Navigation in Fog, Part 3—Underway

Fog overtakes this schooner in Maine.
Fog overtaking a schooner in Maine.

After preparing ourselves and our boat, we’re underway at last. The forecast warned of fog banks, but so far the visibility is clear and we’re enjoying the views. But we know it can’t last and we’re watching for any signs that might forewarn us that fog is on its way, such as:

  • Visible banks on the horizon.
  • Condensation forming on metal objects on deck.
  • Breath condensing.
  • Atmospheric phenomena caused by temperature inversion such as the ‘Fata Morgana’ where distant objects appear distorted, sometimes appearing in the sky upside down.
Atmospheric effects may warn of fog forming
Atmospheric effects may warn of fog forming.

Colin, European Correspondent here at AAC, is a deeply experienced offshore sailor who holds a Yachtmaster licence, and a gifted photographer and talented writer who has added a whole new dimension to Attainable Adventure Cruising. In addition, since Colin and Louise are from England and had their OVNI 435, Pèlerin built in France, they bring a European perspective to our site. You can read more about Colin and Louise and their business at their website.

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Terje M.

Thank you for a very good summary of navigation and sailing in fog. Sailing in solid fog is one of the most stressful things I can think of as a yachts captain. Been there many times, prepare for it, is one thing, doing it is something else. It always gets the blood pump going extra fast.

Thanks again,
Terje M.
Y/S Maud

Colin Speedie

Hi Terje
yes, sailing in fog can be extremely stressful, not only for the skipper….
And there’s not a lot you can do except prepare yourself practically and mentally -but that’s time and energy well spent if you know you;’re going to face it.
Best wishes
Colin

Bill Attwood

Hi Colin.
Good stuff.
A small tip from days in the military. To improve hearing at night (which works as well in fog) open mouth slightly. Sounds dumb, but it does make a difference. Obviously I don’t mean walk around in fly-catching position, but when really concentrating hard on listening.
Yours aye
Bill

Colin Speedie

Hi Bill
glad you found it useful.
Thanks for the tip – I’ll definitely give it a try! Fascinating.
I’ve seen a few people on board in fog with their mouths hanging open and never guessed they were concentrating on listening…..I thought maybe they were just worried!
Best wishes
Colin

John Harries

Hi Colin and Bill,

I don’t know, I’m thinking that at our age, (all three of us) we need to be practicing every chance we get to avoid that slack jawed old guy look—much worse problem that getting hit by a little old ship.

Marc Dacey

No, it works, and safety trumps vanity…not that anyone can spot the drooling look in fog. I believe the principle at work is that an open jaw helps the Eustachian tubes to stay clear and that’s a sort of “check valve” on the middle ear’s air pressure. Maximum hearing happens with an open mouth. Try not to moan like a zombie and you’re good.

Rob Withers

It’s not only other ships you can find by sound. In the days before GPS, we were searching for the Skellig islands off SW Ireland. The Decca (rememebr them?) we were using said we had arrived – but we could see nothing but sea and fog. However, standing at the bow allowed us to tune into the 000’s of seagulls and puffins on the island – so we followed the noise to find the island 3/4NM away

Colin Speedie

Hi Rob
I well remember fitting my first ever Decca set, a Mk.III if I remember correctly, and it wasn’t that much use at dawn or dusk, or at the limits of the chain – but it was a lot better than the old Seafix. The first time I ever sailed to the Isles of Scilly we found our way in in a similar manner. Eyeball and eardrum Mk.I – not much to go wrong is there (age apart)!
Best wishes
Colin

Paul Clayton

My friend Doug Sanderson in his book “Following the Dragon” noted that there were still a few old Newfoundland fishermen who remembered the days of sail. Doug “was amused to hear that dogs on fishing boats had a surprisingly good idea where land was, despite the fog. I suppose that might be called dps (dog positioning system)”. He didn’t say how the dogs communicated that knowledge to the fishermen, but I would not be surprised if Newfie sailors could interpret barks. I’m sure a dog would be much more acutely aware of sounds on the water than a human.

