sort of communication all the time in the Dover Straits.

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Re: wpsalm

I have radar, know how to use it and it's limitations, plus I have a decent if not 'active' radar reflector. I may not use the same weather forecasts as you though since mine don't always get it right and fog sometimes appears though not forecast.

Using your argument all the huge trucks on our roads must continue to drive at 70mph whilst all private motorists must get off the roads whenever there is thick fog.

This is not leisure versus commercial either, there have been more than a few fishing boats sent to the bottom by kamikaze ships too, one French one is believed to have been hit by a container ship and sent to the bottom with no survivors just last month in the English Channel.

Don't complain to me about the International Rules For Prevention Of Collisions, if you don't like them then campaign to have them changed. But just because there are plenty who chose to ignore them is NOT a reason to say they no longer apply.

As far as a reduction in speed is concerned, it buys some time to assess and make a course change, at 27kts (the speed of the one that sank the Moody in another post) there is very little time to pick up a small vessel, establish CPA and decide what to do, let alone do it. Indeed I doubt you would like that one coming up behind your 16kt ship in fog either with just a 2 cable CPA.






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Re: Bow doors analogy

Apparently 20 years ago the only way to run a profitable cross channel ferry service was to leave port with a gaping hole in the bow.

The nonsense you spout will eventually be exposed after another Herald of Free Enterprise type disaster.

Surely with AIS becoming mandatory it will soon be possible to fine merchant mariners with the same sort of computerised regularity offered by road speed cameras.

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If the small vessel

does not have radar (its not compulsory) and the big vessel does not sound signals. The how will the small vessel avoid the larger one?

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Re: wpsalm

If these ships are clearly not in compliance with Colregs in re not reducing speed and not making sound signals, then would this invalidate their insurance say in the case of a major collision or stranding where there could be a massive claim. I'm pretty sure it would be used as an excuse not to pay out for small boat sailors

<hr width=100% size=1>Rgds
Phil
 
Ahem!

As I pointed out in my little article in YW, Rule 6 does NOT require a REDUCTION in speed, it requires a SAFE speed.

Weasel wording, of course; those who don't like it can take it up with Professor Cockcroft.

I don't like it; in the late 1980's I issued a set of Fleet Instructions that did indeed require a reduction of speed in fog and my colleagues who actually had to stand on bridges in fog when I was in a nice air conditioned office all said I was wrong and/or was covering the company's backside. I felt that was unfair as I was ready to go into bat, and did, for anyone who reduced speed in fog - with the charterer in the case of a bulker or tanker or (far worse!) our own liner department in the case of a boxboat - and I did, We had no collisions.

Today I would not write such an instruction. Equipment is better and times have moved on. We don't expect aircraft to reduce speed in clouds.

BUT I hope I never have to cross trafficked deep water in fog in my own boat.

<hr width=100% size=1>Que scais-je?<P ID="edit"><FONT SIZE=-1>Edited by Mirelle on 20/02/2004 21:22 (server time).</FONT></P>
 
Re: Ahem!

An honest answer Mirelle if not what we want to hear.

There is a difference though with the aircraft analogy in that they have Air Traffic Control which keeps them separated from each other and small aircraft well away, even then there are many reported near misses. The pilots do not have to plot & plan collision avoidance as the Ship Master has to do. Neither is the response time similar, even a big passenger plane can turn, dive and climb quickly. Compare that to the ship stacked so high with containers the bridge officer cannot see anything close ahead, even in good visibility and which requires miles to slow to a stop, and even a course change has to be programmed in way back to be effective.

As you said though, weasel wording in truth. Until that is the apocalypse arrives (collision with a passenger ferry?) and the Sue For Miles team hits town. Who would then want to be a name at Lloyds!

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Re: AIS the last defence

It seems to me the prevailing attitude amongst professional merchant mariners is that collision avoidance gadgetry is now good enough to guard against collision with anything large enough to be a threat.

If so I think the only practical defence left for yachtsmen is the new bread of receive-only Automatic Identification System modules. Given a choice between radar or AIS+chart plotter I think I would choose AIS.

Are my expectations for AIS too high?

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Re: AIS the last defence

As I understand it from limited study, AIS will tell you where the ships are and their planned changes. Small boats though will not have AIS.

Setting aside arguments about safe speeds and so on, from a small boat point of view big ships in fog have some advantages in that they are relatively predictable and show clearly on radar. Because of their size they make few major course changes and basically travel in straight lines between TSS schemes. Small boats often show badly on radar and are much less predictable, these though will not generally have AIS. I think I will keep radar as number one defence!



