YM fog ?

[jordanbasset]

The premise of the article was unexpectedly getting caught of in fog. So not a choice.
A good point though setting out knowing thier is fog at the time or in the forecast.
It’s a good question would you set out in fog?

We were in Povoa de Varzim and it was the fog horn that made the decision for us.
We were there for 5 days and the fog never seemed to lift and the fog horn, which was an air raid siren type, never stopped. It was like mental torture, almost impossible to sleep. In the end we left in fog, we had radar, about 3 miles off shore it was completely clear.

 

[RupertW]

Far from a no brainer.

Thinking about unclipping when you're busy getting past the rabbit in headlights moment, then trying to avoid a collision may not happen and if the boat starts pulling me down, I don't rate my chances of unclipping. My risk assessment - which may change from moment to moment, is to clip on if my risk of going over the side is greater than the risk of collision, which probably means anything out of the cockpit, and unclip if the risk of collision is greater than the risk of going over the side, which is probably safely in the cockpit in reasonable conditions.

Just to add another ingredient, should one remove one's lifejacket when going below to make a cuppa, or whatever? This doesn't only apply in fog.

Someone at our club was saying that if the cabin fills with water and your jacket inflates, it's likely to trap you below. He's not wrong, but while I'm fairly safety conscious, I don't. Maybe I should but, on balance, it's such a faff that having a knife easily to hand so I can stab it in extremis seems to me to be a reasonable alternative.

Absolutely right - it's only a no brainer to clip at night, in bad weather and in fog if the definition of no brainer is not to use your brain to assess risk but instead to follow your own rules blindly.

Fog changes the risk markedly to add in a far higher (but still low) relative risk of boat going down after a collision. So you may still decide that the very low but real risk of going overboard is still higher than the new risk of collision or you may decide the new circumstances need a change of action - and unclip. Both views are valid and depend on crew capability, thickness of fog, whether in s busy shipping area or not and so on.But just carrying on in a fixed mindset regardless of the current situation is a scary form of self-therapy not looking after yourself and crew.

 

[Kukri]

I can only base my view on lots of sailing in fog and practising it hundreds of times. But really just like at night and in poor weather including whiteout rain if someone goes over not clipped on its goodnight irene.
To unclip takes a part of a second.
No brainer.

I certainly agree. In fact the advice to unclip in fog reminds me of the advice - once found in every seamanship manual - to arrange an endless whip to a sea anchor so as to haul oil bags out to it. There was just one problem with this - a conventional drogue, under load,, attached to a conventional three strand hawser, spins like a top. Anyone who has watched one knows that. So the advice was born of over thinking the problem, ashore, by people with no practical experience of deploying a drogue at sea. None the less the advice went down from book to book.

I suspect that the advice to unclip in a fog is in the same category of over thinking the problem. The advice to take off your LJ when going below is certainly in that class - no cabin ever flooded instantaneously.

(This assumes that the tether can be unclipped at the harness/LJ end. I have seen tethers that cannot be, because they are larks headed onto the harness. I don't like them.)

I don't like using my brain to assess risk. If I am cold wet tired and a bit seasick, my brain isn't at its best. I prefer to use a different approach, with a combination of training to the point where actions become automatic and the use of visual clues to remind me of things. For example, if I unclip my tether at the harness end and leave it lying in the companionway when I go below, the sight of it reminds me to re-attach it as I go on deck.

 

[johnalison]

I have set out in fog quite a few times, with and without radar. On one occasion we took the part of lead boat leaving Brightlingsea by virtue of the fact that we had Decca. A mixture of local knowledge and the echosounder got us all back into the Blackwater where the fog lifted. On other occasions we have left in summer fog from ports such as Fecamp or Dieppe with the horns sounding knowing that there was little shipping on our passage and that either the fog would lift or my radar would make it safe. the only time we were reckless about it was our first Continental crossing, from Ramsgate to Calais with about eight club boats. We agreed the route and that we would all turn back if we encountered fog but when we rounded the Goodwins and met fog our determination overcame our caution, and having no VHF at the time ploughed on, pooping off our horns and out of sight of each other. My navigation consisted of making 10 degrees alteration to starboard if I heard a hovercraft that side, or ten degrees the other way if it was to port.

