The Offshore Voyaging Reference Site

Navigation in Fog, Part 3—Underway

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.


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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