[Public-List] Lower Mast Plate fastening for non liner hulls

[crufone at comcast.net]

Jeff, 



I have hull #133.  I have not removed the lower mast step plate, but this is my understanding of how it is assembled.  Both the port and starboard bolts of the middle (fore and aft) pair pass thru into the wooden mast beam.  The nuts for these you will find under the bungs on the lower surface of the wooden mast beam. The fore and aft pairs of bolts are only threaded into the upper glass surface of the coach roof.  To me this is the chicken or the egg scenario.  I suspect that the thru bolting to the mast beam was just a production procedure used to help install and properly locate the mast beam.  Because of this thru bolting, the remaining two pairs of bolts are used mainly to position the base plate and help keep it from rotating, thus they only need to penetrate into the glass some 1/2". 



In theory the mast beam functions as an 'I' beam.  The strength of an 'I' beam is created by the web that holds the two horizontal surfaces of the 'I' in alignment.   Bolting the lower mast step plate directly thru the center-line (fore and aft) as well as close to center-line (port to starboard) of this wooden mast beam would, in my book, severely weaken this 'web' and the beams function as a weight bearing 'I' beam. 



In the future I plan to completely remove my mast beam and relaminate it, returning it to the boat in its original form.  I will consider somehow filling in the thru holes on the center pair of mast plate bolts to increase the strength of the  

wooden beam.  It is my thinking that the thru botls provide the possibility of yet another leak into the interior and may NOT be necessary to hold the lower mast plate in location.  I may come up with a solution that has this pair of bolts go into the mast beam but not thru it.  With the additional two pairs of bolts into the glass of the coach roof and something like 4200 sealant or bedding compound I don't think the mast plate will rotate or slide around from its intended location. 



Hope this helps you some with your project. 



Michael 

 1225744557.0