FLEXIBLE SPARS, A Pamphlet “LITTLE BUT PERFECT”

FLEXIBLE SPARS
A Pamphlet "LITTLE BUT PERFECT"

Describing their Theory and Use
by Walter von Hütschler

Published and Distributed by Courtesy of
PARKMAN YACHT, INC.
51 East 42nd Street
New York, N.Y

This pamphlet is dedicated to the Star Class. Long may it flourish and spread good fellowship throughout The World.
- Walter von Hütschler                                 

FOREWORD

Throughout the years that led the Star to world‑wide fame, the rig has undergone four changes but the sail area and hull remain the same. The gaff rig gave way in 1921 to the short marconi, which in turn was supplanted by the tall marconi in 1930. These decennial improvements were necessary to keep the Star from becoming antiquated but flexible spars, which must be looked upon as an operation rather than a different rig since they involved no change in the specifications, anticipated future developments and gave the Star something far in advance of any other one‑design class.

In the World's Championship of 1937, PIMM'S performance was so convincing that the merit of flexible spars was almost universally acknowledged. Stars, old and new, were quickly converted. Few, however, among the skippers, builders and sailmakers had more than a rough idea of what it was all about. The novice was completely confused while even the most experienced were doubtful as to the finer points of spar flexing. Many and varied ideas were advanced. One man only was, and still is, in a position to answer authoritatively the questions in the minds of so many Star skippers that man is Walter von Hütschler, who originated and developed the flexible rig.

It is in the spirit that the last word has not as yet been said on this all engrossing subject that Parkman Yachts, Inc. presents what might well be considered the first authentic word. It is our hope that the following pages, written by Walter von Hütschler, at our request, will be of some value to Star owners and may prove a helpful contribution to yacht racing as a whole.
- PARKMAN YACHTS. INC.

INTRODUCTION

In the world of Stars, flexible spars have proven superior, beyond a doubt, to the rigid mast and boom. Members of the Class have been wondering for a long time how the flexible rig should be operated. I feel that in what has been publicly stated and written all the correct answers have not as yet been given. Things have been overestimated and overdone to some extent and, in consequence, have become unnecessarily complicated.

This little pamphlet is therefore written in an attempt to untie the knots. It will be seen that the flexible rig can be easily operated by the average yachtsman. It may be disillusioning to some, but the story of how the flexible rig was conceived and gradually developed is devoid of any inspired flashes of genius or sleight‑of‑hand tricks. It did not occur to me, one lucky day, that Stars should have a flexible rig, nor was this rig worked out in one night and put into practice the following week. It took years - years of perfecting every detail. Only common sense was applied and only such simple lines as are known to the average racing skipper were followed.

This is how it came about. I simply tried to save weight aloft - an obvious advantage. I kept making my mast and boom lighter and lighter, until one day the boom would not stay rigid. When my friends first saw this "bending boom", they thought I had gone too far in my effort to save weight. With the claw way aft on the boom, as was common practice on all keel yachts at that time, my boom naturally bent so much that it spoiled the set of the sail. But I soon found out that by shifting the claw forward, the foot of the mainsail conformed to aero‑dynamic principles more so than when a rigid boom was used.

This experience led me to try to apply similar conditions to the mast. By tightening or loosening the shrouds, (upper, middle, and lower) the mast would bend and by doing so, it vitally improved the aero‑dynamics of the mainsail. It is important to note that even at this early stage, the mast and boom assumed a curve due to nothing more than the increased pressure of the wind on the sail.

Naturally, with these changed conditions in the rig, with parts moving, instead of remaining stationery, many new fittings and gadgets had to be devised, and painstaking care had to be given to all details it took years.

In 1932, after thirteen years during which I chiefly raced centerboard boats, I sailed my first Star, No. 898. I won the eliminations in my Fleet, but only finished 15th out of 28 entries in the World's Championship, then known as the Internationals, which were held that year by the Central Long Island Sound Fleet. By better sailing, I might have improved my position by several places, but 9th or 10th is the best I could have hoped for. No. 898 was too heavy and clumsy. I improved that boat slightly the next year. In 1934, I was so tied up with my business that I never even touched a boat. The following year, my next Star, No. 1078 was built. I sailed her for two seasons, and it was with this boat that I tried most of my experiments.

