| Some quick calculations suggest a 7.5" mast diameter at the partners, tapering to 6.5" above the hounds for a solid foremast. A solid Sitka spruce stick of these dimensions will weight 214 pounds. A hollow birdsmouth mast with a 20% stave thickness needs to be only 6" and the partners and tapering to 5.5" above the hounds, to be of similar strength. It's weight is about 90 pounds.
Typically the mainmast is of the same dimensions as the necessarily heftier foremast. The fore is the stiffer mast of the two in most cases, as it carries headsails, the foresail and some rigging loads from the main. The same diameters on the main will make a 250 pound solid mast or the same dimensions of the hollow mast will yield a 97 pound stick.
The few hundred pounds of mast weight you save can be equated to about 1.5 tons of additional ballast righting force, which isn't an unsubstantial sum.
The above sticks were calculated to be quite durable and are heavier then they need to be. These would be very close to the dimensions I'd use on a heavy cruiser, which you boat appears to be. If using Douglas fir, add 25% to the mast weights.
The actual dimensions need to be really worked through as part of the rigging, sail plan and mast construction plan process. There's a lot of things I don't know about the design, which can easily affect the dimensions of the masts. No allowance for foot taper has been accounted for, nor has the vessel displacement, righting arm or any of the other typical factors been consider, so these dimensions shouldn't be taken with a grain of salt, but literally the whole salt shaker.  | 
03-03-2009, 07:27 PM
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