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Sunday, October 01, 2006

Main Mast Step Installation

This weekend saw the Westsail's main mast step installed. The masts on W42s are deck stepped, but there is a compression post that sits between the underside of the deck and the keel to distribute compression loads from the mast. This post is typically a length of 2 inch stainless steel tubing. The original W42 plans called for a steel I-Beam about 3 feet in length to be installed underneath the floors. As the W42s were rigged in different configurations, this made it easy to spot the mast forward or aft, depending on the configuration. This hull did come with the beam installed, albeit supported by rotting floor timbers which were torn out (see archives). Since this boat will be a ketch, there is no need for such an I-beam. So, the compression post will be stepped all the way to the keel, but there will need to be some sort of pad to help spread the load. The pad was made from Coosa board. Seven pieces of 3/4" inch coosa were laminated together into a "block" large enough to fit between the two floor timbers where the mast will be stepped. The block is orientated such that the roving in the coosa will be vertical in compression. The underside of the block was cut and shaped to fit the form of the bilge as close as possible, while keeping the topside level and square. For the permanent installation, about 3 quarts of resin was heavily thinkened with milled glass fiber and poured into the bilge. The step was then tapped firmly into the resin and made level and square. The picture shows this installation. The plumb-bob is approximately where the compression post will be. The step still needs to be skinned with glass and accomodations made for limber holes. That is in an upcoming project.