There are some important terms in sailing that you would need to know. The terms I will explain are the parts of the sail and boat, some forces, and aerofoils. Some of these terms are simple while others are more complex. On a triangular sail the tack is the front bottom corner of the sail; it is called the tack because when you tack, or your front crosses the wind it is the first part to switch over. The luff is the entire front edge, when you tack it is the part that luffs or flaps first. The leach is the back edge of the sail. A sail is not flat while it is sailing, it has a curve called the camber. The hull is the main body of the boat. The keel is a large, heavy, hydrodynamically shaped plate protruding from the bottom of the hull.
Some terms that describe forces need to be known to under stand most of this project. These terms are lift, drag, turbulence, aerodynamic, and hydrodynamic. Lift is what allows a boat to sail up wind; it is described by Bernoulli’s principal. The Bernoulli principal says that a fluid that is moving fast has low pressure, and a slow moving fluid has high pressure. When there is a pressure difference there is always a movement from high to low pressure. Drag is self-explanatory, when there is something that is solid moving through a fluid, then the solid drags causing drag. Turbulence is a form of drag; it is fluid that is spinning after it “falls” off the object. When something is aerodynamic or hydrodynamic it means that it travels well in the certain fluid, for aerodynamic the fluid is air, and hydrodynamic the fluid is water.
The last word is aerofoil, an aerofoil is a neat shape that is made when sails are filled with wind, and they are also the shape of airplane wings. The shape is curved in the front area, while the other side is a shorter distance. This shape allows Bernoulli’s principle to work since you have the air on top going faster than the air on the bottom. This shape is used in many other places to, to either bring things up or push them down.
A sail pushes not only forward but also a bit towards the side. If it was just a boat with no keel or something in that place then it would just fall over. The keel is a hydrofoil and is put there to give resistance against the sideways force that comes from the sail. The keel causes resistance as well as drag, and the sail gives off force and drag as well. When the resulting forces are even then the boat moves forward since all the sideways motion is eliminated.
There are a few groups who are doing research on sailing, and improving the sails. Two of these groups are the Yacht Research Unit at Auckland University in New Zealand, and the Stanford Yacht Research group at Stanford University in the United States of America.
The Yacht Research Unit in Auckland is part of the Mechanical Engineering sector of the university. The Stanford Yacht Research group at Stanford has people from the School of Engineering, and the School of Earth Sciences. These groups have aims that you can view from their home pages.
There are a few goals in sail development that are common to most research groups. These days to make a sail they can do some of the calculations on computer, but the rest must be done by building a prototype and testing it in a wind tunnel, this costs a lot, and the sail gets trashed so they are trying to develop a way to get all the results without a prototype. These days, upwind sailing is more understood than downwind, so a lot of research is placed on how to optimize that sector of sailing.
Upwind is considered to be more known than downwind sailing. Research groups are trying to optimize sailing downwind by modifying the sails. There aren’t as many research projects happening on upwind sailing, as there are on downwind. Downwind there is a third sail that is introduced, which makes it even more complicated, this sail is the spinnaker. The spinnaker comes in many different shapes but the idea is always the same, the spinnaker is a bag that catches the wind and helps push the boat downwind faster.