Reversing magnetic north and south

DEEP DOWN in the southern hemisphere scientists are trying to find out when the North Pole is suddenly going to become the South Pole.

According to the British Geological Survey, a world-renowned geoscience center, “The Earth’s magnetic field has had many highs, lows, and reversals in its past. The last reversal was around 800,000 years ago. So the Earth is known to be able to re-generate its field and has done so during human pre-history.”

A report from the scientific body says that South Georgia sits within a weak spot in the Earth's magnetic field known as the “South Atlantic Anomaly” (SAA). In this area, radiation from space penetrates deeper into the atmosphere.

“The SAA is growing and spreading westwards from South Africa as the Earth’s internal magnetic field rapidly weakens in this region. Scientist believe this may be evidence of a coming reversal in the direction of the Earth’s internal magnetic field,” says the report.

Well, I knew that scientists had examined ancient rocks whose construction revealed that the magnetic field was once reversed, but I never realized it had happened several times, and I never thought it would occur again in my lifetime. Can you imagine what’s going to happen?

All our maps, charts, and  atlases will have to be redrawn with a new north at the top, a north that we call the south at the moment. Geographic globes will have to be remade upside down. You can throw away your GPS and compasses  because the sun will rise in the west and set in the east. The blue bits on bar magnets will have to be painted over with red, and vice versa.

Antarctica and the penguins will be at the North Pole and all the polar bears will have to move to the South Pole. The South Pacific will swop names with the North Atlantic. The Northwest Passage will become the Southeast Passage and the trade winds will blow northwest and southwest.

South Carolina and North Dakota will have to change to North Carolina and South Dakota. Google Earth will have to turn upside down and have all its lettering changed. And lord knows what-all else.

Gawd, what a mess. I can’t believe those secretive scientists are springing this on us at the last moment. I’m having a hard enough time coping with the concept of global warming. The idea of turning the whole world on its magnetic head is overwhelming. I think I need to lie down for a while. Either that or drink a beer. I think I’ll try the beer first.

Today’s Thought

The more science learns what life is , the more reluctant scientists are to define it.

— Leila M. Coyne, San Jose State University

Tailpiece

An Italian immigrant was having trouble with English irregular verbs.

“I can’ta weara my wool skirt anymore,” she said. “I have send it to the cleaners and they shrinked ... shrank ... shrunk ... Oh!” she broke off in desperation. “I putted on weight.”

^{(Drop by every Monday, Wednesday, Friday, for another Mainly about Boats column.)}

A navigational essential

IN MY BOOK, the fixed steering compass is the most important navigational instrument on a boat. I know that GPS has tried to steal this title ever since it was invented, but I don’t think it has earned that honor yet.

The wonderful thing about a compass is that it points the way to go, day and night and in all weathers. GPS can’t point the way to go because it only takes snapshots of where you’ve been in the past, and uses that information to tell you what your course was a few moments ago, and presumably will be in the future, if you keep going straight.

The compass is a beautifully simple piece of equipment that needs no electrical power and has hardly anything to go wrong. It does need to be lit at night, I admit, and an electric bulb is a good way to do this, but they also used small kerosene lanterns on square-riggers, before Mr. Edison came along with his new-fangled light bulb.

Oh, and sometimes, after a lot of exposure to hot sunshine, a compass will develop bubbles. In the old days, when the damping fluid was alcohol, you used to top up the compass with gin, if there was any left after the skipper had been at the bottle. Nowadays they use a petroleum-based fluid that is about 10 times as expensive, but you can get away with using odor-free, water-clear kerosene if the bubbles aren’t too big.

With compasses, as with most other things in life, you get what you pay for. If you’re buying a new one, here are two simple tests that will give you an idea of its quality:

► The test for pivot friction: Use a small magnet or a piece of ferrous metal to deflect the compass about 5 degrees to one side, then quickly remove the magnet or metal.

The compass should return to the previous position exactly. Do a similar test from the other side.

► The damping test: Deflect the compass card again, but this time let the card pivot through about 30 degrees. When it returns, see how far it overshoots the original mark. A quality compass with proper damping has minimum overshoot and will regain its original position with quick authority — that is, without excessive hunting backward and forward. A cheap compass that hunts endlessly will drive a helmsman nuts in a seaway.

Incidentally, don’t think you can cure bad deviation by installing a new compass. The new compass will have exactly the same deviation as the old one because deviation is caused by external factors on the boat around it. And if deviation is more than 5 degrees on any heading, don’t hesitate to call in a professional compass adjuster.

Today’s Thought
Change as ye list, ye winds! my heart shall be
The faithful compass that still points to thee.
— John Gay, Sweet William’s Farewell to Black-Eyed Susan

Boaters’ Rules of Thumb, #146
The wires carrying direct current from your boat’s batteries to the compass light create magnetic fields that can affect the accuracy of the compass. The rule of thumb is to twist the two wires around each other within a few feet of the compass. In this manner, the magnetic fields cancel each other out.

