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Friday, March 15, 2013

Main Compression Post

This piece had been blocking progress on the forward salon flooring. This is a 3-inch diameter heavy gauge polished stainless steel post that sits between the deck and keel. The purpose is to bear the compression loads from the main mast directly above.
Under the floor: keel step pad center-above.
Most (all?) Westsail 42's have a three foot steel I-beam under the floor on which the post rested. With this I-beam, the post could be spotted more forward or aft to adapt to the rig configuration/sail plan (sloop, yawl, ketch, etc.). Since we are planning a ketch, such heavy I-beam is not needed. Instead, the post leads straight down to the keel atop a specially made five inch wide pad. The pad is six layers of coosa board laminated with glass in between. All fibers are oriented vertically.
Base of the post: floor beam support, wire chase slot, lag screws.
The post also has attachments for the center beams supporting the floor. Two pieces of angle are tabbed to the sides with ends of the support beams thru-bolted to the tabs. A slot has been cut in the post, below floor level, as an exit for the mast wiring (spreader/nav lights, VHF antenna, etc). The post is held in place with four half-inch lag screws on both ends.
Floor (unfinished) in place.
The attentive reader will note that, with the installation of this post, we have decided to go with a deck stepped rig. We were undecided and had been leaning toward a keel stepped mast (mast goes through the deck down to the keel, no compression post needed). However, we reasoned that a keel stepped mast, though stronger (the deck provides an extra moment of stiffness), would be quite annoying with a huge mast in the middle of the forward salon.  Also, deck stepped makes for an easier rig installation.
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