"PIMM", Star No. 1420, and incidentally, the sixth boat by that same name which I have owned, was built in 1937.[1] This was the "PIMM" that I raced in the World's Championship of that year at the Western end of Long Island Sound and that caused quite a sensation by winning four races. This focused attention on my spars and sails and marked the debut of "flexible spars", a term which was coined during that Series and has applied ever since. It was not until then that I realized I had stumbled across something in the way of a real achievement. All that I had been aware of up to that point was that I had been making an effort to get my Star to go faster, the same as any other racing skipper.

I will try in this pamphlet to explain the results of my experiments and offer such advice as I can. But before doing so, I would like to emphasize the fact that I fully realize that time and further experimentation on the part of others may improve or even radically change the opinions which I now believe to be correct.

Yachting, as compared with other sports, has the least reliable method of checking effects and results. Take, for example, the use of a large Genoa jib or the use of a smaller one. The big jib certainly does more work than its infant brother. But how, when, and where does the Genoa interfere with an even flow of air along the mainsail? How and when does it disturb the balance of the boat? When will it be a handicap simply because it makes the boat slower in going about? At what point does it begin to make your bow bury in a heavy sea? Finally, on what course and at what wind‑velocity will it prove to be just about too much canvas? There are no mathematicians or scientists who can tell you this, with any degree of certainty. At best, there are only a few yachtsmen who have taken the trouble of getting anywhere near the right answer. These few are certainly headed by Harold S. Vanderbilt.

Although the foregoing may seem to have little bearing upon flexible spars, the fact that there is little reliable data, and most assumptions are as yet unproven, is a most important factor and should constantly be kept in mind when yacht racing problems are being discussed. Please apply this right here and take all that I may say in the following pages as constituting what, at present, I believe to be right.

EDITOR'S NOTE

Walter von Hütschler made his American debut in the Star World's Championship of 1932. Profiting from the experience gained, he soon became one of the foremost small boat skippers in Europe. In 1936, he won the European Star Championship for the Hamburg Fleet, but was not eligible to represent Germany that year in the Olympics since he was a Brazilian. In 1937, be won 4 out of 5 races for the World's Championship on Long Island Sound and admittedly would have won the Series were it not for an accident in the first race. In 1938, however, he won the title at San Diego, California and successfully defended it again in 1939 at Kiel, Germany - an unequaled record.

FLEXIBLE SPARS

THEORY
Here in a few words is the theory of flexible spars. The luff and the foot of a mainsail are made, generally speaking, in the shape of a long convex arc (roach), and when these two curved sides of the sail are pulled out straight on straight spars, it naturally creates a bag (draft) in the sail. If the spars are reasonably pliable and can now be made to take approximately the same curve, this will obviously evenly remove the bag, flattening the sail. A simple, though crude, example would be to flatten a portion of the rim of a drum. The drumhead would immediately become slack and baggy. Spring the rim back into its original shape, and the drumhead would again be taut and flat. If the rim did not spring back into exactly its former curve, wrinkles would remain on the drumhead. Similarly, wrinkles or hard spots will appear in the sail if the flexing operation is not correct.

ADVANTAGES
Now let me give you my conclusions, based upon personal experience and observation, regarding the practical advantages of flexible spars. There are many factors connected with yacht racing which are as yet by no means a perfected science and that is probably why this sport is never lacking in interest. I repeat, therefore, that the following is submitted subject to such future amendments and changes that time may bring forth.

The advantages of the rig are manifold. The greatest advantage is that some draft can be taken out of the sail when close hauled on the wind, and in a freshening breeze. Two mistakes are frequently made that deprive the user of this most important advantage.