There are circumstances when it is reasonable to set out in fog. What can often be more hazardous is to set out when fog is expected later, often over an extensive area in open water with shipping.

 

[Poignard]

It's difficult to decide what's best regarding clipping on.

If a ship hits you a glancing blow, knocks you violently on your beam ends but without smashing the hull, and you are thrown out of the cockpit, you will regret not being clipped on.

On the other hand, if it smashes your hull so badly that your boat sinks, you will regret being clipped on.

In the situation I described in my previous post [#13], we decided not to clip on. Fortunately, we did not have to put our decision to the test!

 

[oldmanofthehills]

Given the price and it availability of equipment it is foolish for any vessel to set off without AIS and preferably a transceiver.

A class B transponder costs over £2000 and I certainly cant afford that, and neither can most leisure sailors. Perhaps if I was rich enough to own a 35ft boat and live near Chichester I could afford it and perhaps if I was dealing with cross channel or solent traffic I might think it more desirable.

I have sailed into fog in the Bristol channel - where as you might know turning back is often not physically possible due to tides -and have simply kept out of main shipping lane and used Mk1 ear and Mk1 mouth operated horn and had a nice sail without no great fear of sudden demise, and all this before chart plotters and GPS. Obviously now my new radio has AIS receiver it would be easier to spot the big boys but I managed for years without.

 

[dom]

A class B transponder costs over £2000 and I certainly cant afford that, and neither can most leisure sailors....

Just as well you can buy a Clas B transponder for <£500 then

 

[awol]

[pedantry] A "transponder" is a device for receiving a radio signal and automatically transmitting a different signal. A "transceiver" is a device that can receive and transmit.{/pedantry]

An AIS transceiver can be had for less than £300.

 

[Roberto]

I have the impression that if a collision is violent enough to cause an immediate sinking without allowing two seconds to unclip, the shock would be so severe as to not leave any living being onboard (or in the water, for that matter).

 

[Kukri]

I have the impression that if a collision is violent enough to cause an immediate sinking without allowing two seconds to unclip, the shock would be so severe as to not leave any living being onboard (or in the water, for that matter).

Exactly.

We might also note that a tanker or a bulk carrier has a round bow, and with today's fuel prices and freight rates, she is probably going to be making between ten and twelve knots, so a yacht is quite likely to be shoved aside by the bow wave and to scrape down the hull unless she is unlucky enough to get her mast and rigging tangled in an anchor . Older container ships, designed for double that speed but probably making thirteen, have hatchet shaped bows and won't throw a yacht aside.

 

[johnalison]

[pedantry] A "transponder" is a device for receiving a radio signal and automatically transmitting a different signal. A "transceiver" is a device that can receive and transmit.{/pedantry]

An AIS transceiver can be had for less than £300.

I have no doubt that you are right but, like many linguistic battles, this one has been lost a long time ago. I'm afraid that I will be one of those people who will persist in saying 'transponder' simply because it is easier to say than 'transceiver'.

 

[dom]

I have no doubt that you are right but, like many linguistic battles, this one has been lost a long time ago. I'm afraid that I will be one of those people who will persist in saying 'transponder' simply because it is easier to say than 'transceiver'.

Trouble is, almost all of the equipment manufacturers use the term these days

 

[lw395]

[pedantry] A "transponder" is a device for receiving a radio signal and automatically transmitting a different signal. A "transceiver" is a device that can receive and transmit.{/pedantry]

An AIS transceiver can be had for less than £300.

An AIS set is a transponder.
The A stands for automatic.
Your AIS transmits in response to the network (of which it becomes a part). You cannot autonomously transmit with your AIS. It's not really a transceiver in any useful or conventional sense.

 

[awol]

An AIS set is a transponder.
The A stands for automatic.
Your AIS transmits in response to the network (of which it becomes a part). You cannot autonomously transmit with your AIS. It's not really a transceiver in any useful or conventional sense.

I bow to your obviously superior knowledge. Perhaps you could send a correction to Wikipedia who, like me, thinks otherwise.

