Normal and natural errors

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 impractical 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.[1] 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 either GPS or the charts 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.

[1] The Yacht Navigator's Handbook, by Norman Dahl (London, 1983, Ward Lock Ltd.)

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’d met.”

“In what way?”

“She liked me.”

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

Don't forget the plankton

I’M READING A BOOK about one of the most fascinating stories of survival at sea in a small boat, one that ranks right up there with Captain Bligh and Shackleton and Survive the Savage Sea.

It’s called All Brave Sailors, by J. Revell Carr (Simon & Schuster), and it deals with the sinking of an English tramp steamer, the Anglo-Saxon, after a surprise attack by a German raider ship (a powerful warship disguised as a neutral merchant freighter) during World War II.

Only seven of the Anglo-Saxon’s crew managed to escape from the sinking ship in a clinker-built 18-foot open gig. They had practically no food, just a few gallons of water, and no navigation equipment apart from a compass.

Of those seven, only two survived a 70-day sail in the gig from the eastern side of the North Atlantic to Eleuthera Island in the Bahamas, where they became instant celebrities.

They ran out of food and water fairly quickly, and a large part of the book explains how their ravaged bodies coped with the situation. What strikes me, however, is that they made no attempt to catch plankton, an act which surely would have saved more lives.

Dr. Alain Bombard demonstrated the abundance of life-giving plankton in his Atlantic crossing in his raft, L’Heretique. Before that,  William Beebe, the famous naturalist, writer, and explorer, undertook the laborious task of counting the number of the tiny creatures he caught in a net. Here’s his account, from The Arcturus Adventure (G. P. Putnam’s Sons):

“One dark moonless evening I put out a silk surface net, the mouth of which was round and about a yard in diameter. At the farther end of the net a quart preserve jar was tied to receive and hold any small creatures which might be caught as the net was drawn slowly along the surface of the water. This was done at the speed of two knots and kept up for the duration of one hour.

“When drawn in, the net sagged heavily and we poured out an overflowing mass of rich pink jelly into a flat white tray."   

Most of the these individuals were primitive crustaceans, which make plankton a rich, nourishing food, even raw.

It’s also worthwhile repeating that all these creatures that we call plankton were caught at the surface on a dark night. Beebe repeated the experiment in full daylight and caught only about 1,000 individuals instead of 40,000,000.

“Plankton will have nothing of the sun or even of moonlight,” he observed, “and remains well below the reach of the stronger rays.”

You might want to try dragging a net, or even a shirt sleeve knotted at the end, next time you’re at sea on a dark night. You never know when this knowledge might come in useful.

Today’s Thought

Shipwrecked men in an open boat, if their lot is cast on waters rich in plankton, never need to starve to death if they can manage to drag an old shirt, net, fashion, through the water at night. — William Beebe, The Arcturus Adventure

Tailpiece

“How’s your son getting on these days?”

“He just turned 16. He kissed his first girl and started smoking.”

“Wow! Must have been some kiss.”

Noah and an ark of reeds

I DON’T RECALL having heard anything said about plants on Noah’s Ark. Animals, yes, two of every kind, but no flowers or trees or vegetables. Noah certainly had sufficient meat on board for a circumnavigation but he would have found it hard going without barley for his beer and rice for his breakfast crispies.

I like to think of him as one of the first yachtsmen in the business, but perhaps he was more like Thor Heyerdahl than Joshua Slocum, because, contrary to what most of us were taught in Sunday school, Noah didn’t build his ark of wood. At least, not according to The Oxford Companion to Ships and the Sea he didn’t.

The OxCom says that the ark, in which Noah and his family escaped the deluge with all the animals, was probably not built of wood because there simply wasn’t enough wood in the entire Tigris-Euphrates region to build it of timber.

You will recall, of course, that the ark measured 300 cubits in length by 50 in beam and 30 in height. In terms of Egyptian royal cubits of about 21 inches each, that translates to a vessel measuring 521 feet long by 87 feet wide by 52 feet high. More of a ship than a boat, actually.

This has led researchers to assume that the ark was therefore built, according to the local traditional fashion, of papyrus reeds, roughly in the shape of a tea tray, with a little local wood used in the domestic quarters, cowsheds, pigsties, and so on. It sounds an awful lot like a larger version of Heyerdahl’s Kon Tiki raft.

Of course, one has to ponder how a 500-foot-long vessel constructed of reeds would hold together in any kind of seaway, but it is not for us to wonder why. Noah had faith, which is apparently as useful as a good solid wooden keel, and is not to be questioned.