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Re: AIS the last defence

> AIS will tell you where the ships are and their planned changes

Yes, every 10 seconds a big ship will send out a digital squawk via VHF containing quite a lump of data, including position, heading, length, name and rate of turn.

> Small boats though will not have AIS.

Yes and no. Rollout of the B grade AIS for small vessels is not scheduled but a company has launched a listen-only device for yachts that can plot big ship movements onto a laptop chart plotter. When coupled with the yacht's own GPS position, potential collision vectors can be plotted with, I guess, far more accuracy than is possible when software tries to do the same from radar images.

Perhaps with AIS the yacht skipper we have all been talking about recently would have had the confidence to hold his course and pass ahead of the container carrier in the channel last year.

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Re: AIS the last defence

So a useful gizmo to add to the armoury on a small boat but I suspect it would need a new plotter or a new software/chart set up for a laptop in order for it to work. So, would we rush out and buy it, for the rare (hopefully) time it would be used when radar would not be as good? I suspect this would be one which is introduced very gradually ie as a new boat is equipped or an existing one is fitted with new instruments.

I'm not sure I would want to reduce the fear factor distances for crossing ahead! Knowing the distance is one thing, there is still the fact that the wind can drop and speed with it under sail, or the prop picks up something under power.

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Re: AIS the last defence

I have also noticed this gadget. Despite owning an antediluvian boat I am not at all opposed to modern navaids!

A modest suggestion is that it could usefully be programmed to sound an alarm if a CPA of less than "x" were calculated for a vessel detected.

The problem, I think, with radar sets for yachts, including those with (M)ARPA, and with a passive AIS detector, is that someone has to act as radar observer.

On the bridge of a ship this is exactly what the OOW does; but in the cockpit of a yacht this is not practical and few yachts have a big enough crew for a second watchkeeper to be posted at the chart table watching the radar all the time.



<hr width=100% size=1>Que scais-je?
 
Re: AIS the last defence

Why wasn't small-boat AIS built into the DSC standard? It would be great if your DSC VHF (with it's existing NMEA input, and digital send/receive capability) could automatically broadcast location and heading information, as well as receive that information for input into a PC (or even a built-in CPA alarm).

Rich

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Re: AIS the last defence

Our fog routine is me at the Nav table with the radar and chart plotter and SWMBO in the cockpit. The autopilot is on (essential IMO for a steady course to give the radar plot a chance) and we have a second autopilot control at the chart table that I can use.

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Re: AIS the last defence

Indeed it is frustrating that at the moment listen-only AIS costs another £800 when most the hardware required is already present on a yacht with recent electronics.

I read through the AIS spec and all that’s needed is a VHF aerial, VHF receive on two channels, a silicon chip to translate the FM sound to digital data and then an NMEA output.

The collision prediction software can be based on O Level trigonometry.

> Why wasn't small-boat AIS built into the DSC standard?

Maybe one concern is system overload in crowded boating areas, all vessels within range have to cooperate to find a transmission slot in the 2000 per minute. Cat B AIS transmits every 30 seconds unlike the big boats that transmit every 10 secs.

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Re: Ahem! BUT

OK fair cop but
How is safe speed defined? I was taught that it's a speed which enables you to stop within half the range of visibility. Clearly, off Cap de la Hague in a thickie a ship cannot be expected to reduce speed to 1 kt so it can stop in 100 m (and that's stretching it I know), but 27 kts is way over the top and patently was not a safe speed. Can you imagine this kind of policy applying to speeding on roads in thick fog?

The thing that I find most frustrating about all this is that it's always the case that BIG is right. I just see the rights of the individual being whittled away (no refelection on your post Mirelle)

<hr width=100% size=1>Rgds
Phil
 
Re: AIS the last defence

> So, would we rush out and buy it, for the rare (hopefully) time it would be
> used when radar would not be as good?

For those fortunate enough to have a top of the range radar plus the extra software to predict collisions then AIS is not so important.

But consider a cross channel 30ft boat where fitting the dome is problematic before costs are considered.

Two years from now receive-only AIS should be way down in price to say 1/10th the cost of fitting a radar, technically it should be possible to couple this with PDA electronics. Imagine a handheld GPS that overlays ship movement vectors onto a colour chart and tells you which way a big ship is turning.

> I'm not sure I would want to reduce the fear factor distances for
> crossing ahead!

I think it was the fear factor of trying to interpret a radar image that caused a very experience yacht skipper to end up with zero boat speed under the bow of a large ship.


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