Basic overview. AIS transceivers automatically broadcast information, such as their position, speed, and navigational status, at regular intervals via a VHF transmitter built into the transceiver. ... The signals are received by AIS transceivers fitted on other ships or on land based systems, such as VTS systems.

You could also disabuse the NMEA

How does AIS work?
The heart of the system is a transmission protocol called Self Organizing Time Division Multiple Access (SOTDMA).
This protocol is what allows AIS to be autonomous and continuously operational.

 

[RichardS]

An AIS set is a transponder.
The A stands for automatic.
Your AIS transmits in response to the network (of which it becomes a part). You cannot autonomously transmit with your AIS. It's not really a transceiver in any useful or conventional sense.

The A does indeed stand for Automatic but that's not the defining feature of an AIS transceiver.

Richard

 

[Leighb]

Those who said that a yacht cabin would not be instantly flooded in a collision with a ship should read MAIB report of the collision between yacht Orca and the dredger Shoreway. https://assets.digital.cabinet-office.gov.uk/media/555b29fde5274a74ca000007/MAIBInvReport10_2015.pdf
This was in daylight not fog, but the skipper wearing his life jacket would have been trapped below if it had inflated, luckily for him it failed. His wife who was washed into the cabin through the companionway sadly drowned, but even if she had remained above deck she would still have drowned had she been clipped on.

 

[Kukri]

Fair point. Thank you.

 

[lw395]

I bow to your obviously superior knowledge. Perhaps you could send a correction to Wikipedia who, like me, thinks otherwise.

You could also disabuse the NMEA

From Wikipedia, as you seem to think that's an authority:
"The automatic identification system (AIS) is an automatic tracking system that uses transponders on ships and is used by vessel traffic services (VTS). When satellites are used to detect AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport."

The IMO use 'Transponder' a lot, I think they have a bit of authority?
http://www.imo.org/en/ourwork/safety/navigation/pages/ais.aspx

Personally I think either term is OK, because they both meet the need of differentiating from AIS receive-only units.
Neither properly captures what an AIS ship node actually does.
It's not really a Transceiver, because it doesn't have the function of transmitting data from the ship. The data it transmits is essentially a response to what it receives from GPS. There's generally not a continuous data input.
It's not really a transponder because a large part of its function is to receive data fom elsewhere and process it for use at the ship. There is a continuous data output. It has a significant function of providing info to the ship carrying, in order to avoid collision.

 

[Frank Holden]

From Wikipedia, as you seem to think that's an authority:
"The automatic identification system (AIS) is an automatic tracking system that uses transponders on ships and is used by vessel traffic services (VTS). When satellites are used to detect AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport."

The IMO use 'Transponder' a lot, I think they have a bit of authority?
http://www.imo.org/en/ourwork/safety/navigation/pages/ais.aspx

Personally I think either term is OK, because they both meet the need of differentiating from AIS receive-only units.
Neither properly captures what an AIS ship node actually does.
It's not really a Transceiver, because it doesn't have the function of transmitting data from the ship. The data it transmits is essentially a response to what it receives from GPS. There's generally not a continuous data input.
It's not really a transponder because a large part of its function is to receive data fom elsewhere and process it for use at the ship. There is a continuous data output. It has a significant function of providing info to the ship carrying, in order to avoid collision.

Hmmmmm.... mine transmits information ( automatically ... all the time... not just when 'polled' ) ... both GPS information and also info that I have entered into it... class of ship, flag, MMSI, length and breadth.... so it is a transmitter...

It also receives information all the time ( lets not get pedantic about the meaning of 'all the time' ) therefore it is a receiver.

As a result I call mine a transceiver...

At some level beyond my knowledge set they can also function as a transponder...
Case in point...... we crossed the line on the chart defining harbour limits when entering the well known yachting mecca of Mejillones. Our AIS promptly displayed a message welcoming us to the port.... so their transceiver had responded to our signal.... not simply received and displayed our info... thus they had an AIS transponder.

Edited bit.... Class A doesn't just transmit GPS and static info like a Class B .... also includes dynamic ship based info... eg ship's head, rate of turn, and log speed.

 

[RichardS]

An AIS set is a transponder.

It's not really a transponder .......

Richard