First, the amount of draft that can be absorbed by flexing the mast and boom is generally overestimated. This is dangerous and can be most harmful, as it results in bending the mast too much. This practice accounts for the loss of many spars and for the ugly deformity of mainsails. The manufacturers of spars and sailmakers are usually blamed, which is wrong in nine cases out of ten insofar as the spar manufacturer is concerned, and in 60% of the cases insofar as the sailmaker is concerned since the building of spars is not quite as much of an art as sailmaking.

Second, the other mistake most frequently made which results from the same erroneous idea as the first is that mainsails are ordered cut so full on the luff and foot that even with the mast and boom bent to their utmost, the draft in the sail cannot be removed, remaining almost maximum and only fit for light air. All that is gained is a few square feet of cloth, but this is too small an advantage to offset the real advantage gained by spar flexing.

Flexible spars should, theoretically, give you two sails in one, a sufficiently drafty sail for running and reaching, and for a relatively light breeze when the spars are straight, and at the same time, make it possible to obtain a flatter sail when close‑hauled in a freshening wind.

DRAFT RANGE
You must not mistake the foregoing statements to mean that flexible spars make it possible for you to use one sail that will be efficient under every possible condition from the lightest air to a gale. It must be remembered that flexible spars have their limitations, and that no matter how much the spars are bent, they cannot flatten an exceptionally baggy sail. A happy medium can only be reached if the sail has no more draft to speak of than was originally in a reasonably full sail used for the old rigid spars.

You can, however, have an ideal sail for light air when the mast and boom are straight and still have a sail that is ideal when close hauled, with spars bent, for a wind of 12 or even possibly 14 miles. Such a sail will most certainly give you a decided advantage over the ultra‑baggy sail, whether it be used on flexible or rigid spars. A sail of the latter type is suitable only for a drifting match of a character that is not apt to finish within the time limit. They have so much draft that the spars cannot begin to absorb it when flexed, and such sails might just as well be used on rigid spars. A Star championship or anything that deserves to be called a race has to be sailed in winds averaging at least around 5 miles p.h. In a 10 mile Star race that finishes just within the 3 1/2 hour time limit, the wind is usually inconsistent in velocity, and there will be spots where it falls off to around 2 miles p.h., and others in which it may perhaps freshen to 8 miles or over.

There can be no doubt but that the boat which uses the sails first mentioned on flexible spars, properly handled, has a great advantage over the ultra‑baggy sail, since it can regulate the draft according to the increase or decrease in the velocity of the wind. This boat will be better off than the one that has nothing but a few more square feet of sail. It has the further advantage, should the wind happen to blow up to a real breeze of say 8 miles, of being able to reduce the draft somewhat. Flexible spars will not be able to absorb enough draft in a sail such as we are discussing to make the sail of ideal flatness, but it will be enough to keep the boat manageable on the wind, while those with abnormal draft will be floundering around helplessly and scarcely able to point at all.

Do little but perfect! It is better than attempting a lot and doing it wrong. So do not expect your flexible rig to give you a flat sail when needed, though you have ordered your sailmaker to make one as baggy as money can buy. Order a sail with the same draft as you could reasonably carry on a rigid mast and boom, and you will have a sail suitable for the purpose we are discussing.

Since a flexible rig, properly used, will flatten a moderately baggy sail, sufficiently for a breeze of up to about 12 miles, it follows that a second sail is essential for winds of greater velocity. This second sail should have just enough draft on straight spars for winds of around 12 miles. With spars flexed, it should flatten to suit winds of up to 20 or 25 miles. Naturally, three mainsails of different draft are better than two and two are better than one, but no matter how many sails a person can afford, the flexible rig gives the enormous advantage of altering a given sail so that its draft can be made ideal within a range of nine to twelve miles in velocity, whether it be a light air sail, a medium weather sail, or a heavy weather sail.

As to the jib, its draft cannot be altered by means of any rigging device, nor is this so important on a Star. Two jibs, one on the full side and the other on the flat side, are plenty. Whatever the amount of draft in a jib may be, be sure it is the forward longitudinal quarter.

In neither the jib nor the mainsail should the roach be exaggerated, although this is often the case. I may be wrong, but I feel that the amount of roach allowed under Star rules is a little too much for the good of the mainsail. I have never, as yet, seen such a sail that did not quickly go out of shape - if it ever was perfect in the beginning. So here again - do little but perfect! The batten length limits any advantage that can be gained by an excessive roach.