Rob Gill

Hi Paul, Rob,
Loved your comments thanks. Perhaps though, “DPS” is primarily based on smell rather than hearing, with a dog’s nose able to detect scents way better than humans. I have read that dogs may have a map of smells in their brains in the way some birds are thought to have maps with lines of magnetic flux. Also that “marking” of territories act as important datum points for this “DPS” map.
Dogs do normally have better directional hearing than humans owing I believe to the size, shape and position of their ears. But one would have to be careful, as dogs will have the same directional issues we have with noise, if one ear say is more deaf than the other.
As for interpreting signals, I recall our dog would wake up almost without fail (even from deep slumber) and start sniffing the air well outside the outer mark to the estuary where we moored – better than radar alarms! His sub-vocals like barking, growling or whimpering were sometimes easily understood, but his body language told us most. His tail, ears and how far forward he was leaning (more than once dived or fell overboard with excitement) meant we were at the closest point to “his” beach. And there was no doubting where smells were coming from, his nose was like a direction finder! As I remember it he could pick up smells even with a sea breeze (most days in summer), but perhaps not from so far away.
Polynesians navigators have long known the direction a particular species of bird will fly, to where, for any given time of day (going out to feed or home to roost for example). Rob, Puffins would be a dead give-away in northern waters during the breeding season wouldn’t they, carrying fish in their beaks?
Personally though, I think dogs are much more fun.
Rob

Colin Speedie

Hi Rob et al
dogs, eh? Who’d have thought it? Cheaper than radar, fun to have around and they even provide warmth – what’s not to like?
And yes, the Polynesian navigators were exceptional – anybody who’d like to know should search for a copy of David Lewis’ excellent book ‘We, the Navigators’.
Best wishes
Colin

Eric Klem

Hi Colin,

All good points. One which I can slightly disagree with is enjoying navigating in fog. I actually enjoy it when dead reckoning but I don’t enjoy electronic navigation. Obviously, I would not try this in a busy spot but I do it a fair amount in a sea kayak and it is really fun but I do keep a GPS close that I can turn on if I blow it. Growing up, I liked sailing in the fog and generally don’t now and wonder whether it is because I am tired of doing it or because I don’t like electronic navigation.

Regarding speed if motoring, I find that 6 knots is a great speed in many reduced visibility situations where you are not in close quarters. The reason is that it means every .1 NM takes a minute so it makes routing pretty easy.

Finally, I am actually not a fan of small boats making Securite calls in most situations. I know that it is the most conservative thing to do but if everyone does it, the radio is lit up with the calls. I really want to hear the calls of the big stuff which I want to give a wide berth but otherwise, I only like calls when there is a specific hazard. One other note on this, a lot of people read out coordinates in these calls and I don’t know anyone who plots the positions. If coordinates were really required such as in a mayday, I would still try to give a geographic position first so that someone nearby would be tempted to plot.

Eric

Pascal Cuttat

Eric,
I guess it depends a bit on where you are, but I also dislike small vessels crowding the airwaves with securite calls, especially so where it would seem useful because of dense traffic. Brief ship-to-ship communication where deemed necessary, and where available ensuring that a traffic control/monitoring station such as on the Elbe or off Rotterdam, is aware of where we are, who we are and what we intend to do is my way to go.

Cheers, Pascal

Colin Speedie

Hi Eric and Pascal
as a child I had tiny boats that I fished from off the South Devon coast and at times the fog would sock in and we’d have to find our way to shore, which we did by ear and nose, holidaymakers complaining an dogs barking on the beaches and with the smell of sun tan oil as an added beacon. But I never got to like it…..
Securite calls (like all radio calls) should be starting in the extreme, to be pulled from the ideas sack when the nerves are jangling. Out on the ocean, though, where there’s little or no traffic, they can work well, and in close quarters where there’s a lot of shipping I have the radio turned up and the cockpit speaker on – incoming calls sometimes mean us!
Best wishes
Colin

Pat Kelly

Thanks again, Colin, for these very valuable articles. Lots of “pearls” and wisdom there. When I get back home I am going to print the pages out, laminate them and keep them in my Nav Station.

Colin Speedie

Hi Pat
you’re welcome – and you must have a very big nav station!
Best wishes
Colin

Patrick Kelly

How did you know? Yes, I have a Nav station desk large enough to fully display a NOAA chart and/or a Chart book. I still use paper charts at the Nav station as well as electronic charts on the display at the helm.

