Jim Jeffreys: Hi! I'm Jim Jeffreys. I'd like to welcome to the raising sailor. The terms I describe the parts of boats originated hundreds of years ago, and while some of terms may seem strange or orchard. They are the same on all boats; this means that whether you're sailing at Dinghy or an America's cup boat. The Bow is still the Bow, and the Stern is still the Stern. The nautical language is universal and can pass language barriers and ultimately provide a safer experience for all involved. Here then are the basics.
The Hull is a part of the boat that goes in the water; the bow is forward, left is Port, and right is Starboard. The rear of the boat is called the Stern about the direction to the rear is called Aft. Thus, if you're in the back of the boat, you're in the Stern, but if you're walking through the Stern, you're moving Aft. The part of the boat where you steer and sail at front is called the Cockpit. If your boat has an inside, this is called Cabin. Underneath the boat is the Rudder, which allows you to steer, there will also be a Keel or Centerboard depending on the size of your boat. The Keel or Centerboard prevents the boat from sliding sideways, when the wind blows.
The force generated by the sail is primarily forward and sideways. By contracting the sideways force, the Keel allows us to move forward under the remaining force. Above the Hull of a sailboat rises the Mast. The Mast supports the sails and on larger boats may also carry lights and antenna. The Boom attaches low on the Mast and points Aft and between it and the Mast stretches the Mainsail. Forward of the Mast on many boats is the Foresail, which attaches to the top of the Mast and to the Bow. The most common types of Foresail are the Jib, the Genoa, and the Spinnaker. The leading edge of the sail is called the Luff while the trailing edge is called the Leach. The top is called the Head; the bottom is called the Foot.
The rounded part that bows out is called the Draft. A sailboat is covered in ropes and pulleys, although they're referred to as lines and blocks. The lines that control sails are called sheets, the Mainsail is controlled by the mainsheet, and the Jib is controlled by the Jib sheet. If you're using a Genoa or Spinnaker those are controlled by you guessed it Genoa and Spinnaker sheets. The lines called Halyard serve a dual purpose, their primary function is to raise and lower the sails, but as we'll see later they can have an affect on sail shape as well.
Sailing predates accurate compasses, so it is not surprising that the method for dealing with direction does not evolve points of the compass, radiating from the center of the boat that horizon is divided into 32 pieces or points. Forward is dead ahead behind is dead Stern and the either side is a beam. Halfway between dead head and a beam is broad on the Port or Starboard above depending on which side you're talking about.
Halfway between dead Stern and a beam is broad on the Port or Starboard quarter. A sailboats relationship with the wind is very important and there are number of terms that refer to it. Windward indicates the directions from which the wind is coming. The wind is blowing from the Port beam and you turn the Port causing the wind to come from ahead, you have turned to windward. Likewise, a boat that is upwind is to windward of you. The opposite of windward is Leeward.
When the Portside is windward the boat is said to be on a Port tack, when the Starboard side is windward the boat is said to be on a Starboard tack. When two boats meet the boat on a Port tack must always give way to the boat on a Starboard tack unless an abusible makes this is impossible.
This is a simplification of the original rules of the road to the see, which are very complex.
One element does survive however; a boat to Leeward always has the right of way over a boat to windward. If two boats meet and one is heading downwind and one is heading upwind, the boat heading downwind will always be to the windward of the boat headed upwind. It is much easier for the boat heading downwind to alter its course slightly, then for the boat heading upwind to tack. Maneuvers toward the wind are referred to as upward maneuvers. You'll hear many terms, head up, harden up, Luff up, and point-up while each of these mean something slightly different. The most important component is the up reference; these all mean, turn your Bow closer to the wind. Maneuver in a way from the wind is a downward maneuver.
Ted Beier: Following off, being knocked, bearing away those are all terms that mean that you're going away from the basic or original wind direction.