Today’s Thought

God’s revelation to Adam didn’t instruct Noah how to build the ark.

— Ezra Taft Benson

Tailpiece

A little girl had just finished her first week of school.

'I'm just wasting my time,' she said to her mother. 'I can't read, I can't write, and they won't let me talk!'

Thinking about boat presents

I’M OF THE OPINION that you can never prepare too far ahead for Christmas. Furthermore, I have heard it said by both sexes that it’s very difficult to buy Christmas presents for men. That being the case, perhaps we men should do our bit to make this task easier, and, incidentally, thereby help the economy along.

One way to do this would be to make up a list of the Christmas presents we’d like to receive, and hand it out to friends, relatives, co-workers, and passers-by. Some of you will think this is a very crass thing to do, but it has occurred to me that a wish-list of this sort would be completely acceptable if it were presented in the form of a request for items for your boat.

You might think this a little strange at first, but it’s not really. It moves the guilt factor away from you to a third party. And people (even landlubbers) know instinctively that boats have souls. They realize that there are strong emotional ties between sailors and their boats that stop short only of kissing and hugging. Well, in most cases, anyway.

Now, you may be saying, “But people will surely query why a boat would need a new flat-screen, Internet-ready, 72-inch, plasma TV with icemaker.  Or a case of Johnny Walker Red Label whisky; or a five-year subscription to Playboy. How do you answer them?”

Well, use your common sense. Close your eyes slightly. Look wise and mysterious. Say: “There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.” Explain that the bond between a man and his boat is intimate and very private. Tell them you have this intuitive, exclusive insight into your boat’s true needs and desires.

And make sure they realize that every boat knows the difference between real Johnny Walker and the cheap hooch they distill up in those scruffy hills in Arkansas.

Today’s Thought

Ever since Eve gave Adam the apple, there has been a misunderstanding between the sexes about gifts

— Nan Robertson

Tailpiece

He asked her for a burning kiss;

She said in accents cruel:

“I may be called a red-hot babe

“But I’m still nobody’s fuel.”

Propellers made easy

A WHILE BACK I was editing an article for Good Old Boat magazine. It said:

 “When you select a propeller, you should match every dimension of that propeller to the hull and the engine driving it to attain maximum efficiency. This makes propeller selection and calculation very difficult for those of us who are not naval architects.”

Well, that’s not completely true in my opinion. The experts in too many fields, such as navigation and splicing rope, like to spread the word that it’s more complicated than it really is.

There are two ways of selecting a propeller: theory and practice. And even naval architects have to resort to trial-and-error after they’ve tried their best with theory.

Let’s say you’re not satisfied with your boat’s performance under power, and you suspect the propeller is the wrong size. First check the diameter. Go to page 45 of my book, The Boatowner’s Handbook, where there’s a handy little graph. Lay a ruler between horsepower and prop-shaft revolutions, and see where it crosses the column marked “Propeller diameter.”

On page 47 you’ll find another graph that shows you the pitch you need. This points you in the right direction for your prop. It’s about as good a result as the naval architect will get with all his complicated calculations.

So much for theory. Now we come to the practice. This doesn’t hardly need any brains at all, so it suits me fine.
Make sure your boat’s propeller is free of barnacles and the hull is reasonably clean. Take her for a run in calm weather. The ideal propeller will allow the engine to reach the manufacturer’s top-rated revolutions per minute (and therefore full power) with the throttle opened fully. And at this stage, your boat should be achieving full hull speed.

Now, if your engine starts to lug, or emit black diesel smoke, before it reaches top-rated rpm, you’ve probably got too much pitch. It’s like trying to ride a bike uphill in top gear.
On the other hand, if your engine reaches top revs too easily — that is, before your boat reaches hull speed — you probably need to increase the pitch. You’re riding downhill in low gear and your little legs are whizzing around but you’re not going very fast.

A propeller shop can alter the pitch of most auxiliary sailboat props a couple of inches at a fraction of the cost of a new propeller. For auxiliary sailboats with the usual 2-to-1 reduction gearbox, a decrease in prop pitch of 2 inches will increase engine revs per minute by about 300 to 400.
It’s unlikely that you’ll need to change the prop diameter, but you might like to know that for roughly equivalent performance, if you decrease the diameter 1 inch, you should increase the pitch 2 inches.

You don’t need to be a naval architect to check your propeller’s actual performance this way. It’s as much art as science — plus a bit of grunt work to get the damn prop off the shaft to which it clings so determinedly.

