Dont' forget that the blocking should be both hollow and tapered— a hollow (but very nearly solid) octagon. The taper should be on the inside of the octagonal plug.
You want the taper so as to not induce a hard spot in the finished spar; you want the inside hollow so as to allow the spar to drain. Without the hollow, any water that gets into the spar via holes for wire, fittings, halyards, fasteners, etc., ...or just getting in from the top of the spar, will wind up sitting on top of the blocking.
It will eventually rot.
You can imagine what happens next.
Boys, ya know... [this just occurred to me]
You could, if you planned it properly, engineer the blocking into the birdsmouth staves themselves— a gradual 'swelling' of the wall thickness where the blocking is required.
Or make the staves for the blocking and glue them into place on each birdsmouth staves prior to gluing up the birdsmouth.
[ 08-04-2003, 01:10 PM: Message edited by: Nicholas Carey ]
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