The Great Lakes Intercollegiate Offshore Regatta (GLIOR) was held on Sept. 21 and 22. The course was about two miles east of Navy Pier. There were eight college teams sailing a boat of the same design, the Tartan 10, or its cousin, the LS-10. Northwestern’s club sailing team on the LS-10, M*A*S*H, won first place in this division. Their close competitors were Purdue University, who came in second, and Miami University (Ohio), who won third. The NU team included co-captains Anna Kovacs and Cole Abbott, along with Marguerite Eno, Nick Chesemore, Jackson Adams and Jack Hartfelder. The team practiced several times earlier that week on M*A*S*H, with coaching by the writer, who is the boat owner, and by his son, Ian, who sails on San Francisco Bay. The boat is moored in Chicago’s Montrose Harbor. The practice paid off, as the sailors used the opportunity to learn about the rigging and performance of a 33-foot keel boat. For some of the sailors, this was a new experience, since college sailors normally compete against other teams using a smaller boat with a centerboard. The LS-10 requires a crew of six people, with each person having a specific job. It was the outstanding coordination and teamwork among the sailors that won the regatta.
Competitive sailing at NU is not as well known as some other sports. It does not involve a ball or a racket. It does not involve running or jumping. The challenge for the sailor is to get his or her boat to move through the water using the force of the wind pressing on a sail, faster than that of their competitor. There are many variables that come together for sailing. Of course, wind is essential — it is not possible for a sailboat to move in the absence of wind. Other variables include wind speed and direction, wave direction and height, boat dimensions, including weight of the boat, weight distribution on the boat, sail area, the physics of aerodynamic lift as air flows along the sail and hydrodynamic lift as water flows along the immersed surface of a boat, including the keel.
The wings of an airplane are considered to be a “foil” that generates lift as the plane takes off at a high speed. Likewise, a sail and the keel are also foils. To generate lift, a foil must be positioned in a way that causes pressure on one surface to be less than that on the other, just as with an airplane wing. For this to happen, the foil must slice into the fluid, whether air or water, at an angle, referred to as an angle of attack, which displaces the air more on one side of the foil than on the other. The flow is faster on the surface with the greater displacement of air. It is a principle of physics that the increase in the rate of flow of fluid is accompanied by a lower pressure. The pressure differential between the two surfaces of the foil generates lift. The shape of a foil is key to maximizing lift and minimizing the opposing force, or drag. This may sound complicated — and it is. The design of the foil’s shape involves computational fluid dynamics and testing in wind tunnels or in tanks of water. Of course, it is possible to be a competitive sailor without a deep understanding of the physics of foils.
Other variables that come into play in sailing are the friction of the wind against the land versus the water. Friction against land causes the wind to change direction and to have less speed. Intercollegiate sailboat racing occurs near a coast, such as Lake Michigan or an inland lake, so local factors such as terrain must be understood. It is also important to understand that wind direction and speed are not static but usually change from moment to moment, requiring constant adjustment of the sails. On larger boats, the effect of the height of the mast and sail influence the sailing wind, and wind speed and wind direction may differ between that at the top of the mast versus that at the surface of the water. Other variables include local weather, including the positions of centers of high and low pressure in the atmosphere, since wind flows from high to low pressures.
The most common course configuration for a race is laid out using inflatable marks that must be rounded at the end of one leg of the course before going on to the next leg. The first leg is directly into the wind (windward leg), and the next leg is directly downwind (the leeward leg).
A sailboat cannot sail directly into the wind but must zig-zag back and forth across the direct line to the windward mark at an angle of about 45 degrees. This is called “tacking.” When sailing with the wind coming from behind, it is possible to sail directly to the next mark without tacking.
A 14-foot boat, called a 420, is the most common boat used in intercollegiate competition. It has two sails: a jib attached to the forestay and a mainsail attached to the mast. It is sailed by two people, who work together as a team. A spinnaker is a special sail that is used when sailing with the wind coming from behind and takes the place of the jib. When the wind is coming from ahead, the jib is raised and the spinnaker taken down. In certain wind and wave conditions, the 420 is able to skim the surface (planing) with very little immersion of the hull. The laser is another boat used in competition. It has a single sail and is sailed by one person.
It often happens that while sailing toward a mark, two boats converge. There are rules that specify which boat has right of way. Tactical decisions about changing direction to prevent a collision are based on the Racing Rules of Sailing, and these must be understood by competitive sailors.
Sail racing at NU is a great way to meet people with a similar drive to compete. It fosters camaraderie as well as a respect for the wind and waves on Lake Michigan. Learning about sailing is easily accessible at the NU Sailing Center, which is located directly east of the Segal Visitors Center.
Ronald Kallen is a Feinberg faculty member. He can be contacted at [email protected]. If you would like to respond publicly to this op-ed, send a Letter to the Editor to [email protected]. The views expressed in this piece do not necessarily reflect the views of all staff members of The Daily Northwestern.