Today’s Thought

An expert is somebody who is more than 50 miles from home, has no responsibility for implementing the advice he gives, and shows slides.

— Edwin Meese 3rd, White House counsel

Tailpiece

A pessimist is a person who builds a castle in the air and then locks himself in the dungeon.
An optimist, on the other hand, is a person who fixes your eyes.

Racer/cruisers and vice versa

I WAS THINKING the other day that I need another little Santana 22 sloop.  I owned one about 20 years ago. I turned her into a miniature “sport cruiser” and loved her to bits. She was the first successful  design from the board of Gary Mull, one of my favorite sailboat designers. About 800 Santana 22s were built by the Schock company in California in the late 1960s and early 70s. You’d think there would be at least one still around here in reasonable condition, but if there is, I can’t find it in this neck of the woods.

Mull was one who had very definite ideas about the difference between cruiser/racers and racer/cruisers. He didn’t design either. He simply created what he called “good sailboats.”

He was quoted as saying:  “If you call one a club racer, what you are really saying is that it is a racing boat that isn’t quite good enough to race against the real racing boats. It can only do club racing.

“If you call it a cruiser/racer, that’s some sort of hermaphrodite that is neither fish nor fowl, but is probably slower than a racer/cruiser, which is also a hermaphrodite but maybe looks racier than its cruiser/racer cousin.”

Whatever other people called his designs, it didn’t matter to him. Here is what he strove for in all his boats:

* Good looks and performance. “It has to be good-looking and it has to sail well.”

* Good balance.

* An airy, bright, pleasant interior. (“So you don’t feel like you’re going to jail when you go down below.”)

* A comfortable cockpit. (“Where you can work the boat without bashing your elbows or tripping over or whatever.”)

As for cruiser/racers and racer/cruisers, his philosophy was simple: “If you want to cruise for a while, you can do it by simply loading aboard the stores and some clothes, and just do it. If you want to race it, you can do that by off-loading some of the stores and gear and going racing.

A “good sailboat” like this wouldn’t be a successful racer under the International Offshore Rule “because it’s not an IOR boat,” said Mull. “But it’s probably going to be a better cruising boat than 99 percent of the cruising boats on the market, which are caricatures of cruising boats.”

Strong words from a strong character who was one of America’s most talented designers.

Today’s Thought

To me, the drawn language is a very revealing language; one can see in a few lines whether a man is really an architect.

— Eero Saarinen, NY Times, 5 Jun 77

Tailpiece

Rumor has it that the Feds are going to replace the dollar bill with a metal coin.

It’s called the quarter.

Squeezing in berths and heads

A READER called Eric asks: “Why do boat builders insist on putting TWO toilets/heads in a boat as small as 32 feet? C'mon, how many 400-square-foot apartments/houses on land have two bathrooms?”

Well, Eric, if I had to take a flying guess I’d say it was the boatbuilder’s sales department that demanded two heads. Apparently it’s a major selling point, especially among the fairer sex. It’s the same reason that builders insist on putting six berths in a four-berth boat, and four berths in a two-berth boat. The sales manager wants to be able to boast that his 25-footer is a family boat that can accommodate Mom, Pop, and four kids on weekend jaunts, unlike the competition whose 26-footer only has berths for two adults and two kids.

It sounds better in the ads, and looks good in the color brochure, but no boat designer in his right mind would come up with this idea on his own. He knows better than anyone how awkward and inconvenient too many berths are in a small boat, and what a wicked waste of space. He also knows how little time people spend in the head and how hard it is to compensate for the extra space a second head steals from the interior.

But he has to earn an honest nickel, and the boatbuilder is the boss, so he grinds his teeth and squeezes in a couple of berths here and a couple of heads there, knowing full well that he’s creating a travesty of boat design.

There are a few traditional designs that follow more normal rules of practical and esthetic design and, ironically, they usually cost a lot more than the plastic Best Westerns that fill our marinas.

So, Eric, I’m afraid there’s only one thing left to do, and that’s to take yourself to an old-fashioned naval architect and commission him or her to design you a boat with as few bunks and heads as you consider appropriate. You will instantly become that architect’s dream customer, and you might even feel your feet being kissed, but whether you’ll be able to find a builder willing to create this aberrant kind of boat, one so far removed from the modern norm, is quite another matter.

Today’s Thought

Change doth unknit the tranquil strength of men.

— Matthew Arnold, A Question 

Tailpiece

“Did you visit that spiritualist last night?”

“Yeah.”

“Was she a good one?”

“No, just a medium.”