Rob Gill

Hi Colin,
What a great series of articles.
A few comments on collision avoidance in “restricted visibility”. My professional experience was there is an important distinction to make between mist or torrential rain and a “pea soup” fog. In fog, to all practical purposes section II of the collision regs doesn’t apply and as you so rightly point out, vessels are jointly responsible for collision avoidance. However, in mist and heavy rain, vessels on collision course will at some point become visible to each other with time to take safe and conventional avoiding action as seemingly happened in the case of the Andrea Doria, and a number of other well documented examples. When vessels do come in sight of each other through mist or rain, the normal avoidance rules of section II suddenly apply. Thus I always believed it was best practise in these conditions to navigate using radar and sound (and now AIS) as if section II applied, anticipating the change of state under the rules when the other vessel appears out of the murk. I also believe this is why rule 19 cautions against turning to port to avoid collision, so avoiding the maritime equivalent of trying to avoid another pedestrian, both simultaneously veering to the same side, only to turn back and forth repeatedly.
So when motoring (or even under sail), for a steady bearing vessel ahead or forward of the beam on your starboard side, an early and bold alteration to starboard, putting the other vessel on your port bow will clear most situations quickly. For a vessel forward of the beam on your port side, slowing or stopping under engine, or heaving to under sail will likely be the safest move. However, if under power and forced by the actions and proximity of the other vessel to turn to port, this should best be executed as a 270 degree turn (to starboard) to provide more separation and time to access the risk of collision. Incidentally we also used this manoeuvre in good visibility if a port hand giveaway vessel was not taking action in time. I can’t think whenever there would be a case for executing a hazardous turn to port.
Avoiding action for vessels abeam or abaft the beam took more consideration and analysis of the data by radar plotting (and examination of their AIS info today) to understand the other vessel’s course, speed and intentions. In most cases slowing down or stopping will clear the danger except for an overtaking vessel near directly astern. I always believed this was the most challenging scenario, and is perhaps a time for holding one’s course, speed and nerve whilst making the appropriate sound signals. This is a time I would be on the VHF trying to make contact as soon as possible.
Most times in thick fog under power, my preferred action was always to stop and take way off, as this positive action could be communicated by the change of sound signal under the rules. There is no such distinction in sound signals for change of course when vessels are not in sight of one another.
I look forward to the next article on using radar Colin, especially as it is more than thirty years since I got my radar ticket!
Rob

Colin Speedie

Hi Rob
many good points that I agree with entirely. A couple of things I’d like to reinforce –
1. The ‘Rules’ should be hardwired into every skipper’s mind, to the extent that going against them requires a conscious decision – as in when collision avoidance has to be made at the last second. As you say, in mist, fog or heavy rain there’s usually time to take the usual actions of vessels in sight of each other. Erring from the rules when it isn’t necessary should be avoided at all costs.
2. Overtaking vessels are the worst – you’re right, in my view. In open ocean waters this is one occasion where I’ll be watching the AIS and reaching for VHF handset early!
Best wishes
Colin

Dave

Colin

A very good article. Modern electronics have changed everything. My first radar set was quite eye opening when I had a chance to see how much I was missing. Fog is not too bad as long as everybody behaves themselves. The only time I have ever been frightened is when you hear high speed power boats coming in your direction. After a couple close calls, we tend to stay at least 5 N.M. or more off shore when the fog rolls in. Even with
good viability we tend not follow rhumb lines.

Colin Speedie

Hi Dave
I agree – the first time you use radar it puts things into perspective and you realise how lucky you have been up until then.
When contemplating a passage I scour the chart for thoughts on where the greatest density of traffic will be and how to best keep us out of it. Sometimes it’s better to be offshore, others right in on the shore – it depends. But it’s a valuable first step to staying safe that only takes a moment.
Best wishes
Colin

Bill Attwood

Hi Rob.
I have a question on your comment penultimate para “There is no such distinction in sound signals……..”. Don’t the normal sound signals, “I am altering course to stbd” etc apply in this case? I may have misunderstood.
Yours aye
Bill

Rob Gill

Hi Bill, thanks for the question, the answer to which is YES and NO.
By way of explanation, I believe the important delineators in my paragraph are “in thick fog” and “when vessels are not in sight of one another”. This from Google: The international definition of fog is a visibility of less than 1 kilometre (3,300 ft); mist is a visibility of between 1 kilometre (0.62 mi) and 2 kilometers (1.2 mi) and haze from 2 kilometers (1.2 mi) to 5 kilometers (3.1 mi). And this from the collision regs: “When vessels are IN SIGHT of one another, a power-driven vessel …shall indicate that manoeuvre by the following signals on her whistle: one short blast to mean I am altering my course to starboard…” etc.

