Auxiliary Sailing Endorsement

Captains Marine Online


Welcome to Captains Marine Online.  We are dedicated to providing you with a premier learning opportunity.  It is imperative that you complete all parts of this course as crucial information is contained throughout the curriculum.   Course completion should take approximately 4 hours.  Access to this course will expire one year from the date of enrollment.

Captain Flynn Smith is the narrator for the audio portion of this course.  This audio lecture provides explanations for many important concepts contained in this curriculum.  To begin, find the play button for the audio lecture.  Clicking the button will begin the audio, which will play while you follow along reading the text.  Using the player controls, you may pause the audio at any time or replay a section.  The audio lecture can be reviewed as many times as needed.  Exam questions can be derived from text, audio, videos, and diagrams.  It is important to read and listen to all the content, as well as complete all practical exercises and quizzes.

Syllabus and Course Framework

Time:  4 hours

Lesson Objectives:

  • The learner will be familiar with the principles behind sailing.
  • The learner will know the parts of a sailing vessel, including the standing and running rigging.
  • The learner will know proper sailing maneuvers.

Practical Exercises:

  • Bernoulli’s Principle demonstration
  • Checking sailing equipment to make sure everything is in good working order
  • Practice sailing maneuvers and emergency drills

How a Boat Sails

Factors affecting the movement of a sailboat include the interaction of the vessel with wind and water, specifically with the hull, sails and keel.  Sails extract energy from the flow of air, or wind, by bending it as it goes by.  Likewise, bending the flow of water occurs with the action on the keel.   Sails alone are not sufficient to drive a vessel in any desired direction as the sail alone would push the boat only in the direction of the wind.  Sails (airfoils) and keels (hydrofoils) together allow vessels to move and change direction.  Drag is the backward force affecting the vessel and is caused by friction.

A scientist by the name of Andrew Bernoulli discovered that changing the velocity of air or water brings about a change in the pressure of the air or water.  The faster air or water moves, the lower the pressure.  This pressure would be less than the surrounding air mass or water.  For example, during a hurricane the faster the air moves the lower the air pressure becomes.  A weather forecaster looks at the air pressure readings in a tropical system.  If the air pressure is dropping quickly, the storm is becoming more intense.  An airplane wing is designed with a curved top and flatter bottom.  As the plane increases its speed, the air travels faster over the top of the wing because the distance is longer (curved), creating lower pressure. Force moves from high pressure to low pressure. This is what lifts the airplane off the ground.   While airplanes only utilize air, this principal is applied to the sails (aerodynamic) and keels (hydrodynamic) of sailing vessels.

Practical Exercise:  Hold a piece of paper at the bottom between your thumb and fingers, letting it flop forward.  Blow forcefully over the curved top of the paper and watch the movement of the paper. By blowing across the curved side of the paper you are creating a low pressure area above the paper.  Since the pressure under the paper will be greater, the paper will rise. 

Boats usually sail most efficiently in an upright position so that the aerodynamic and hydrodynamic forces are transferred to forward motion.  However, these same forces try to push the vessel over, called heel. Two ways to counter these forces and keep a sailing vessel from capsizing are weight and width.  As a vessel moves up and down, the extra weight robs the vessel of speed.  A large beam makes the hull harder to push through the water, unless the hull is separated as in a catamaran.

Vessels can actually outsail the wind, or move faster than the actual wind speed.  True wind would be the actual speed and direction of the wind.  Apparent wind is the direction and force of the wind relative to a moving vessel. The direction and speed of a sailing vessel underway can make the apparent wind different than the true wind. A sailing vessel can receive more power from the wind as the vessel picks up speed.  Apparent wind is greatest when the vessel is sailing perpendicular to, or at an angle close to the wind.  When sailing upwind, the sails will have aerodynamic lift.  As a vessel travels downwind, the apparent wind is less than the true wind.

