sails trimming - page 3
2.3 The Sails
If you stick with the sport, you will develop an intimacy with sails. But to the new sailor, sails are the things that make sailing hard. Yes, but sails are the things that make sailing interesting, as well as possible. Try to see them in those terms from your earliest introduction. Modern sailmakers have turned this ancient, simple devise into a highly sophisticated, richly subtle aeronautical instrument. You can make today's sails do remarkable things, and the range of possibilities is great enough that no sailor ever stops learning about sails.
As we discuss the language of sails, please bear in mind that the sail-maker designs into them an aerodynamic shape; no modern sail is a flat piece of material. But unlike aiplane wings, to which sails are often compared, our sails need to operate efficiently in a wide range of conditions and angular relations to the wind. Trim is about adjusting the shape and angle of the sails to maintain efficient forward movement in light air and heavy air, when the wind blows over the bow of the boat, the beam, stern, and all points in between.
That said, let's hoist the sails and have a look at them. it doesn't matter what boat you are on, and since there is no wind, we are not going anywhere just yet. So you won't be able to see that curve your sail-maker has designed into the sails, but we can have a look at their parts, for now, in order to establish our common language. let's begin with the mainsail, it being the one you will usually set first.
When not in use, the main is usually folded, or flaked, on the boom and held there with sail ties. Remove the ties, and then attach the halyard to the head of the sail. Halyards hoist sails, so all sailboats must have halyards. They are attached, usually with a metal shackle, to the upper corner of the sail, the head. Since they are triangles, all modern sails have three corners:
The forward lower corner is the tack. The clew is the lower, aft corner of the sail, and of course the head is the upper corner. If the main is flaked on the boom when not in use, then the tack is already attached at the intersection of mat and boom, or the gooseneck. Likewise, the clew is already attached to the after end of the boom.
So you have attached the halyard to the head of the main. The halyard must of course tun to the top of the mast over a pulley, and then come back down, usually inside the mast, to a point near the deck within reach. Some halyards are attached to the mast, some are led aft to the cockpit, but it doesn't matter. You still pull down on the halyard to hoist the sail. Notice how the front part of the mainsail runs up the mast in a groove at the back of the mast. Tension the halyard enough to remove wrinkles in the front of the sail. After you tie off the halyard step back and have a look at the mainsail.
The mainsail is a right triangle with the leech as the hypotenuse. However, if you draw an imaginary line from the head of the main down to the clew, you will notice an arc of cloth extending beyond that line. This is the roach. Without a roach, there would be no fair curve at the back of the main. Instead of flowing smoothly, the wind would grow turbilent as it flows off the back of the main. Further, the roach acts a kind of rudder when you are sailing to windward. You don't need to understand how this works. Just grasp the language.
Because the roach extends beyond the hypotenuse, it needs some additional support to maintain the desirable curve. That's what battens do, flat strips of some stiff material such as fiberglass, nylon, or carbon fiber inserted into horizontal pockets sewn into the leech of the main. Some battens are short, only about twice as long as the roach itself. Others run the lenght of the sail from leech to luff; these are called full-lenght battens, often shortened to full battens.
The bottom of the sail is called the foot. The foot of the mainsail is sometimes fixed to the boom by means of a boltrope tunning in a groove in the boom. In that case, the sailmaker adds extra cloth to the foot, called thr shelf, which allows the foot to curve when the outhaul is eased. There is a trend today toward 'loose-footed' mainsails attached hanging over the boom. This is lighter and cheaper, and it allows for a wider range of adjustments.
However, old sail – when the sail get tired the draft moves aft resulting in extra material in the middle of the sail. This material can jam when being pulled out. A new sail with proper draft will also help the boat’s performance. Think about an airplane wind that is not shaped correctly.
Since there is no wind, we can leave the mainsail up. Now let's turn to the headsail. The names of its corners (tack, clew, head) and its edges (luff, leech, foot) are the same as the mainsail But the headsail is a relatively simpler sail than the main, primarily because it does not require a boom. Its foot runs free, as it must, since the sail must be pulled from one side of the boat to the other with each tack and jibe.
Another difference between headsail and mainsail has to do with their leading edges, their luffs. The luff of the main is affixed in a groove running up the aft side of the mast. But there is only a wire, the headstay, to accommodate the luff of the headsail. So in our imaginary sail insoection, we can't merely say, 'Okay, now let's hoist the headsail,' until we determine the means by which its leading edge, its luff, is attached to the headstay.
If the boat is a dinghy or a small keelboat, the luff of the headsail will be attached to the headstay by spring-loaded clips, properly called hanks. After a day's sailing, small-boat headsails are usually detached from the headstay and stored below, which means that you will have bring the sail topside to the foredeck, attach the tack to a dedicated fitting at the base of the headstay, and then one by one clip the hanks to the wire. That done, you then tie the sheets, those lines that control the trim, to the clew of the sail. All that remains is to clip the halyard to the head of the sail-and hoist.
If it is a larger boat, one,say, in excess of 26 feet, chances are the head-sail will already be hoisted and rolled around the headstay on a roller-furling device. The roller furler has done more than any other single device to make sailing simpler, easier, and cheaper. The system consists of a thin aluminum extrusion fitted around the headstay from bottom to top. The extrusion forms a groove. A boltrope sewn into the luff of the headsail slides into the groove. At the deck level, this long extrusion is connected to a small drum around which the furling line is wounded. The furling line is then led aft along the side deck to some convenient place in the cockpit, and cleated.
Hauling on the furling line turns the drum and the attached extrussion spins around the headstay and thus rolls sail around and around the head-stay in a neat, tight furl. Then to unroll the sail-to set it-all you need to do is uncleat the furling line and pull on one or the other sheet.
The system offers enormous advantages. It allows you to leave the headsail hoisted and rolled when the boat is not in use, particularly convenient on bigger boats with heavy headsails. And in the old days before roller furling, if wind piped up requiring a smaller headsail, crew would have to haul the new sail onto the foredeck, unhank the bigger sail, hank on the smaller one, and reconnect the halyard before hoisting the new sail.