This Introductory lesson is designed to help familiarize you with basic aspects of sailing.
Basic Sail Terms
TERMS APPLYING TO BOTH MAIN AND JIB SAILS
- Head:Top corner. (Where halyard connects to sail)
- Tack: Bottom forward corner.
- Clew: Bottom back corner.
- Luff: Forward edge.
- Foot: Bottom edge.
- Leech: Backedge.
- Cringle: Metal reinforcement ring.
TERMS THAT USUALLY APPLY TO MAIN SAILS
- Battens: Wood or plastic strips that act as stiffeners for the sail. They help keep the leech from fluttering.
- Batten Pockets: Pockets sewn into the trailing edge of the sail to hold the battens.
- Roach: The unmeasured Sail area along the back edge of the Sail.
- Cunningham: The cringle (grommet) on the luff of the sail used to achieve luff tension for draft control. (sail shaping)
- Reef Points: The row of points where the reef ties (gaskets) are attached to the sail.
BASIC STANDING RIGGING
- Mast: The large vertical spar that supports the sail and boom.
- Boom: The horizontal spar used to hold and extend the foot of the main sail.
- Forestay: The wire (cable) that supports the mast from the bow and prevents the top of the mast from moving aft.
- Backstay: The wire that supports the mast from the stern and prevents the top of it from moving forward.
- Shrouds: The wires that support the mast from the sides and prevent it from moving athwartships. (sideways)
- Turnbuckle: Device for adjusting tension on shrouds and stays.
- Chainplate: Fitting that connects shrouds to hull.
- Tang: Fitting that connects shrouds to mast.
BASIC RUNNING RIGGING
- Halyards: Lines or wire rope used to hoist the sails.
- Sheets: Lines used to control the sails. Trimming is tightening the sheet to move the sail towards the centerline of the boat and easing is letting it out.
- Outhaul: Line used to tighten or tension the foot or bottom edge) of the sail.
- Downhaul: Line used to tighten or tension the luff (forward edge) of the sail.
- Boom Vang: Line used to pull the boom down. It prevents the boom from lifting which causes the top part of the sail to twist.
- Topping Lift: Holds the end of the boom up and prevents it from falling into the cockpit when the main sail is lowered.
Terms Under Sail
Sailing Terms Underway - Refer to Sailing Quadrant Image on previous page
The following six terms are points of sail:
- Close Hauled: Sailing as close to the wind as possible. (pointing)
- Close Reach: Sailing between close hauled and beam reach.
- Beam Reach: Sailing so that the wind is on the beam. (90 degrees)
- Broad Reach: Sailing so that the wind is behind the beam.
- Running: Sailing so that the wind is directly astern. The jib and main sails will be on opposite sides. (wing and wing)
- By the Lee: Sailing so that the wind is on the same side as where the main is carried. When running, this could happen if there is a wind shift to the side of the boat where the main is. Sailing by the lee is discouraged because it could result in an accidental Gybe.
- Tacking: Turning the bow of the boat through the eye of the wind.
- Gybing: Turning the stern of the boat through the eye of the wind.
- Luffing: The fluttering of a Sail when a boat is pointed too close to the wind or the sail is eased out too far.
- In Irons: The condition when the boat is pointed directly into the wind without steerageway.
- Windward: The direction from which the wind is coming.
- Starboard Tack: When the starboard side of the boat is windward.
- Port Tack: When the port side of the boat is windward.
- Leeward: The direction to which the wind is going.
- Head Up: Turning the bow of the boat towards the eye of the wind.
- Bearing Away: Turning the bow of the boat away from the eye of the wind, also referred to as bearing off or falling off
- Helms-A-Lee: Notification that the tiller has been put to leeward to cause the boat to come about. (tacking)
- Trim: To pull in... as in trim a sheet. (line)
- Ease: To let out... as in ease a sheet. (line)
- Overtrim: A condition where the sail is trimmed in too tightly for the wind direction.
- Undertrim: A condition where the sail is trimmed too loosely for the wind direction. The Sail will luff if undertrimmed more than a slight amount.
- Beat: Sailing to windward by means of a Series of tacks.
- Reefing: Reducing the area of a sail due to strong wind.
- True Wind: The wind speed and direction as seen by a stationary observer.
- Apparent Wind: The wind speed and direction as seen by an observer who is moving across the water.
- Weather Helm: The tendency of a sailboat to head into the wind if the helm is released. (letting go of the tiller)
- Lee Helm: The tendency of a sailboat to head away from the wind if the helm is released.
- Header: Change in wind direction towards the bow of the boat.
- Lift: Change in wind direction towards the stern of the boat. A header for a boat on port tack is a lift for a boat on starboard tack.
- Beam: The widest section of a boat, generaily across the middle.
- Abeam: The direction to either side of the boat. (90 degrees from the bow)
- Underway: When the boat is neither at anchor, made fast or aground.
- No Way: When the boat is stopped.
