The evolution of steering

WHAT WOULD YOU SAY is the most unappreciated part of a sailboat, the one thing that’s invariably overlooked and neglected, but without which the boat simply cannot function? Yes, that’s right, it’s not the skipper. It’s the rudder.

On larger boats it’s out of sight (apart from the few stern-hung rudders still around) and it’s largely out of mind. It’s a truly modest and uncomplaining piece of equipment, one that doesn’t need to be fed constantly with expensive diesel fuel, one that never goes flat and needs charging, one that never has to be taken to the sewage pump-out every week, or varnished every six months.

It is a marvel of efficiency; and also such a marvel of simplicity that you have to wonder why it took so many hundreds of years to make an appearance on sea-going ships.

The ancient Phoenicians, the Romans, and even the Vikings, used steering boards — oars or paddles, usually hung from the right-hand quarter. (Hence the starboard — steerboard — side. The other side was the side that rested against the port, so the steerboard wouldn’t be damaged.)

It wasn’t until 1242 A.D. that pictorial evidence appeared of a centerline rudder on a ship in Europe. It was, if you’ll forgive me, a turning point in marine design. Apparently this new-fangled invention was received with such enthusiasm that it was quickly adopted by shipbuilders all over the world. Pintles and gudgeons suddenly became household words.

How does the rudder work? Well, in the crudest of terms, if you push it to one side, the water flowing past strikes that side with more force than it strikes the other, so the rudder tends to be pushed sideways, taking the stern with it. (It is actually a foil whose shape provides “lift” like an airplane wing does, but never mind that for the moment.)

I often marvel at the way a tiny rudder can turn a 250,000-ton oil tanker; although, lurking in the back of my mind somewhere is something vague I once read about the rudder only initiating the turn, and the ship’s hull itself acting to reinforce the turning moment, as might a wedge driven through the water.

It’s interesting to note that the average sailboat rudder will stall and lose efficiency if it is put over more than 35 degrees from dead ahead. In fact, it will act as a good brake if you are approaching a dock too fast and you can put it over to 90 degrees, first one side and then the other.

While most rudders lurk quietly and invisibly beneath their mother ships, the importance of their roles has not been lost on naval architects, physicists, and engineers. The design and performance of rudders is the subject of countless scientific papers and even whole books. In this respect, if you should wish to develop your latent rudder fetish, get hold of a book called The Development of the Rudder, by Lawrence V. Mott. It’s a fascinating and lavishly illustrated volume of nautical archaeology that digs deep into the conception of the modern rudder, starting with its crude but rather interesting parents in various parts of the world.

Even if you don’t find yourself entirely enthralled by rudders, it will help while away large parts of the long, bleak period between the morning cocktail and the evening sundowner.

Today’s Thought

The ancient sailor said this to Neptune in a great storm, “O God, thou shalt save me if thou please, if not, thou shalt lose me; yet will I keep my rudder true.”

— Montaigne, Essays

Tailpiece

“And you, madam, what’s your husband’s average income?”

“Oh, usually well after midnight.”

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

Tricky question from lame brain

MY BRAIN HAD A QUESTION for me in the middle of the night: How does a rudder rud?

“We know how a writer writes and how a singer sings,” it said, “but how does a rudder rud?”

My brain thinks it’s quite funny on the quiet but in fact its sense of humor is quite warped. Nevertheless, as I had the rest of the disturbed night to think about it, I did start considering the question.

I seem to remember learning that it’s not the rudder alone that steers a sailboat. It’s all very vague now, but apparently the rudder just starts the boat turning, and the hull, now being at an oblique angle to the boat’s forward progress, is forced off to one side or the other. So I’m not exactly sure how the rudder ruds, except that it’s a hydrofoil that generates lift in either direction, according to how you turn it.

Nevertheless, it’s the action of the rudder that you feel when you’re slicing along to windward on a lovely day in a calm sea and all is wonderful around you. A couple of fingers on the tiller is all that’s need to keep your little beauty running straight and true — until a sudden gust of wind comes along, and you find yourself tugging the tiller up under your chin. It’s the dreaded weather helm, of course. Even on boats where the sail plan is nicely balanced with the keel plan, weather helm will show its ugly face, and it’s not hard to see why.