Tailpiece
Books I’d like to find in my library:

Mother and Child, by Polly Anderson
The Appointment, by Simeon Mundy
Ceaseless Fall, by Eileen Dover
Shattered Window, by Eva Brick
Front Row of the Stalls, by Seymour Legge
Droopy Drawers, by Lucie l’Astique

(Drop by every Monday, Wednesday, Friday, for a new Mainly about Boats column.)

Equinoctial compass check

Time to check the compass

THE CEDARS IN THE BACK YARD were twinkling with cool gray mist this morning, a sure sign that the autumnal equinox is almost upon us.

For years, when we lived on Whidbey Island, my wife June and I used to make a short pilgrimage on the date of the equinox. We went to a grassy little west-facing hillside in a quiet state park. We took along a blanket, wine, cheese and crackers, and maybe a baguette. And, of course, our hand bearing compass from the boat.

On the evening of the equinox we watched the sun go down into the sea and checked the accuracy of the compass. This is one of only two days in the year when the sun rises exactly in the east and sets exactly in west. Otherwise, it’s always either north or south of true east and west.

At that magic moment when half the blazing red sun was hidden beneath the sea horizon, I checked its bearing with the compass up to my eye. Every year, the compass proved accurate to within one degree. And at that moment I was flooded with a wonderful feeling of trust.

Cruising under sail is built on trust in so many ways. You trust that the mast won’t fall down, you trust that the engine will start, you trust that the waves in a 20-knot breeze won’t be big enough to sink your boat, and of course you trust that your compass is telling the truth.

We always stayed long after the sun sank into the Strait of Juan de Fuca. We went home cold and happy and damp from dew, and slightly woozy from the wine, holding hands, with our trust in our compass and our boat restored for another year.

And every year I think to myself what a wonderful metaphor this is for life. And I tell myself I must nurture that nascent thought and expand it into a living philosophy and write a fascinating book about it and make a lot of money and get famous and appear on Oprah. But I never do.

Today’s Thought
The west is broken into bars
Of orange, gold and gray;
Gone is the sun, come are the stars,
And night infolds the day.

— George Macdonald, Songs of Summer Nights

Boater’s Rules of Thumb, #97
Hatch dimensions. A hatch opening of 24 inches by 24 inches is adequate for most purposes, but a few inches more in either direction is always welcome. Naval architect Dave Gerr uses this rule of thumb for the minimum size of hatch in square feet needed to pass a sail through:
Racing boats: Sail area in square feet divided by 160.
Cruising boats: Sail area in square feet divided by 200.

Tailpiece
Two old salts were talking in the yacht club bar.
“When did you last make love to a woman?” one asked.
“Nineteen forty,” said the other.
“Did you say 1940?” the first asked in astonishment.
“Yeah,” said the other, “and I’m picking her up again at 2145.”

(Drop by Monday, Wednesday, Friday for a new Mainly about Boats column.)

The equinox and the compass

(Enjoy a new Mainly About Boats column here every Monday, Wednesday, and Friday.)

IT’S THE EQUINOX TODAY, one of those gorgeous, calm, sunny days that Puget Sound so often enjoys in September, and I’m thinking of a warm grassy slope on Whidbey Island.

For several years we lived on the island, which lies at the end of the 80-mile long Strait of Juan de Fuca, the restless marine highway that leads directly to the open Pacific Ocean.

Because the strait runs due west from Whidbey Island, the sun sets on the sea horizon on the days of the equinox.

So, in the early evening we would make ourselves comfortable on that warm grassy slope, with a blanket, a bottle of wine, some picnic treats, and my hand bearing compass. And we’d watch the sun.

As you know, it’s only on the day of the equinox that the sun actually sets in the true west. All summer, it’s been setting to the north of west, and all winter it will be setting to the south of west, but on the actual day of the equinox it sets plumb due west. And thus you can test the accuracy of your hand bearing compass.

Our ritual was to start watching when the sun’s lower limb kissed the sea horizon. I took its bearing with the compass when only half the flaming red disk was left showing. The bearing was never 270 degrees, of course, because of magnetic variation. The variation was about 20 degrees east in Oak Harbor at that time, and, as they teach the neophytes in navigation kindergarten, “variation east, magnetic least.” So I subtracted 20 from 270 and got 250 degrees magnetic, which, lo and behold, it always was.

And then, with renewed confidence in my little hand bearing compass, I would go sailing and point it at ships on a collision course, and use it to check the main steering compass, and take beam bearings to make sure the anchor wasn’t dragging.

I don’t live in Oak Harbor any longer, but they tell me that if you sit on that beautiful grassy slope at West Beach, the sun still goes down in exactly the same place on exactly the same date. Just plain habit, I guess.

Today’s Thought
I have a horror of sunsets, they’re so romantic, so operatic.
— Marcel Proust

Tailpiece
A little boy and girl came across a high fence surrounding a nudist colony. The girl peeked through a knothole.
“What are dey, den?” asked the boy. “Men or women?”
“Dunno,” said the little girl. “Dey hasn’t got deir clothes on.”

