Boat Plans Uk | Navigation is not precise

Boat Plans Uk

ONE OF THE THINGS that small-boat navigation teaches you is that nothing is precise. The best navigators make allowances for the unknown factors that always affect small boats, especially sailboats. They plot their positions within a circle of uncertainty and if they’re seeking landfall at a particular spot on a coastline, they aim way off to one side or the other, so they know which way to turn when they sight land.

When I was a lot younger I thought I knew how to navigate with precision. This misconception was confirmed when I sailed a 17-foot dinghy across the English Channel from Dover to Calais. I studied the tide tables and figured out the speed and direction of the tidal stream (or the set and drift as I used to call it then) for every hour. I then drew my course on the chart and adjusted the compass heading to account for the distance the tide was pushing me sideways in each hour. And thus, with a great sense of triumph, I arrived off the rather featureless French coast exactly at Calais.

It was beginner’s luck, of course. Nobody can forecast the exact speed of the current, or its exact direction. Nobody can tell you how much leeway your boat will make. Nobody can forecast your exact speed or distance covered during any one-hour period, and so the detailed markings you make so carefully on the chart turn out to be nonsense. In my case, it was probably a matter of all the errors canceling each other out — a minor miracle in other words.

Years later, when further experience had taught me some humility, I read The Yacht Navigator’s Handbook, by Norman Dahl. In the introduction he says: “When I was first taught navigation (in the Royal Navy) errors were thought of as being rather disgraceful, the sole result of poor technique by the navigator. Whilst I always accepted (and still accept today) that I was not the most brilliant navigator in the world, I was disappointed to find that, however hard I tried, errors never seemed to go away. Navigating a submerged submarine, and later, yachts of many kinds in many situations, eventually made me realize that errors are an integral part of navigation and need to be studied in their own right.”

Dahl said a major purpose of his book was to show that errors in navigation are normal and natural, and that a major skill in navigation lies in your ability to interpret the results in terms of the likely errors. He goes on to show boat navigators how they can actually use the errors to help make sensible decisions about their positions and a future course of action.

As one who had never experienced any difficulty in making errors I found Dahl’s advice very comforting, and I never again tried to do anything as impossibly precise as maintaining a rhumb line from Dover to Calais.

I expect Dahl’s book is out of print now because it was first published in 1983, before the great revolution in navigating that finally did bring near- precision to position-finding. We don’t think of errors now, because GPS doesn’t allow for that. It will tell us our position to within a boatlength in any kind of visibility, day or night.

And yet people have run aground using GPS, often because GPS is more accurate than the charts you plot your position on. There have been many reports of yachts wrecked on rocks, reefs, and islands that were where the GPS said they weren’t.

So we now all find ourselves in the position that I was in all those years ago, when I knew precisely and without doubt how to cross the English Channel. It’s surely time we started doubting again. It’s time we listened to Mr. Dahl, time we started taking all the possible errors into account. Time to accept that navigation is never precise, even with GPS.
Happy New Year
I wish you all health and happiness for the coming year. May 2016 also bring you prosperity in all meanings of the word.

Today’s Thought

The greatest of faults, I should say, is to be conscious of none.

— Carlyle, Heroes and Hero-Worship: The Hero as Prophet

Tailpiece

“What made you marry old Bella?”
“She was different from all the other girls I’ve met.”

“In what way?”
"She liked me."

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Boat Plans Nz | Idle thoughts on electricity

Boat Plans Nz

SOMETIMES I just sits and thinks. And sometimes I just sits. But on those rare occasions when I think, I think there are two major problems for the world to solve. The first is how to store electricity more efficiently. The second is how to transmit large amounts of electricity without wires.

Solving the second problem would make the first problem moot, of course, but since neither is anywhere near solution, it doesn’t really matter.

At present we hobble along by storing electricity in batteries. They aren’t very efficient. Think how often people have to charge their cell phones. They aren’t even safe. Think how many lithium-ion batteries overheat and catch fire in cell phones and Boeing 787s.

As far as transmitting electricity without wires goes, Tesla, the Great Electrician, was demonstrating 100 or more years ago that he could do it over short distances. And that is how radio works, too, of course. But what we need is a method of transmitting much larger amounts of electricity directly through space to the appliances or motors that need it, without frying up any soft-fleshed human beings who get in its way.

