Date: 5/23/2006
Name: Darren
email: dgfinck@yahoo.com>
subject:re: replacement mast for SJ 21, 1979
I have collected the following specs for the mast cross-section. It's not just a round pole, so it doesn't have a "diameter," per se. It's an aluminum extrusion. I don't know who made them for Clark, but the cross-sections from a variety of suppliers appear very similar to the masts on the two SJ21s I've owned:Mast cross-section: 2.75"x3.75"x0.100" 6063-T6
... Dwyer DM-375, Kenyon "D", Spartan CD-5
... approximate weight: 1.14-1.30 lb/ft
... Ixx = 0.59-0.63 in^4
... Iyy = 1.50-1.52 in^4http://www.dwyermast.com/items.asp?cat1ID=20&cat1Name=Masts&familyID=38&familyName=DM%2D375+Mast
http://www.rigrite.com/Spars/Kenyon_Spars/D-boom.html
http://www.rigrite.com/Spars/Spartan_Spars/cd2_mast.html
Somewhere I've got the overall mast length, the location of the spreaders, and the location of the forestay attachment (it's a fractional rig).
df
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