If you take a model yacht, place it in water (your bath will do), and use a finger behind the mast to push it forward, the boat will tend to go straight as long as the mast is upright. But if you heel the yacht over and push in the same place in the same direction with the same finger, you’ll find that your finger, the source of forward power, is now out to the side of the boat. You’re creating an off-balance push from one side of the boat. Naturally, the boat will try to turn toward the opposite side. You will have to counteract that tendency to round up into the wind by turning the rudder.

Now the rudder is a very effective brake. On sailboats it needs to be a large hydrofoil because it moves through the water comparatively slowly. Various designs of rudder make brakes of greater or lesser efficiency, but they all slow the boat down, some considerably, when they are turned. That is why it pays to reef the sails when the boat is heeling too much. The mast, being more upright now, creates less weather helm for the rudder to deal with.

This is all very simplistic, of course, suitable for a lower-class brain to absorb. It’s presuming that the driving force is transmitted at one point through the mast, which is convenient but not true. You can tell that because of how the mainsheet pulls when you’re on the run. There are forces on the shrouds and stays, too, all driving the boat forward.

It’s also presuming that the rudder is working upright in optimum conditions in calm water, which is not always the case. We all know that a rudder is less effective the more the boat heels, and hardly works at all in the foaming water left by a wave breaking under the stern. So it’s all really highly complicated and, I regret to say, too esoteric for a brain like mine.

Today’s Thought

He who will not be ruled by the rudder, must be ruled by the rock.

— Isaac D’Israeli, Curiosities of Literature

Tailpiece

Words of wisdom from Scotland:

“A weel-bred dog gaes oot when he sees them preparing tae kick him oot.”

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

A noteworthy turning point

WHAT WOULD YOU SAY is the most unappreciated part of a sailboat, the one that’s invariably overlooked and neglected, but without which the boat simply cannot function? Yes, that’s right, it’s the rudder.

It’s out of sight (apart from the few stern-hung rudders still around) and it’s largely out of mind. It’s a truly modest and uncomplaining piece of equipment, one that doesn’t need to be fed constantly with expensive diesel fuel, one that never goes flat and needs charging, one that never has to be taken to the sewage pump-out every week, or varnished every six months.

It is a marvel of efficiency; and also a marvel of such simplicity that you have to wonder why it took so many hundreds of years to make an appearance on sea-going ships.

The ancient Phoenicians, the Romans, and even the Vikings, used steering boards — oars or paddles, usually hung from the right-hand quarter. (Hence the starboard -- steerboard -- side. The other side was the side that rested against the port, so the steerboard wouldn’t be damaged.)

It wasn’t until 1242 A.D. that pictorial evidence appeared of a centerline rudder on a ship in Europe. It was, if you’ll forgive me, a turning point in marine design. Apparently this new-fangled invention was received with such enthusiasm that it was quickly adopted by shipbuilders all over the world. Pintles and gudgeons suddenly became household words.

How does the rudder work? Well, in the crudest of terms, if you push it to one side, the water flowing past strikes that side with more force than it strikes the other, so the rudder tends to be pushed sideways, taking the stern with it.

I often marvel at the way a tiny rudder can turn a 250,000-ton oil tanker; although, lurking in the back of my mind somewhere is something vague I once read about the rudder only initiating the turn, and the ship’s hull itself acting to reinforce the turning moment, as might a wedge driven through the water.

While most rudders lurk quietly and invisibly beneath their mother ships, the importance of their roles has not been lost on naval architects, physicists, and engineers. The design and performance of rudders is the subject of countless scientific papers and even whole books. In this respect, if you should wish to develop your latent rudder fetish, get hold of a book called The Development of the Rudder, by Lawrence V. Mott. It’s a fascinating and lavishly illustrated volume of nautical archaeology that digs deep into the conception of the modern rudder, starting with its crude but rather interesting parents in various parts of the world.

Even if you don’t find yourself entirely enthralled by rudders, it will help while away large parts of the cold and soggy winter we’re expecting around here, thanks to La blasted Niña.

Red faces over snakes
THERE was some editorial embarrassment at the Walnut Street Gazeout (should be Gazette) this week. You’ll recall that an inmate was asking for help in finding a book called The Tactics of Small Boa Tracing.

