[Public-List] Dynamic Loads while sailing

[crufone at comcast.net]

Michael, 

Just remember the beam will continue to flex under load.  The reason   
the original adhesive failed is that it brittle brittle and failed   
under the repeated flexing of the beam.  The AL plates will not flex   
making the entire structure very stiff.  Static load flexing   
(flattening you described) is not as much of a concern as the shock   
load flexing.  This dynamic loading of the structure is what causes   
the beam to fail over time.  and unless you have strain gages I don't   
believe you can measure it accurately. 



Larry Morris has got me to thinking with his response above.  Is there any support for the argument to design in some flex in the mast beam as it transfers the load from the mast butt to the hull? I know that structural engineers design in flexible components for tall buildings so that they can resist various wind load conditions.  If the buildings were rigid the wind load would exceed the strength of the materials and the buildings collapse? 

So is there some merit in allowing the mast beam some flex?  I wonder if the mast beam were too rigid  might something else fail? 

I assume while in a strong gust that the rig loads up in some sort of sequence, i.e., sails, running rigging, mast, shrouds, chain plates, couch roof, mast beam , bulkheads, hull, keel.  This might only take part of a second, but it does happen in sequence.  My thought is if each component has some flex or elasticity then the opportunity for the whole to absorb more load is greater. Is this true or am I just out to lunch? 

Michael #133
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