So YES, in fog with visibility of around 1000m, mist or heavy rain, the “normal sound signals” (your words) may be used once the other vessel is sighted through the gloom.

And NO in thick fog, ie. visibility under 1000m (only a bit more than two ship lengths). I never want to get that close in thick fog to another vessel IN OPEN WATER either on a ship or our yacht. Bear in mind most ships will still be going 10 knots or more, and so by the time you are this close you have both left it rather late and changing sound signals could be more confusing than helpful. Note: on a large container vessel I was on we lost all steerage at 4-5 knots! Also there may be multiple vessels around you (Murphy’s Law applies). And on many well run ships a seaman will be posted as lookout on the bow with a PTT radio, relaying sounds and sightings to the bridge (mainly for legal/insurance purposes I might add), so keeping your sound signals simple and consistent for the other vessel(s) to interpret and relay, has a lot to recommend it.
Thus in my view, all vessels are for practical purposes (in most cases, there may be exceptions), limited by the regs IN THICK FOG to the sound signals for “vessels in restricted visibility”. For a powered vessel this is either one long blast (which incidentally is T in morse with code flag T meaning “keep clear of me”) when underway, or two long blasts signalling being stopped and all way taken off (which is M in morse with flag M meaning: “my vessel is stopped and making no way through the water”).
And so to my comment that in THICK FOG (as the stand-on vessel in otherwise normal visibility), I really like stopping as an avoiding action having this second sound signal available to me, a distinction that isn’t available (for the practical purposes explained above) for change of course. Nor by the way, is this distinction available to vessels under sail in thick fog – where only raising M flag is an option, aka: “arranging the cushions, on the deckchairs of the Titanic”.
One final comment on this, an exception and “whistle code” I would be ready to use EVEN IN THICK FOG, but ONLY once another vessel was insight on collision course and not taking appropriate action, is from Rule 34 (d) of : “at least five short and rapid blasts on the whistle”. This is usually both unambiguous and demanding of attention.
Hope this better explains my comment, apologies for any confusion.
Rob

Rob Gill

I should add for clarity that my comments are directed to open water, passage making situations that I think Colin had in mind in his article. Sound signals in thick fog between vessels in restricted waters or narrow channels may be more mixed, when vessel speed and direction is better controlled and close quarter passing anticipated. Interestingly though, the sound signal for a power vessel approaching a bend or obstruction in a channel is the same as for fog, namely one long blast.
Rob

Rob Gill

Sorry should have read “any vessel approaching a bend” not “power vessel”.

Jason Timmis

Great article and guidelines Colin. Under the section of ‘Rules of the Road’ and encountering traffic within about 0.5NM I would humbly add the following comment with the obvious caveat that you said ‘think you are close’ – so we are assuming we cannot visually see anything (yet) but we have concluded there is a reasonable threat:
– Pre-visualize: (Re)Assess the waters in the area the expected encounter will occur in relation to your passage plan / current heading to determine if any course changes are prudent or would be an option. (Other than water traffic what else could I possibly need to deal with? What else should I expect to see…visually, radar, depth sounder).

Looking forward to part 4!
Regards.
Jason.

Marc Dacey

I can’t reply fully, because I’ve yet to install a new radar, but depth finders in fog in terms of following a charted 10 or even five metre contour is one of many useful tactics, and I’ve certainly made use of it as fog off the land is quite common in spring and fall around here. It’s just one more helpful data point, assuming, of course, you have a current chart and a reasonably regular contour to follow.

Colin Speedie

Hi Marc

good point and it’s one of the standard techniques taught for blind navigation for the Yachtmaster exam. And you can work from more depth if it makes you feel safer, running along the 10m contour or whatever is appropriate. Crossing contours whilst watching the chart is a good way to aid your DR, too.
Best wishes
Colin

Colin Speedie

Hi Jason
quite right. At that stage all senses must be working and flexibility and smart thinking are important. Using all electronics at your disposal, manual steering and staying alert – it’s all part of staying safe.
Best wishes
Colin

Bill Attwood

Hi Rob.
Thanks for further explanation. The views of a professional seaman have special value!
Yours aye
Bill