Well, it turns out that either his handwriting was illegible, or his contact down the row doesn’t read too well. The book in question is actually The Tactics of Small Boat Racing, by Stuart H. Walker, MD. It’s still available, and any decent bookstore can order it for you.

Today’s Thought
The ancient sailor said this to Neptune in a great storm, “O God, thou shalt save me if thou please, if not, thou shalt lose me; yet will I keep my rudder true.”
— Montaigne, Essays

Boaters’ Rules of Thumb, #112
Rudder efficiency. The average sailboat rudder will stall and lose efficiency if it is put over more than 35 degrees from dead ahead. In fact, it will act as a good brake if you are approaching a dock too fast and you can put it over to 90 degrees, first one side and then the other.

Tailpiece
“And you, madam, what’s your husband’s average income?”
“Oh, usually well after midnight.”

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

All about rudders

THE SUBJECT OF today’s lecture is rudders. Like teeth, rudders are very nice to have. Rudders allow you to steer the boat, something that is so highly desirable that it makes you wonder why Western “civilization” didn’t adopt them until the year 1200 or so. Before that, Western vessels were steered with paddles or oars, usually slung over the starboard (steer-board) quarter.

In passing it should be noted that the Chinese are known to have had proper rudders in about 200 BC – 1,400 years before the idea occurred to Europe’s brightest spark.

Of course, the subject of rudders is not very exciting for most people. Rudders are usually hidden underneath the boat somewhere, and only warrant scrutiny if the boat is hauled out for bottom painting or repairs. Even when you can see a rudder (or part of it) hanging off the stern of a boat, it doesn’t arouse much excitement or passion.

Neverthless, the subject of today’s lecture is rudders, so we shall press on.

Rudders are quite large in sailboats, compared with those of powerboats, for better control at slow speed. But even though they’re big, they won’t work if you turn them more than 35 degrees away from dead center. More than 35 degrees and the whole rudder blade will stall.

If you have a tiller, it’s easy enough to see when the rudder is being pushed over too far. On a boat with wheel steering, however, it’s a good idea to fit rudder stops to prevent the rudder from turning more than 35 degrees either way.

The rule when you’re using a sailboat’s auxiliary engine in reverse is to hang on tight to the tiller, because if you give it half a chance the rudder will slam over hard one way or the other. Even if the spinning propeller doesn’t chew a big hole in it, the tiller might thump you in the ribs.

It doesn’t need much brain power to figure it out, of course, but the farther aft a rudder is, the more leverage it has to turn the boat. That’s why a transom-hung rudder is more efficient than one whose stock comes up through the cockpit floor. I prefer rudders fixed to the transom, not only for their better turning power but also because if something goes wrong, they’re easier to fix, with their readily accessible pintles and gudgeons. I used to like to talk about pintles and gudgeons around the office water cooler when I was younger. It made me sound like I knew something and the girls would flutter their eyelashes at me.

Many racing sailboats have balanced rudders. They have a small portion of the rudder area in front of the rudder stock to make steering easier, say 15 to 17 percent in front, and the rest behind. I once had a Santana 22 that was like that, but she suffered from lee helm in light weather and the balanced rudder made her wander all over the place. It was very tiring for the helmsman.

Cruising boats don’t need balanced helms. They benefit more from a rudder hung from the end of a full keel, or from a skeg. Such a rudder offers less resistance when it’s turned, and allows for a less disturbed flow of water to the rudder blade.

I see some of you are nodding off already, so I’ll cut this short by saying that the whole subject of how a rudder steers a boat is quite fascinating. It involves a wedging action of the whole length of the hull once the rudder has initiated a turn, and the hydrodynamics are extremely interesting. Well, I, at least, think they are, but I can spot a lost cause as well as anybody. So I’ll just finish by urging you to think good thoughts of your rudder next time you’re sailing. You need your rudder more than it needs you.

Today’s Thought
He who will not be ruled by the rudder, must be ruled by the rock.
—Isaac D’Israeli, Curiosities of Literature

Tailpiece
“Hey, Fred, that cow you sold me dropped dead last night.”
“Gee, that’s too bad. She never did that before.”