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Monday, January 08, 2007

Aft Floors are IN!

Well, roughed in at least. The new year is off to a good start with the aft floor joists and pads permanently installed.

Referring to the first picture, looking aft, the aftmost is a small 3/4 inch piece of laminated coosa tabbed with two layers of glass. It will mostly be used to support a part of the double berth. Next one forward is the mizzen mast step, more on that later (see below). The next one forward is a floor support and the thrust bearing plate for the Aquadrive. It is two 3/4 pieces of Coosa laminated with three layers of glass. It is tabbed with 4 layers of glass on either side feathering out to 6 inches against the hull. Finally, the last support is in fact the lower portion of the bulkhead separating the engine room from the aft cabin. It is one 1 1/2" piece of coosa laminated in glass.

All floor supports were first tacked in with structural adhesive. All supports were tabbed in using 17oz biaxial glass knitted with chopped strand mat over a 1 inch foam fillet (on the straightmost bits at least, the fillets dont bend very well, even if you saw kerf them).

The pads are 3 layers of glass over shaped closed-cell high-density Airex PVC foam that has been bedded with Corebond.

This last picture is just the temporary work floors laid atop the supports.

What next? Well, in the aft section at least, work can begin on installing upper bulkheads and main cabinetry framing.

A note on the mizzen step

The mizzen step was not glassed in for the following reason: steering. The brand/type of steering system has not been finalized. The current favored system is the Lewmar Mamba Steering System which uses drive tubes, bevel gears and u-joints to connect the wheel to the rudder. This by far is the most flexible installation whilst maintaining strength, wheel feedback and low maintenance. In this installation, such a system would see the drive tubes go underneath the floorboards and through the supports. Cutting holes in place on the smaller supports would be no problem, but the mizzen mast step is 5 inches thick. Cutting holes in place would be quite difficult. So it will remain unglassed until the steering is designed and ready to be installed.

While we are talking steering systems

I will not install a cable/idler steering system of the type that originally came with the Westsail. Too many wires and pulleys. Anyway, I want to keep a nicely designed engine room and the last thing I need is steering cables criss-crossing the space. The Lewmar Mamba system is nice in that the small bevel gears allow a complete 90 degree turn which would otherwise need to be done with large 4 inch idler pulleys (two of them). It would follow the same path, down the centerline aft to the rudder post, as did the original system (sans large idler pulleys). Another thing I like about the Mamba system is that the autopilot drive unit can be attached to any point of the system where there is a bevel gear. So, for the center-cockpit westsail, it could be installed in the engine room, underneath the cockpit floor.

Another possibility is a cable wire system in conduit. Edson and Lewmar have such systems. They allow the wire-in-conduit to make gradual turns without pulleys. On the westsail, such system would see the conduit make a hard turn to port from underneath the pedestal towards the edge of the hull, another hard turn pointing aft, then gradually follow the hull to the rudder post. Such systems are higher maintenance than the Mamba system (conduits must be lubed frequently). Both systems would be easier to install than the original type.