BREAKING IN SAILS
Incidentally, any number of sails over three, in my opinion, will prove to be a handicap. There is hardly a man who has the time and patience to break in more than three suits of sails. Breaking in a new mainsail is usually done in much too little time. The average Star mainsail should be given 25 to 40 hours at least of easy going before it can be safely used in a race.

Speaking of sails, it might be mentioned here, that many a good sail is spoiled because it gets its first rain during a race. There is no question but that it is better to keep a sail out of the rain altogether. We cannot, however, provide sunshine for every race. It is wise, therefore, to take one sail and break it in during a rain. Keep the sheets eased and do not let the sails take more than a wind of about 10 miles p.h. Do all this after you have gone through the same procedure with the same sail in sunshine. This means a lot of time spent on one sail, but, though time is money, it will prove to be cheaper than spoiling a good mainsail every time you are caught in the rain.

FLEXING THE MAST
So far we know that the flexible rig can alter draft in the sail within certain limitations, and have perhaps learned a little of how to treat a sail. We have yet to discuss how to properly handle flexible spars.

It is generally believed that the mast should be curved by pushing the sliding partner forward by force, with the mast kept in position at the step by the mast raker, and with pressure on the backstay while at the same time slackening the jibstay and headstay. The same effect can naturally be obtained by holding the mast in position at the upper spreaders, locking the sliding partner at deck in a straight‑down line, and forcing the mast aft at the step by means of the raker. Both of these methods are the same, but both methods, in my opinion, are wrong.

The curve in the mast should not be forced, but should be achieved only through the medium of the mainsail. This, as you will sees is the easiest and most natural way, and further, almost automatically adjusts itself. Forget the idea that there must be a forward pull at deck, and an aft pull at step and at the upper spreaders. Consider instead an aft tension at the head of the mast, a forward tension at the upper spreader produced by the jibstay, and an aft tension on the step.

Provided the headstay is slackened, you will get an after tension at the masthead by trimming down on the mainsheet. In light air, with hardly any tension on the mainsheet, there will be less aft tension at the masthead and that is exactly what you want. The more the breeze freshens, the greater the downward pull or tension on the mainsheet, when close‑hauled, which in turn bends the masthead aft and the sail flattens automatically. Then again even in a moderate breeze, by easing the mainsheet on a run or reach, the downward pull will decrease, the aft tension at the masthead becomes less, the mast straightens up, the sail becomes more drafty - and that again is exactly what you want.

Now when the masthead falls aft (the jibstay takes up the tension at the upper spreaders) as explained, naturally the mast will tend to spring forward between the lower spreaders and the deck. This is desirable. In itself, however, this may not be enough. So you take the forward and aft position of the shrouds at the chainplates to help this effect. The more the lower shroud is carried forward, with the middle shroud taken aft, to compensate, the more the mast will be apt to spring forward at the lower spreaders. To some extent, this will be enhanced in a blow because of the greater tension on the shrouds. It will be decreased in light air when the shrouds are hardly holding anything - and here again is what you want.

With few exceptions, all masts of normal weight and strength will bend sufficiently under the conditions which I have thus far outlined. If, however, this should not prove to be enough, and only then, should the procedure of forcing the sliding partner forward and setting up the backstays to the tightest point be resorted to, although the sliding partner should only be used to help flexing under such extreme conditions, this fitting should, nevertheless, be a part of every Star's equipment from the point of view of safety and to facilitate tuning.

Look out for one dangerous point, in between the deck and the lower shrouds. With the lower spreaders only slightly too far forward or aft, the mast may tend to buckle either way, breaking down under its own load. This you can prevent with the aid of the sliding partner.