Jim Jeffreys: I like a powerboat, if sailboat cannot sail directly into the wind. A sailboat can however, sail toward the wind. Generally speaking, a sailboat can sail any direction up to 45 degrees from the direction the wind is coming from. This 90 degree wedge is referred to as the no goal or no sail zone. In order to sail, of course, directly to windward, a sailboat must sail as zigzag course called a beat, when sailing upwind a sailboat is said to be beating. While on a beat, progress is measured in terms of distance upwind, if a sailboat is sailing as close as it can to the wind with the best possible speed, it is said to be close hauled. It is possible to sail slightly closer to the wind, although you sacrifice speed and increase the risk of stalling by doing so. This maneuver is called pinching.
Pinching covers more upwind distance with less total distance sail then close hauled but that allows speed makes this course generally less efficient in sailing close hauled. Sailing slightly down of close hauled is called footing, this gives you a little bit more speed, but we'll require sailing more total distance to reach the same upwind point as sailing close hauled.
As long as the wind is coming from forward of a beam, the boat is said to be on a close reach, when the wind is directly a beam, the boat is said to be beam reaching. With the wind coming from anywhere from the side and behind, the boat is said to be broad reaching until the wind is directly Stern; at which point the boat is running. The reach is fastest point of sail for sailboats. To understand why this is, you must understand how wind and sail interact and to do so, you must also be aware of the phenomenon called apparent wind.
When a boat is at rest, it is acted on by the true wind. This is the wind that moves across the body of water upon which the boat rides. However, once the boat develops forward motion the sailor will also feel a breeze created by the forward motion of a boat. The two winds that are acting on the boat and the sailor will combine to form the felt or apparent wind. When the true wind increases in speed the apparent wind shifts toward to the true wind.
When the boat accelerates the apparent wind is shifted toward the bow of the boat. Because that's the combination of two winds, the apparent wind will often exceed the true wind. While it is important to understand how true wind and boat speed combine to create apparent wind, the only wind that affects sail trim is the apparent wind. To understand how to properly trim our sails, we must understand what happens when the apparent wind meets the sail.
A sail is essentially an airplane's wing turned on its in, just as an airplane uses it's wings to generate the lift that keeps it in the air by turning it sideways; the sailboat uses the wind shape to generate lift that pulls the boat through the water. The force of a sail moving through the air will cause air to be swept out in around the leeward side of the sail. This effect is called updraft because it was originally used to describe how air float up and rounded airplanes wing.
As air approaches a sail, it has a tendency to attach itself to the sail you may have afford sailors referring to air coming unattached, when a sail stops. The microscopic layer of air attached to the sail is called the Boundary Layer; maintaining a smooth transition from updraft around the sail to the leach is the key to keeping the Boundary layer attached and it producing the lift that will drive the boat. The tail tails on your sail will indicate whether or not the air is smoothly streamy around your sail. As the attached air proceeds around the curve of the sails draft, it has a tendency to accelerate, faster air moving around the outside the sail spreads out causing lower pressure than on the windward side of the sail. This pressure differential between the windward and leeward sides of the sail will cause a sail to be pulled toward the low pressure. This force will be transmitted the Mast, which will pull on the boat causing the boat to move forward.
Once you've got the boat sailing, it is important to know a few things to keep it going. The air pressures on either side of the sail must be equal at the trailing edge, otherwise turbulence will be created that will disrupt the flow of air along the sail. To do this, a sail should curve in the forward 40% of the sail, then run straight and flat to the leach. If the sail is too deep the difference in pressure between the leading edge of the sail and the tray lid edge will be too great.
The boundary layer will not be able to remain attached and the sail will stop. If the wind is coming from a beam instead of close hauled, then the sails draft maybe much deeper as the incoming air is already heading in the right direction for a deep draft with a long curve. A Jib acts the same as the Mainsail in terms of air foil performance that will combine the effect that it has on the Mainsail, and that the Mainsail has on it, is pro-found. Because sails tend to maintain pressure behind them and since air will flow from the windward side of the Jib around the outside of the Mainsail; the Jib dampens the initial radical effects of the Mainsail on the air. This enhances the flow around the leeward side of the Mainsail and allows the Mainsail and Jib to sail the angles that would sail a Mainsail alone.
The Goal when trimming the Jib is therefore to keep wind flowing smoothly around the leeward side of the Mainsail. The air flowing at high speed around the leeward side of the Jib is subject to the same Boundary layer phenomena that the Mainsail, the difference in air velocity and pressure from the leading edge to the trailing edge must not be too great.
