[Public-List] Dynamic loading on the Alberg

[crufone at comcast.net]

Don Campbell wrote, 
Because the mast base plate is not centered over the mast beam, it 
becomes obvious that the torque on the mast beam is more that we think 
at first glance, even though the force is now spread over the area of 
the mast base plate, most of which is behind the mast beam. That too 
will strain the connective joints of the beam to the hull even under 
static loading. 

Don and Others, 
I really would like to see this point clarified.  On boats that I have observed the mast base plate and the mast butt are centered over the mast beam, both athwartships and fore and aft.  The beam is attached to the main bulkhead by it's forward face using bolts. The aft portion of the mast beam is less substantially supported by pilasters attached to the aft face of the bulkhead.  I assume that this difference in strength of support of the mast beam by the main bulkhead is what causes the torsion action on the mast bean, not the assumption that the mast butt is not centered over the beam. 

On #133 the mast butt is positioned directly over the center of the mast beam below. So on my boat what would cause the mast beam to twist downward on it's aft side if not how it is attached and supported by the bulkhead?  I assume that the strength of tabing to the coach roof is inconsequential. 

It would be good to have this explained to all Alberg owners. 

Michael #133
 1263656681.0