# finding the centre of effort....help

Discussion in 'Multihulls' started by Gianf1041, Feb 26, 2019.

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### Gianf1041Junior Member

I have a big confusion on my head, I have to calculate the center of effort of the sail plan of a catamaran of about 6 meters that I'm drawing, I'm using different graphic methods but there is not one that corresponds with the other ...... .sic, can you suggest me a resolution of the problem graphically ?? thank you very much for your patience.

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### TANSLSenior Member

Although it is an approximation, usually it is enough to calculate the geometric center of sails.

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### latestarterSenior Member

Could you say what graphical methods you have tried, are the edges of the sails straight or is there significant curve?

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### Gianf1041Junior Member

I have adopted this practical and empirical method.

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### luff tensionJunior Member

Thats cool. What you have actually found there is the Centre of Gravity (COG). The COE would be more accurately found using a CFD on a standard section over a differing range of twist angles.

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### DCockeySenior Member

The term "Center of Effort" is commonly used for the area centroid of the sail plane, which is equivalent to the center of gravity of a cut-out of the sail. It isn't the actual location of where the aerodynamic forces act but is part of the widely used method for "balancing" a sailboat. It's an empirical method disguised with physics terminology but it frequently works.

How would you use CFD results for a sail? Would you substitute the CFD center of pressure for the geometrical centroid in the usual balance methodology?

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### Gianf1041Junior Member

Here is the result with the segment that combines the ce of the main sail and ce of the jib, obtained by tracking the segments of length corresponding to the areas of the mainsail and the jib ............ I think I have solved the my Hamlet doubt. thank you

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