Imagine how the world would change if cars and trucks could drive endlessly on electric power. Better yet, imagine how it would change boats. No more smelly, heavy, complicated internal combustion engines. Think how the mammals of the sea would appreciate that.

But then, I think, if boats could use electricity to go anywhere in the world they liked, with power transmitted from satellites, or reflected by satellites, would anybody bother to sail any more?

Most small powerboats can’t carry enough fuel to cross oceans. You need a sailboat to do that. But if you could use clean quiet electricity to explore the glories of the South Seas, or cruise your own coastline, and go directly where you wanted, even if it were against the wind, why would anyone want a sailboat?

Of course, there is a glamour to sailing, a direct connection to the old days of the sailing ships and the mysteries and customs of the sea, which itself hasn’t changed in all the centuries we’ve known it.

We all know and understand that sailboats are largely impractical, but there is something about them that touches the human heart.

So when I thinks that it’s pretty certain that sooner or later mankind will invent a better battery or learn to transmit electricity, I also wonders if it will mean the days of sailboats are over, and how soon that might happen.

Today’s Thought

Indebtedness to oxygen

The chemist may repay,

But not the obligation

To electricity.

— Emily Dickinson, Poems

Tailpiece

“Angela darling, the bank has returned your check.”

“Oh, wow, that’s great. What shall we buy with it this time?”

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

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Boat Plans Canada | En route to the GPS of all trades

Boat Plans Canada

I WAS WONDERING what people might be giving their boats for Christmas when my eye fell upon an old 2008 advertisement for a Garmin Rino 530HCx. I have never seen one, but the Garmin company is famous for GPS navigation instruments and the Rino seems to be a departure from the norm.

For a start, it can’t spell its name. It should be Rhino, not Rino. It has two antennas that look vaguely like the horns of a rhinoceros. In Africa, game poachers often saw off a rhino’s horns and sell them to customers in the Far East, who grind them down into a powder that reputedly has aphrodisiacal powers.

Frankly, I’ve never understood how that works. You swallow some powder and suddenly women look attractive to you? What? Who needs rhino powder? Didn’t they always look attractive to you? But wait . . . I’m getting carried away here. Sorry. Back to the Rino:

It probably isn’t a good idea to saw off the Rino’s antennas, no matter how much of a boost your testosterone needs. I suspect something won’t work if you do that. Something on the Rino, that is.

The interesting new direction this hand-held GPS was taking was evident from its attributes as listed in the advertisement. Besides a color screen that shows where you are on a chart, there are two built-in radios. One is a Family Service Radio, a glorified walkie-talkie. The other is a General Mobile Radio Service radio, a rather more sophisticated mobile transceiver for which you need an $85 license.

In addition to GPS and two radios, the Rino has a barometric altimeter. This tells you how high you are getting, which is very useful in a season of sequential Christmas parties. There is also an electronic compass so you can find your way home if you are too high to read the GPS screen. In addition, there is a built-in weather radio that informs you what kind of storm struck you on the way home.

There’s more, but I’m sure you can see which way the new generation of electronic gadgets is headed: One GPS does it all. I can’t wait to see what they add to the next generation of GPSs, but in case any Garmin people read this column, I’d like to suggest some additions to the new “omnibus” Rino GPS.

It would be real nice, guys, if you could add a night telescope so people can find their slips after dark. And how about a few rocket flares to help the search-and-rescue people find lost sailors? A small bar would be very welcome, just a little one, of course, perhaps with miniature French maids dispensing cocktails etc., to the shivering bodies in the cockpit on the midnight watch.

I suppose it would be too much to expect a modest galley with a European chef skilled in confiture and baguettes. No matter. Most sailors I know would settle for a GPS with a fish-and-chips dispenser.

Today’s Thought

I find the sea-life an acquired taste, like that for tomatoes and olives.

— Ralph Waldo Emerson

Season’s greetings

I wish you all a merry Christmas, a happy Hanukah, and best wishes for whatever celebration you choose to observe at this time of year. I wish you peace and tranquility to calm your soul, and I wish you fortitude to face life as she presents herself in the New Year.

Tailpiece

“Good grief, what happened to your face?”

“I coughed.”

“But you don’t get your teeth knocked out if you cough.”

“You do if you cough in your friend’s wife’s wardrobe.”

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