It may interest you to know chat "PIMM's" mast trouble in the first race of the 1937 World's Championship was caused by the lower shrouds not being far enough forward. The mast took on an "S" shape. It bent aft at the top, forward at the upper spreaders, aft again between lower spreaders and deck, and forward again at the step. I had nothing on the deck to prevent the mast from getting out of control, the hole at the deck being purposely made larger to allow the mast to bend and straighten. If I had had a sliding partner, my trouble would have been quickly cured, but as it was, the mast split before I could do anything about it.

I have heard that following the 1938 World's Championship at San Diego, quite a discussion arose in America as to whether or not "PIMM's" mast was flexed. It was stated by some, who claimed to have watched me carefully, that I did not adjust the "PIMM's" mast during a race. Others insisted that I did and, in proof of their contention, pointed to photographs of the "PIMM" which showed that the mast had a curve. As a matter of fact, both were correct, for while I did not bend the "PIMM's" mast, it was so adjusted as to automatically bend itself. As a result of this controversy, many who were wavering in their opinion as to the merit of flexible spars, hesitated to convert feeling perhaps that they were not a decided advantages or at least, that too little as yet was known about the theory. I hope that my views as expressed in this pamphlet will not create a new misunderstanding. The flexible rig has definitely proven its advantage over the old rigid spars, even with the mast being bent by force. All I have been attempting to point out is that, in my opinion, the maximum efficiency is obtained from the flexible rig when it is so adjusted that the mast automatically bends of itself.

POSITION AND TENSION OF SHROUDS
It is difficult to specify the exact position of the shrouds on the chainplates or the proper tension which they should have since there are no two masts quite alike. Wood is not a homogeneous material like iron and steel. Wood is a growing, living substance and, as a result, stronger and weaker parts are frequently found in the same piece. For this reason, a solid or one-piece mast cannot be as strong as a built‑up mast. In a three‑piece laminated mast, for example, the builder can compensate for weak spots by reversing the grain, and gluing stronger sections to. the weaker ones. Even so, masts never have the same exact stiffness which should correspond to their diameter at every point. It can also happen that a mast has more strength to resist a forward pressure than an after pressure or visa versa, and this also applies to a possible difference in resisting a port or starboard pressure. It may even be necessary, in some cases, to have the port shrouds in a different position than the starboard shrouds in order to compensate for such a tendency, so that the boat will handle the same on both tacks.

As you see, it is difficult for me to give any specific advice as to exactly where the turnbuckles should fasten to the chainplate. Here, however, is the approximate position. The lower shroud turnbuckle should be forward of the mast center, a distance equal to the mast's diameter. The middle shroud turnbuckle should be aft of the mast center, a distance equal to half of the mast's diameter. These positions are, of course, approximate, and there should be some quick method of making changes in the position of the turnbuckles on the chainplates. If for no other reason than this, the regular above‑deck chainplates with ample range, are better than any underdeck arrangement because you can see what you are doing.

The tension of the lower and middle shrouds should not be the same. I believe it is better to keep the lower shrouds almost slack and the middle shrouds fairly taut. Opinions differ as to the advantage of a diamond or non‑diamond rig for the upper shrouds, but I think that in Stars the diamond is better. The upper shrouds should be as taut as can be within reason. The diamond, especially when it leads back down the mast to a turnbuckle that can be easily reached, gives some added elasticity, and the convenience of being able to make adjustments without climbing the mast or having to do so from a dock.

The position of the spreaders on the mast should be somewhere around 12' 1" above deck in the case of the lower spreaders, and 22' 3 1/2" in the case of the upper spreaders. The length of the lower spreaders should be approximately 24" and of the upper spreaders 19". The play fore and aft should be possibly 2" to 3" at the outside end of the lower spreaders, and perhaps 1" at the outside end of the upper spreaders.

A lateral play of the mast at deck is a good thing for many reasons. Some of the most important are that there will be a certain elasticity when working in a choppy sea; there will be an easy way of checking the correct and equal tension of the lower shrouds; and it tends to prevent the mast from falling off to leeward. The mast should travel an equal distance of about 1/2" at deck to leeward on both sides from the center.

