Ocean Cruising – The Physics of Sailing

Driving energy of a sailboat is the difference in relative movement of water speed and wind. Wind movement and motion of a boat combine to create airflow. The sail can push your sailboat only in the direction of the wind. You cannot sail in any desired direction.

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<p><strong>Sailing Faster Than the Wind &&num;8211&semi; The Physics of Sailing Explained<&sol;strong><&sol;p>&NewLine;<p>New York &lpar;USA&rpar;&comma; September 02&comma; 2017<&sol;p>&NewLine;<p><strong>The Physics of Sailing<&sol;strong><&sol;p>&NewLine;<p>The driving energy of a sailboat is the difference in relative movement of water speed and wind&period; On a calm day&comma; wind and water current move in the same direction&period; Hence&comma; their relative difference is nil&period; Your sailboat just drifts along on water&period; When there is a relative difference in wind and water current&comma; energy is generated&period; Your sailboat utilizes this energy to sail on the water&period;<&sol;p>&NewLine;<p>The two main components of a sailboat that harness this generated energy are the sails and hull&period; Wind on the sails and resistance of water on the hull together direct your sailboat&period; If wind alone were responsible for sailing a boat&comma; your boat would travel at the same speed as the wind and would be able to go directly downwind only&period; However&comma; this is not the case as often sailboats travel faster than wind speed&period;<&sol;p>&NewLine;<p>Wind movement and motion of a boat combine to create airflow&period; This is apparent wind&period; The sail filled with wind curves&period; The curved surface causes air to flow faster over the surface of the sail&period; This creates aerodynamic lift&period; The hull of a boat resists water force and the keel prevents the boat from being pushed sideways&period; The altogether effect pushes your boat forward&period;<&sol;p>&NewLine;<p>The sail can push your sailboat only in the direction of the wind&period; You cannot sail in any desired direction&period; Sailboats overcome this hurdle by having obstructions under the water&period; These include keel and hull&period; Many often address them as the &OpenCurlyQuote;second sail’&period;<&sol;p>&NewLine;<p>Underwater flow over hull creates a hydrodynamic force&period; This force allows movement of a sailboat in any direction other than straight into the wind&period; The angle of travel of a sailboat fluctuates between 35 degrees to over 80 degrees&period; Therefore&comma; a sailboat can sail directly over 290 degrees of compass after leaving a tacking angle of 35 degrees on either side of wind&period;<&sol;p>&NewLine;<p>A sailboat in motion creates its own apparent wind&period; You can feel this wind onboard&period; When sailing into the wind&comma; apparent wind is greater than the actual wind&period; Hence&comma; direction of apparent wind remains ahead of true wind&period;<&sol;p>&NewLine;<p>As a sailboat surfs forward&comma; proper adjustment of sails generates sufficient aerodynamic lift&period; When your sailboat goes downwind&comma; sails do not generate aerodynamic lift&comma; as airflow is restricted&period; The apparent wind is less than the true wind&period; Together downwind speed remains restricted&period;<&sol;p>&NewLine;<p>Differences in true wind cause differences in apparent wind&period; Sails normally have many twists in their designs to accommodate changes in wind directions&period; Sometimes sails are trimmed because of steep wind gradient&period; However&comma; these factors remain unpredictable and vary according to prevalent weather&period;<&sol;p>&NewLine;<p><strong>Simple Tactics to Sail Faster<&sol;strong><&sol;p>&NewLine;<p>1&period; Tacking is an important tactic to harness wind speed&period; Travel as close to wind direction as possible on one tack and then shift to another tack to go upwind faster&period;<&sol;p>&NewLine;<p>2&period; Reaching or sailing perpendicular to wind direction generates greatest lift in forward direction on sails&period; Although this can cause rolling&comma; turning a boat a little upwind can reduce the rolling effect substantially&period;<&sol;p>&NewLine;<p>3&period; Pull in the main sail and jibe in a controlled manner before turning&period; The main sail opens out slowly on the other side&period;<&sol;p>&NewLine;<p><a href&equals;"http&colon;&sol;&sol;www&period;theteamwork&period;com&sol;ebooks&sol;465-0-guide-sailing-ocean-cruising-medium-sized-yacht&period;html"><strong>Guide to Sailing and Ocean Cruising in a Medium Sized Yacht<&sol;strong><&sol;a><br &sol;>&NewLine;The Complete Reference Guide to Sailing and Ocean Cruising in a Medium Sized Yacht<&sol;p>&NewLine;

Gary Anderson