Parts of the Sailing Rig

With few exceptions, a conventional triangle shape is the most popular sail configuration.  The mast is a tall vertical pole that supports the sails. A mainsail is the most important sail raised from the main mast. Larger vessels may have more than one mast, such as the foremast, mainmast, and mizzenmast.  A yard is a spar on a mast from which the sails are set. The luff is the forward edge of a sail.  Most are attached along the length of the boom.  In order to tighten the luff of a sail you would increase tension on the downhaul. Luffing is a sailing maneuver which brings the vessel’s head more into the wind.  Sails are not cut like a flat sheet of paper but are shaped, stitched and patched to provide the best shape under heavy stress, shaking and sunlight.  The largest stress on most sails is along the leech (forward edge) from the clew (lower corner of the sail) to the head (upper portion). Battens provide additional supportat the leech of a mainsail. Sail battens are used to keep the leech extended and prevent sail edge flutter. The boom holds the foot of the sail in place.  The tack portion of the sail is the bottom portion between the mast and boom. The boomvang is a pulley that holds the boom down, while the mainsheet controls the lateral movement of the boom.  The purpose of a vang is to hold down the boom and control slack in the leech.  A cringle is a circular metal or plastic loop used to fasten the corner of a sail.  The bowsprit is a fixed spar projecting from the bow to which the forestays and headstays are fastened.  It is usually angled upward from the horizontal and can also be useful in anchor handling. 

The standing rigging supports the sails, and are generally refers to lines, wires, or rods which are fixed in position while the boat is under sail.  The most common arrangement is a mast supported by stays and shrouds fore and aft.  Stays and shrouds terminate in turnbuckles attached to the eyes of chainplates, which are bolted to the hull.   A forestay is a stay from high on the mast to the foredeck, while the headstay is the outermost stay running from the top of the mast to the bow.  The head is the very top corner of a triangular sail. A backstay is a stay that supports the mast, running from the masthead to the stern.  A temporary repair for a broken forestay can be made by using the jib or main halyard.  Running rigging includes sheets for hoisting and trimming sails.  The proper method to fix running rigging to a cleat would be a round turn and half hitches.  To rig a spinnaker, a sail used in downwind sailing, you would use a foreguy, downhaul, or lift, but not a headstay.  If a fore and aft sail were to tear along the foot boltrope, it could still be flown by taking the first reef.  If you were running before the wind a boom may be prevented from accidentally jibing by using a lazy guy.  Hanks are the metal horseshoe-shaped pieces used to bend a staysail. A preventer prevents the boom from jibing and is run from a point on the boom to a point forward such as a deck cleat.  Reef lines are used to tie off excess sail when sails are shortened, or reefed.  A Cunningham is a line that controls the tension along the luff.  A topping lift holds up the free end of a boom when the sail is lowered.  Chafing gear is used to prevent chafing or wear on the line caused by lines rubbing.

A vessel may carry sails of different sizes and weights to suit different conditions of wind or point of sail.  Of the four jibs, only one would be used at a time. The genoa is an overlapping jib. The storm jib is the smallest sail and is made with the heaviest material to withstand strong winds.  The mizzen  is the aftermost mast and sail.   A halyard, outhaul, or sheet can be used in handling a jib or stay sail (not a downhaul). 

halyard is a line used to hoist a spar or sail aloft.  An outhaul is a line or gear used to tighten or adjust the foot of a sail on a boom.  A sheet is used to control a sail’s lateral movement.  A downhaul is a rigging line used to hold down a spar or sail.  Twisting of the mainsail can best be controlled by increasing tension on the vang. 

The hull of a sailboat is very different than any other hull in its need for a large surface for lateral resistance.  The hull must redirect the sideways force of the wind into forward motion of the vessel.  This can be done on smaller vessels by extending a centerboard or daggerboard down into the water and securing it there.  A centerboard is a thin plate that can be swung down through the keel to increase the lateral area, but can be retracted to lessen the boat’s draft.  When sailing on tack, the centerboard is used to reduce side slip of the vessel downward.  When sailing with the wind from dead astern, the main advantage of a centerboard is to aid in steering.

