CHAPTER 4 BOAT BALANCE


Center of Lateral Resistance Center of Lateral Resistance is the focal point of all the forces resisting slipping sideways through the water.


Center of Effort is the theoretical focal point of the force generated by the wind acting on the sail(s).


Drag is a slowing force resulting from the friction of a boat moving through the water.


Center of Effort


Center of Lateral Resistance


HOW SAILS AND FOILS WORK TOGETHER When the lift generated by the sails is combined with the lift of the underwater foils, the resultant force moves the boat straight ahead. (In actuality, a sailboat always goes just a tad sideways.) When the underwater foils are not optimized and made fair and smooth, the flow of water is disturbed and the foils develop drag through the water. This drag reduces the amount of lift and the boat slips more to leeward.


You can steer a boat with its sails, crew weight or rudder—or a combination of these—because of a principle called balance. A sailboat is a collection of forces in motion, not all of which are headed in the same direction. There are forces exerted by the mainsail and the jib, both of which pull the boat forward and sideways; the location of this collective force is referred to as Center of Effort. There are opposing forces exerted by the water on the keel and rudder, and the location of this collective force is referred to as Center of Lateral Resistance.


When all of these forces are in balance, the boat will sail forward in a straight line. If they are not, the boat will want to turn.


24 Table of Contents


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