Navigating in fog

[Neil Gordon]

>>Given what you "Know". why is there a problem with continung to sail?<<

No. The only problem is safely navigating to the next mark.

[Neil Gordon]

As mentioned before your depth sounder may provide confirmation as does navigation aides (don't bypass aides that you miss, search for them).

I'd add that you might divert to a buoy that's easier to find... maybe closer to your position even if out of your way and maybe easier to navigate to if you're following depth contours.

[Neil Gordon]

Single handed I'd get out of traffic and drop the hook.

If you can get out of traffic, you might not need to drop the hook. It is a good option (if available) to go where those lots larger can't go.

[Warren Kaplan]

One technique that I learned would apply here. Let's say you need to find an inlet to get to an anchorage. Rather than try and hit it on the nose in fog and then miss it and NOT KNOW WHICH SIDE YOU MISSED IT ON, so you don't know which way to turn to get to the inlet, do this.

Set a course to make sure you miss it on let's say the left side. When you finally get to where you can see land you then know that you must turn to starboard (or the right). You can then follow the coast until you hit the inlet and you can then turn in.

Making sure you miss to one side takes the guess work out of which way to turn in low visibility (fog or even night sailing) after you make landfall.

Its a good strategy!!

[Sea Hunt]

Neil:

I am focusing on two words in your post discussing my comments. The words are "Extra credit".

As the guy in class always voted "most likely NOT to succeed" and never getting extra credit for anything (even from the Admiral) despite some Herculean efforts, I am very proud to have finally received "extra credit" from a CDSOA member I greatly respect but have, unfortunately, never met

This calls for a celebration Guinness all around.

I hope to be on the water 04 July, weather permitting. I have thought about staying out in the bay in the evening for the fireworks. Having done this several times on commercial diving boats, it is great fun and a spectacular view. This would be my first opportunity to do so as "Captain of my own sea going vessel" The downside is the mosquitos and hoping the club's launch service is not out of operation due to liquid celebration. Time will tell.

[Neil Gordon]

Making sure you miss to one side takes the guess work out of which way to turn in low visibility (fog or even night sailing) after you make landfall.

You can use the same technique without making landfall. Let's say the depth all around is 25', including the depth of the entrance channel. Just for excitement, let's say there are huge submerged rocks guarding the entrance.

Rather than try hitting the channel, and assuming a sloping bottom otherwise, stay to the left (or right) until you hit a comfortable depth (let's say 15 feet) that you can meander right to the harbor entrance. You'll be going parallel to the rocks rather than right at them.

Check the chart carefully!

[Boyd]

The first thing to do when visibility falls is to SLOW DOWN to a speed that allows me to stop in half the distance I can see ahead. That action alone cuts the navigation problem in half. If your going fast enough in fog, rain, etc. to damage the boat in a grounding then your going too fast.

The one thing I fear about navigating in limited visibility is being run down by a big boat going fast. I always know where I am but not where the other guy is going. A collision with another small boat while going slow would be embarrasing but probably not lethal.

The radars on big boats dont find little boats very well but the channel markers do show up very strongly and you can be pretty sure they are looking for them. The one thing that the mega yacht crowd always has is the radar running, even in the marina.

While we dont have fog much in S. Fla. we do have regular squalls that cut visibility to zero. During these if I am near a marker I simply go within a few yards of the nearest one and hang out. The likely hood of a big fast moving boat hitting one of those is less.

Likewise heading for shallow water, if available and staying put there till things clear is a good way to reduce the number of boats that can run me down. At least he will run aground before running me over.

Nothing can save you from an idiot but you can cut the odds.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fla.

[Wayne Grenier]

You navigate the same way they (I) did before gps and loran-you left out one critical item-you need a compass-a chart-a clock and some means of measuring your speed (so make that 2 items)-if you leave the dock without the above items-(also include binoculars 3 items) you are not very smart-head from bouy to bouy and you will find them-right on time-right where they are supposed to be-there is a reason they are "bell bouys"-
everything is in the same location regardless of whether you can see it or not-
you should always be on a compass course even if you can see 30 miles
now currents-that's another tricky dimension-wher a gps comes in real handy-if your compass reading and your gps don't match (assuming they normally do)-you are being affected by a current-same thing with a knot meter vs the gps-
the main probelm with fog is not getting lost-its getting run over-thus you need 4 items- a radar reflector and a vhf (5 items) turned to channel 16 so you can anounce your postion course and heading and see if anyone has you on the radar and needs you to move out of the way (tugs-barges-etc.)
or a spare gps and some extra batteries will work too-
it takes practice and its very tiring and stressful and quite frankly I'd rather avoid it-even with modern instruements-

[Neil Gordon]

The one thing I fear about navigating in limited visibility is being run down by a big boat going fast.

It's even worse when it's going fast on auto pilot and the skipper is taking a nap.

By they way, as for buoys always being where they are supposed to be, always be a bit wary of floating nav aids. Sometimes they drift off. Sometimes they sink. Use them to confirm your position if they show up where they're supposed to be and I'd certainly be more wary if they didn't show up when they werer supposed to. But as a single source, be careful. (Depth confirmation can help here.)

[Bill Cochrane]

...is there a bucket of potatoes on board?