Block and tackle systems are common on sailing vessels.  Lines are run through sheaves in the blocks that make up the tackle to give mechanical advantage to the load being lifted.  Generally the more sheaves used in the system the greater the mechanical advantage.

Practical Exercise:  On your own sailing vessel or one that is available to you, check your jack lines, life lines and harnesses for wear and tear.  Check drogues, warps or sea anchors for wear.  Check your foul weather gear and make sure that it is properly labeled.  Check your reefing lines, stays and shrouds for excess wear.  Mark your jib car leads at 5 knot increments.  Check your electronic instrumentation, anti-syphon valves, fire extinguishers, and other safety equipment to make sure that it is all in proper working order.

Sailing Maneuvers

Sail Trim

If sails are trimmed properly, the course that will normally result in the greatest sailing speed would be the course with the wind off either quarter.  When steering a sailboat, the direction of the wind determines the method of changing directions.  The relationship between the vessel’s heading and the direction of the wind has a set of standard names and is called The Points of Sail.  They include: Into the wind, Close-hauled, Beam reach, Broad reach, and Run.

It is an important safety aspect of sailing to adjust the amount of sail to suit the wind conditions. As the wind increases, the amount of sail should be reduced. Reefing means reducing the area of a sail without changing the sail out for a smaller one.

Telltales are wind direction indicators that are mounted on the rigging. Since wind can’t be seen, telltales reveal the actions of the wind. These can be yarn, ribbon, or pieces of cloth. It is best not to place telltales near seams as they can get caught on the seams.

Heading up (luffing) means steering so the wind is coming from directly in front, or closer. This requires trimming the sails. Heading up so the wind is directly ahead causes sails to luff, or flutter. A vessel is said to be in irons if it loses maneuverability due to luffing. Tacking, or coming about, is one of the basic turning techniques where the direction of the vessel is changed by using the rigging so that the wind comes from the other side of the vessel. A sailing vessel with the wind coming over the port side is said to be on port tack. Conversely, a sailing vessel with the wind coming over the starboard side is said to be on a starboard tack. A reaching course is one in which the wind comes over an area extending from the bow to the quarter. If a vessel is sailing on a close reach and a strong wind heels the vessel hard over to one side, you can reduce the heeling yet maintain your speed by easing the mainsheet and bear more away from the wind. With sails properly trimmed while on a reaching course you change to a close-hauled course. This will cause a greater heeling force to leeward and a decrease of speed. It will require you to sheet-in to maintain sailing force forward. Running is sailing the vessel within 30 degrees of either side of dead downwind. A method by which you can temporarily slow or stop a vessel is to bring the vessel’s head into the wind and let the sails luff. When shifting to a course where the wind comes more from astern, easing the main outhaul would allow the sail to catch more wind.

In a storm use Engines

Heading down means steering so that the wind is closer to the vessel’s aft. Sails would be eased, or let out. Jibing is a turning maneuver where the wind comes on a different quarter and the boom swings over to the opposite side. An accidental jibe can be dangerous to anyone in the way when the boom swings.

Trim is the fore and aft balance of the vessel on an even keel. This can be accomplished by moving ballast or crew.

Spinnakers allow sailors to achieve maximum speed when sailing off the wind. These work like a kite or a chute and are often called flying sails.

Always pick the most advantageous route.

Practice docking a sail boat under sail under ideal conditions.

“Watch the video on Heavy Weather Sailing as exam questions may come from this video. When sailing in heavy weather, a sea anchor or drogue may be used. A sea anchor is put over the bow to hold your relative position in severe weather. A drogue is put out over the stern to prevent surfing down a wave (yaw) and return control to the rudder.”

Heavy Weather Sailing Part 1

Heavy Weather Sailing Part 2

Heavy Weather Sailing Part 3

Practical Exercise:  Using your own sailing vessel or one that is available to you, practice maneuvers such as Man Overboard Drill and docking under sail alone.  Practice towing a drogue in a following sea to reduce yawing.  Practicing maneuvers under calm conditions will help you prepare for maneuvering in tough conditions.