Yachts - Set The Racing Sails
( Originally Published 1911 )
THE set of the racing sails, the all-important factor, the only means of propulsion for the wind-driven craft, means something in itself, as the yacht with this power alone moves at a speed faster than a great many of the largest steam yachts.
The curvature, smoothness, correct cut and shape, rigidity, and staying power of the cloth, sometimes as light almost as a hand-kerchief, are great factors in the yacht's speed. Do not treat the sail as an inert object, there is life in its every movement, and it is the engine that drives the yacht, the wind, the power.
This subject cannot be covered in a chapter or a volume, or possibly in many volumes, as there is considerably more in a sail than appears to the casual observer. Men of brain and thought have worked for years trying to find out the correct sail and reach a belief in certain theories, only to have their ideas shattered at some future time. It seems al-most an impossible equation to solve the power of wind on sails. The best sailmakers of to-day differ in their opinions as to how the different sails should be cut, fullness here, fullness there, a little more sweep to foot or head, the angle of the gaff to the hoist, and a thousand other details. Who is correct ? Some say one, some say another, but nobody knows. Is it a possible thing to ever find the correct answer ?
How should the sail be made to get the greatest driving power, point into the wind's eye, and have the least resistance for the movement through the atmosphere ? And again, should this perfect sail be changed in shape to suit more exactly the type of yacht it is going to drive ? There is no doubt about it. The sail should fit the boat's model ; that seems to be the general opinion, but we do not actually know it ; it is simply an opinion.
On the present small racing yachts of the knockabout type, where the area is restricted to small sails, the best mainsail, with the greatest driving power, is one cut with a fair amount of draft or fullness in by the mast, an easy sweep to the center, and flattening out to a flat plane at the leech. This makes a nice hook for the positive pressure to work in and drive the boat ahead, and also allows the negative energy of the wind to escape freely and with the least possible resistance over the flat after end of the sail, this, of course, applying on windward work alone. Off the wind the entire area is positive pressure and driving the boat ahead. I am not considering the action of the lateral plane on the water.
The jib should be of the same general idea, a little fullness along the hoist and a flat leech. If the leech of any sail has a tendency to hook over, wooden battens placed in pockets in the sail at right angles to the leech will flatten it ; and if it still has a tendency to angle over at the inner end of the battens, the sail needs hauling out on the boom and gaff. The expensive sails of to-day, cross-cut, that is, with the cloths running perpendicular to the leech, can be cut close to the limit on the measurements, as the tendency to stretch is very much lessened over the old-fashioned up and down sail. The reason for this is in the weave of the cloth. It is composed of a plain weave lengthwise of the cloth in the warp, and the cross thread is the filling. The filling thread shows almost no corrugation from the action of the loom, it being all in the warp ; there being thirty per cent take-up in the warp and ten per cent in the filling. This shows the amount of corrugation in the warp thread, and the minute strain is put on this cloth the warp has a tendency to straighten out, consequently stretching the cloth. Thus the cross-cut arrangement of cloths simplifies the matter for both makers and users.
In drafting the general plan for the shape of sails, keep the type of craft in view. If she is powerful, a high narrow rig with a high center of effort is advisable; if she is light and tender, make the rig lower. The boom at the mast should be well above the deck to insure a free draft of wind when heeled down in moderate weather, and the entire sail can be lowered down in a heavy breeze if there is a sliding gooseneck. The angle of the gaff to the mast should not be too small, as it is difficult to make the sail set with too high a peak. The jib should be placed well off the deck and preferably on a short bowsprit, in order to insure a good draft and the use of every square inch of canvas, providing there is no restriction on the fore triangle area. It should also be held well away from the mast so as not to throw back-wind into the mainsail. On the other hand, the jib should not be set too far forward, thereby spoiling the unity of the plan by so splitting it up.
A great many people believe in the high narrow rig, as the sail is then cutting a longer column of air than the lower rig with the same area would, but it is more difficult to make the high rig stand to its work in a breeze, and consequently should not be overdone.
The weight of the cloth is another important factor in the set of the sail. Five to seven ounce duck of the most expensive sort is about the right weight for a mainsail of five hundred square feet in area, with a jib of the same weight. For a mainsail of seven to nine hundred square feet the weight should be eight to ten ounce.
The light sails on the small racer should be cut and set correctly, as well as the working suit. It is well to have two sizes of spinnakers, as when there is enough wind blowing to lift the sail, then you can stand one of greater area, but in the light winds, either dead before it or slightly across the wind, the small sail will fill out and do its work better, as it is cut well off the water and does not lap past the mast so far. It thus allows a draft past its edges which the larger sail will not do. I believe thoroughly in the small spinnaker over the very large one, as it is possible to carry it well forward in a breeze and utilize it for a balloon jib, which sail is not allowed on most of the racing knockabouts. I have won many races solely due to a small, well-setting spinnaker carrying it even to windward in very light drifts, when on account of its light texture it was the only sail that showed full and drawing. Some people have a theory that you should put all the cloth possible into a spinnaker, regardless of the shape and set. This seems to me wrong, and I consider it an error to get the wind piling up against itself in a great bag, rather than a moderately flat sail that allows the wind a chance to escape around its edges, and in its stead getting the full force of the new air, which seems to have greater force and drive. Always keep your spinnaker pole as nearly at right angles as possible to the direction of the wind ; too much care cannot be used in this matter. Also the spinnaker sheet should be worked in conjunction with the guy, keeping the sail at all times straight across the wind, and not allowing it to fill out around the head stay, thereby getting back-pressure, as well as forward.
In balloon jibs the cut will vary according to the shape of the fore triangle. But the important thing is to be sure the luff is set up at great tension, as a slack luff will mean a poor sail. The sail should stand well off the deck and water, so that the lee-bow wave shall not be thrown into it to any great ex-tent. It should also come fairly well aft, to allow for bellying out to leeward, as the sail is not carried to windward in a breeze on ac-count of being made of too light duck, and also because of the tendency it has to back wind the mainsail.
The No. 2 balloon sail, or sometimes called "reaching jib," is made of heavier cloth, cut considerably smaller, and can be carried with the wind fairly well ahead, even to windward in light weather.
In reefing, great care should be used in pulling the sail out on the boom. It should not be more than hand stretched, and if there is rain or fog during the race, be sure to shake out your reef on returning to the mooring. It is also a good idea to loosen up the head and foot on the spars and allow the sail to shrink evenly as much as it will, rather than hold it taut on the spars while the center con-tracts, thereby getting a hollow leech. Little points of this sort are invaluable in the life and set of the racing sail, although a little more trouble at the time.