[j2sailor]

* Draw a circle of error around your current position. For instance, if you're three miles from a known mark, consider drawing a one mile radius around your current position. Lay down three course lines, one from center of circle and one tangent to each side.
* Deliberately aim for a point upwind, up current of your target with solid depth contours to follow downwind or down current to the target. Select the point 2 miles or more to the right or left of your target.
* Study the chart for depth contour curves to pass over. Be sure to correct the fathometer reading by applying tide correction and transducer depth.
* Lay courses near aids with sound devices. Remember that bells, gongs and whistle buoys require wave or wake to move the clappers or diaphragm. Electronic horns don't.
* Dead reckon based on average sailing speed. Continue to average speed every 10-15 minutes and update the DR plot.
* Estimate current set and drift by current table or observation around buoys. In a pinch, stop the boat, toss a jug with a heavily weighted line and time your drift from the object for three minutes. Estimate yardage and move the decimal two places to the left. 50 yards in three minutes is 1/2 knot. 100 yards in three minutes is 1 knot. Shoot the jug with the HB compass. The reciprocal is current set.
* If beating or reaching, estimate leeway by sighting with the HB compass dead astern through the backstay. Compare that bearing with the bearing of your upwind wake trail. On port tack, subtract the difference; on starboard tack, add the difference. Apply to your course.
* All hands in PFDs. Hoist reflectors. Sound one prolonged and two short blasts on a horn or whistle every two minutes.
* If in doubt, anchor out. Look for depths under 20 feet. Large vessels avoid shoal depths. Remember, a shoal to them may be plenty of water for you. Turn on anchor and deck lighting and ring the bell every minute along with the optional short-prolonged-short identity signal. Stagger the sound signal intervals and listen for other vessels between the signals.

[Neil Gordon]

>>Deliberately aim for a point upwind, up current of your target with solid depth contours to follow downwind or down current to the target.<<

There's a recurring theme... the safest course is not always the shortest/straightest course.

>>Study the chart for depth contour curves to pass over.<<

Back to the depth meter. It's the one "bearing" we can shoot that's accurate without visibility... the bearing is straight down and the distance off (the bottom) is acurate once adjusted for tide, etc., as you pointed out.

>>Lay courses near aids with sound devices. Remember that bells, gongs and whistle buoys require wave or wake to move the clappers or diaphragm.<<

In a calm, drive the boat in circles to make waves, then listen for the bell or gong.

>>In a pinch, stop the boat, toss a jug with a heavily weighted line and time your drift from the object for three minutes.<<

That's easy here... lots of lobster buoys.

>>If in doubt, anchor out. Look for depths under 20 feet. Large vessels avoid shoal depths.<<

That's good for heavy, deep draft vessels. I've listened to some very deep, very loud horns while in fog and was thankful that I wasn't in the major ship channel into Boston.

On the other hand, there are lots of fast, shallow draft recreational vessels around that can be trouble if you're on a course that for them could be a line from "here" to "there." I'd seek protected water but would be on the radio in addition to sounding the bell and horn.

[Bill Goldsmith]

Aside from making your own sound signals, turn off your diesel or outboard for a while and LISTEN. Listen for the sound of powerboats, tugs, ferries, loons etc. Sounds are magnified in the fog and it is good practice to do this even when all the gadgets are working, so you can guage the distance off when you hear someone else's engine or (!) bow wave.

Why loons? In the days before LORAN, RADAR, VHF, GPS and acronyms in general, downeast fishing schooners caught in pea soup would listen. Loons don't venture far offshore. If you hear the call of the loon out at sea, you are surely headed toward the coastline (and possibly rocks, etc.) When the schooner fishermen heard the loon song, they would treat it as a safety warning and head away from it, out to deeper and safer waters.

[Warren Kaplan]

As Bill mentioned, listening is also a good technique in fog. One caveat though. It is often difficult to tell from which direction sounds are coming from when socked in with fog.
However, as Bill points out in his example of schooner fisherman, just hearing the song of a loon means that shore is nearby. We would have to hope that the captain of the boat at least knows which side of his boat the coastline is on.

[The Patriot]

You're in fog with visability about the length of your boat hook. You know your position and the bearing and distance to your next mark, which is three miles away. You also know the bearing and distance to your last mark, which is two miles astern. No land in sight and none between you and the marks. No other markers. No radar. You have a good set of paper charts, VHF and a GPS whose last set of batteries just died.

What's your strategy?

Navigation and piloting in fog can be interesting, terrifying, and all shades in between. I would initially respond to Neil's question by trying to pin down the specifics of the situation. E.g., are you in a commercial traffic area, what are the wind and weather conditions, are you in a tidal flow, etc.? E.g., if you can sail in fog then you gain an enormous amount of sound info that has more than once gotten us home.

There are so many tricks that it's hard to list a specific sequence. A good starting point is an article by Roger Duncan in one of the very early (late 1970's) Practical Sailor issues in which he compares the "navigator" to the "pilot." The former uses a set of rote methods and "brute forces" the situation. The pilot, meanwhile, enjoys using the benefits of his many years of experience and wide knowledge of nature and technical issues, plus every one of his five well developed senses, to make a potentially harrowing situation into a voyage of pleasure.