The Sail as an Airfoil - Sailing Upwind
As a boat sails into the oncoming wind, the sail splits and bends the airstream. As long as the boat does not turn too close to the direction of the wind (the eye of the wind) the sail can bend the flow of air towards the stern of the boat. The wind's energy is utilized when the flow of air is bent this way resulting in forward movement of theboat.
As the windstream separates at the leading edge of the sail, (the luff), the flow of air passes along both the windward and leeward sides. While the flow of air tries to go straight, it is forced to follow the contour of the sail. The wind blowing across the windward side produces a pushing force referred to as drive. The wind flowing across the leeward, (back side) tries to pull away from the surface of the sail creating a lower air pressure area along the back of the sail. This pulling effect is called lift. The lifting force accounts for as much as 70% of the sailboat's power when sailing to windward.
The jib in the illustration is used to increase the flow of air across the back side of the mainsail, helping to create even less pressure. This produces more lift, increasing the pulling force to windward. The use of the Venturi principle in this way on sailboats is called the slot effect.
A strong aerodynamic force is exerted in a sideways direction by the wind as shown in the illustration. The keel, situated under the boat, prevents the boat from moving sideways by creating a lateral resistance force.
These two forces combine to create the resultant force which moves the boat in a forward direction. The interaction of forces is what propels the boat up wind.
The sails should be trimmed so as to create the maximum lifting force. (See Trim) If the sail is out too far, the flow of air will not be bent as much as possible. If the sail is in too far, the flow of air will break away from the back side of the sail. Either case will result in less than maximum lift and less than optimum performance for the boat.
A different set of forces come into play when the boat is sailing downwind with the wind aft of the beam. The lifting effect is minimized since little wind travels across the leeward side of the sail. Most of the drive now comes from the wind acting as a pushing force on the sail.
Whether sailing up wind or down, the boat's performance depends on Sail trim. To achieve correct trim the Sail must be adjusted so it is neither over trimmed or under trimmed. Over trim and under trim are explained here So they can be avoided.
In the illustration the wind is coming directly across the beam. Here the Sails are in too tight resulting in a condition called overtrimmed. The wind is creating a pushing force against the sails but very little lift is created because the air can't flow smoothly across the sail's back side. As a result, the forces tend to heel the boat and push it sideways but do not provide much drive to propel the boat forward.
The sails should be eased out so that the air can travel across both sides of the sail smoothly. Then they will be able to generate lift and the boat will perform properly. The way to find the right trim is to ease the sails until they begin to luff. (The luff or forward part of the sail will start to puffin.) Then trim back in just enough to fill the sails and stop them from luffing.
Another way to correct for an over trimmed situation is to head up. When you get the boat pointed in the right direction, it will accelerate and heel over a bit more. This is due to the increased lift generated by the sails. Correct by heading up if you are beating. If you're reaching in the direction you want to go, ease the sails.
The sails are under trirnmed when they are eased out to far. The sail will luff (flutter) and the boat will slow down, standing up straighter in the water. Here the sails need to be trimmed in, to be filled, in order to get the boat moving. Luffing the sails can be done to slow the boat if desired, but should not be done too much or too long. Sails are damaged by extensive luffing.
- Sailing Trim Guidelines.
- Sailing Upwind: "When in doubt, ease it out."
- Sailing Downwind: "Sails ninety degrees to the wind."
Tacking to Windard (Beating)
The only way a sailboat can reach an upwind destination is through a series of tacks referred to as beating, or beating to weather. Tacking, or coming about, is changing the boat's direction so that the bow comes through the eye of the wind. Since a 45 degrees is about the best a sailboat can point into the wind, tacking requires a turn of about 90 degrees.
Gybing is the maneuver of changing tacks downwind It involves taking the stern of the boat through the eye of the wind. As the boat turns and the stern comes through the eye of the wind, the sails must be brought across to the opposite side of the boat.
Gybing is a maneuver that must be controlled! As the boat is turned, the boom must be controlled as it passes over the boat. If there is more than very little wind, the boom can swing across the boat with tremendous force. Crew members could be injured or the rig could be damaged in an uncontrolled situation. You can prevent mishap simply by pulling in the mainsheet and easing it out again as be boom passes from side to side.
Procedures for Gybing
- Figure 1. When the boat is on a broad reach, (wind off stern quarter) the boat will be turned to where the centerline of the boat will pass through the eye of the wind. The helmsman gives the command: "Prepare to Gybe."
- Figure 2. On that command, both main and jib are sheeted in close to the centerline of the boat.
- Figure 3. As the boat turns further, the wind crosses to the other side. The sails are carefully eased out to their proper position for the new heading in
- Figures 4 and 5. Note: As the boom nears the centerline, the helmsman commands: "Gybe Ho." Ths alerts the crew that the boom will be crossing over. Caution: The sails should be controlled while crossing over the boat. They should not be allowed to swing on their own.