However, because the trailing edge of the Jib exists in the area of high speed, low-pressure air created by the Mainsail, the air on the leeward side of the Jib doesn't need to decelerate to maintain attachment. The Jib can generate a much greater pressure differential because the air flowing along its leeward side doesn't need to return to normal pressure until the trailing edge of the Mainsail. In a beam or broad read situation, you want to allow your boom to rise in order to allow your sail to twist, because a wings lift force acts perpendicular to its length, a sail typically pulls to the side as well as forward.
However, when the sail twists the lift generated by the upper parts of sail rotate forward and pull in line with the direction of the boats movement. It may seem confusing that the force that pulls the boat forward is partly generated by the boats forward movement, when this lead to infinite acceleration or what keeps sailboats from achieving light speed is the drag and duos by the Hull.
So, for every combination of sail area and Hull, there is a theoretical maximum speed. Longer water line length increases this maximum speed while it increase displacement, reduces it, since longer Hulls are heavier, they tend to displace more. Hull design is a compromise between these two factors. When heading upwind on coming air it doesn't have to change direction very much to travel around and sails, so not great deal of lift is generated. When reaching the wind is coming more across the boat allowing you to carry more drafting or sails, which generates more lift. When running downwind, the boats wind and true wind acted opposition to each other, so every knotted boat speed subtracts from the true wind.
Downwind running is only a result of the air pushing on the sail and not the lift generated by the airfoil shape of the sail, so boat can go no faster than the true wind. Thus the fastest point of a sail is a reach. Because the sail acts an airfoil in all points of sail besides it run, it's important to shape a sail like an airplane's wing and to trim it to the most effective angle relative to the wind, also because water exerts friction on the wind, slowing it near the water surface when the laft travels faster than surface wind.
So, you must account for this faster, higher wind by allowing the sail to twist. Let's explore how you do this by reviewing all the sail controls. The mainsheet is the most basic sail control regardless of size or complexity of a boat you sail, all sailboats have mainsheets. The mainsheet pulls the boom in and out changing the angle, which the sail meets the wind when the boom is very close the center of the boat, the mainsheet also pulls down on the boom, which attains a sail and removes twist.
Likewise, loosening the mainsheet when the boom is in tight will increase twists. The main Halyard may not seem like a sail control, but it is. The Halyard that you use to haul the sail up the Mask can be tightened or loosened to increase the tension on the leading edge of the sail. More attention on the Halyard will move the draft of the sail forward. The traveler adjust the ladder position of the mainsheet line, that is, it moves the point that the mainsheet attaches to across the bow because the mainsheet contributes more and more downward force as a boom gets closer to centered the traveler allows the boom to be moved in or out without changing the downward force of the mainsheet.
The boom wang is a device that exerts downward force on the mast. It may take many forms either block and tackle or hydraulic and may mount above or below the boom. The wang has two purposes to keep the boom from rising widely and to add to extra tension on the sail. Increased wang will tend to flatten the Mainsail and decrease twist by pulling or bending the boom down. The outhaul pulls on the clue that's the bottom rear corner of the Mainsail, tightening the outhaul tensive flat in the sail, and move the draft to the sail forward.
The Cunningham pulls down on the front edge of the Mainsail; much like the main Halyard this adds tension across the leading edge of the Mainsail, flattening the sail and moving the draft forward. The downhaul pulls on the boom add its connection to the Mast, very often the boom can actually move up and down at smaller distance in a track on the Mast by pulling down on the boom the downhaul adds attention to the entire sail. The leach is a trailing edge of sail; the leach line is a lightweight stringer line that runs along the leach.
Tightening it reduces twist in the sail by tightening the entire leach of the sail. The waxy runs from the top of the Mast to the stern of the boat, tightening it causes the top of the Mast to bend backwards at the same time forcing the middle of the Mast to go forward. This puts a great deal on tension on the Mainsail flattening it. Bending the Mast also moves the draft of the sail Aft. Different boats will have different combinations of these controls. That's important to keep in mind when trimming is the shape of sail that you're trying to achieve. Once you know that, you can use whatever combination of controls you have at our disposal to create that shape.
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