BEWARE of the mistake of using too light a mast and or fragile mast fittings, also of too many perforations which tend to weaken the wood fiber... it does not pay! Too heavy a mast, I mean, of course, within reasonable limits, might cost you a place or two in light air. Instead of coming in first you might finish second or third. But losing your mast (for there are few Series in which there will not be at least one good stiff breeze or squall) means losing everything that can be lost. You will even be worse off than the boat that crosses the line last with no points at all in that race.

BOOM AND DECK FITTINGS
There now remains only the question of the boom. This is very simple. The roller claws are so placed along the boom that it may be bent as desired and where desired by the pressure exerted on the mainsheet. The boom should not be abnormally light. Here again - nothing should be overdone. It is better to have two stern travelers as this gives more margin in changing the position of the claws. They should be about 18" and 28" respectively forward of the transom. The cockpit traveler should come in about the middle of the cockpit. The stern travelers should have stops so that the slides on which the blocks travel can be kept within any range desired. It is also advisable to have some quick and simple method of changing the position of the claws on the boom.

Needless to say that good working and practical fittings, such as adjustable backstays that will not slip, compact but strong roller reefing gear, a device for shifting the position of the jib leads, a jib winch, etc., are essential to all racing craft, and many such fittings have already been especially designed to meet the particular needs of the flexible rig. Here, too, of course, though lightness is desirable, durability and strength should not be sacrificed in order to attain it. An ingenious, though reasonably simple fitting is perhaps better than a complicated one that may get out of order when needed have sufficient fittings to meet every need of the flexible rig but do not complicate matters with a lot of useless gadgets whose advantages are questionable.

It would not be right to finish this little pamphlet without a warning, especially to the beginner. Do not think that the flexible rig is too complicated for you, and that you can never hope to master it. Do not follow my directions too literally, but just use your own common sense as much as possible. Grasp the principle idea of the thing that the mast will flex properly under the tension of the mainsheet, provided you let go the headstay a little. Do not expect and do not try to do everything right the first day you are out in your boat. If you do, you will fare badly, for after all, regardless of your rig and its manipulation, you still have to concentrate on sailing a good race... so remember, ‑ do little but perfect!

(Parkman notes)

WHERE TO GET AUTHENTIC FLEXIBLE SPARS AND FITTINGS USED WITH THIS RIG - PARKMAN YACHTS, INC.,

Since the fall of 1937, have built flexible masts and booms of the exact name dimensions as those used by "PIMM". These spars are not merely limber, but of correct shape, proportion and strength, with properly placed fittings, to produce efficient flexing. Parkman Deck Fittings are especially designed for use with the flexible rig and permit quick, accurate adjustments, enabling skipper and crew to easily carry out the correct theory of spar flexing as described in this pamphlet.

The reputation of our Star is due to performance over a long period of years in the hands of average skippers.

The Parkman Star is being improved from year to year and each season shows a greater number of series won.

Hull weight of a Parkman Star with mahogany frames about 400 pounds, with spruce frames 370 pounds.

Innovations the world over are constantly studied and the more feasible principle incorporated in Parkman Fittings.

Of the many Parkman Flexible Mast built and equipped with our fittings ONLY ONE has been carried away.

Our socket type Backstay fitting has an 18" range. Latch cannot slip when locked or catch when released.

A catalogue describing Parkman Star Fittings and Accessories may be obtained without obligation upon request.

Our Roller Gear operates by hand, no handle to catch in halyards or be lost.

We also have Reconditioned Stars, Used Stars and Trailers.

Our Crank Action Partner is controlled from cockpit. It has an inch gauge for accuracy.

Our MAST RAKER is operated by same crank as the Partner and adjusts position at step.

Our FLEXIBLE MASTS are grooved and built up of three pieces. Our ROLLER BOOMS are to grooved and laminated.

Our Turnbuckles can be quickly adjusted on our wide range chainplates

Our Collar Fittings on mast carry the tang and obviate use of many long bolts through the mast.

With a PARKMAN STAR there is little to do to be perfect. The boat is already practically in tune.

In August 1940, construction was begun on "PIMM TOO" at the Parkman Yacht's Plant in Brooklyn. This will make Walter von Hütschler's seventh "PIMM".