Honoring the hockey puck

ONE OF MY MOST VALUABLE navigation tools is the little hand-bearing (“hockey puck”)compass I wear on a cord around my neck. It’s an essential part of chart navigation, of course, because it’s what you use to take magnetic bearings of prominent features on land. Two or more of those bearings allow you to plot your position on the chart.

But the hockey puck compass is also valuable if you navigate by GPS. Let’s presume you’re heading for an anchorage on Flybutton Island, one of many in the Trousers Archipelago. As usual, with islands overlapping, covered with pine trees, and all looking alike, you can’t see any obvious entrance to Zip-Up Cove on Flybutton Island.

However, you have programmed a waypoint into your GPS; and now your GPS is telling you to steer a course of 250 degrees magnetic to Zip-Up Cove. All fine and good, but because of currents and leeway, your main steering compass is not going to take you to Zip-Up Cove while you steer 250 degrees. If you’re beating, your boat will be making leeway, so she won’t be going where she’s pointing. And if you’re in a current, as you mostly are around here, you have to allow for being set sideways.

An experienced navigator knows how to compensate for all this, naturally, and your GPS will tell you how much you’re going off course. But there’s a simple trick that’s very reassuring to Nervous Nellies: When the GPS says the direction to your destination waypoint is 250 degrees, get out your hand bearing compass and sight through it until it shows 250 degrees. Now you are looking at the actual place on land that you are aiming for. Make a note of any landmarks you can see, such as a tower or a tall tree, or a mountain with a cleft.

When you can actually see a place to aim for like this it’s a great help with the steering. You still need to compensate for being set off course, but it’s reassuring to have the GPS course confirmed by your hand bearing compass.

Another thing — if you stand in the cockpit to take your bearing, you’re usually well away from any ferrous metals and current-bearing wires, so your hockey puck compass is not affected by the ship’s deviation, and will show a true magnetic course. (If you wear glasses, just make sure the frames aren’t magnetic.)

As you probably know, there are many other uses for this little compass; too many to explore in this limited space, but they include the ability to warn you of impending collisions with other vessels, and to reveal the deviation of your main steering compass. Your hockey puck can also help you stay clear of charted (but not visible) underwater dangers, and by giving you two quick bearings, it can tell you how far you are off a prominent landmark. In addition, it will tell you in an instant if your anchor is dragging.

Furthermore, if you take it ashore with you, it will help you find your way back to the boat in a dark anchorage, or in thick fog. And so on. For 150 bucks or less, it’s a great safety aid for any sailor and a particularly valuable tool for the navigator.

Today’s Thought
Those who travel heedlessly from place to place, observing only their distance from each other, and attending only to their accommodation at the inn each night, set out fools, and will certainly remain so.
—Lord Chesterfield

Tailpiece
“Who was that eye doctor I saw you with in Alaska?”
“That was no eye doctor. That was an optical Aleutian.”
(Sorry.)

Tritium on my mind

I AM VERY good friends with my old hand bearing compass. I use it constantly when I'm out cruising. It lets me know if I'm going to hit an island, drag anchor, or run into a tug. But like most friends, it's not perfect. In fact, it worries me sometimes when I think about it.

I've had it about 12 years now. In its heyday it was Practical Sailor's overwhelming best choice in hand bearing compasses. That's because it has "deadly accuracy and long-term reliability." It also has something else that Practical Sailor didn't bother to mention. It has tritium.

Now some of you may recall that way back in the Dark Ages they had X-ray machines that you could peer into when you bought a new pair of shoes. If you wiggled your toes, your bare bones showed how much room there was in the shoes for your feet.

I don't know what alerted the shoe stores – probably people's feet falling off, I guess – but suddenly all those X-ray machines disappeared. We began to understand that it wasn't such a good thing to expose human feet to so much radiation.

Now, my compass is a far fetch from those old X-ray machines, but it does have similar properties. It uses tritium to make it glow at night. I wouldn't have known that important fact if it weren't for a flea-sized notice of the back that says: "Contains tritium H3."

My curiosity changed to alarm after I got out the dictionary -- "tritium, a radioactive isotope of hydrogen … decays by beta-particle emission and is used in thermonuclear bombs."

So now I'm very nervous when I take a bearing with my nuclear-powered compass. I don't hang about. I can take bearings with lightning speed. Every time I raise that compass to my eye, I can just feel those radioactive beta particles cruising along my optic nerve to my brain.

One day, when enough of them have gathered, there's going to be a nuclear explosion in my head. I can only hope, when that happens, that I'm standing very close to Practical Sailor's compass evaluator.

Today's Thought
We only part to meet again.
Change, as ye list, ye winds; my heart shall be
The faithful compass that still points to thee.

--John Gay, from "Sweet William's Farewell to Black-Eyed Susan."

Tailpiece
“Jeez, my wife gets historical every time we have an argument.”
“Historical? Don’t you mean hysterical?”
“No she keeps dragging up my past.”