February 11, 2019
I picked back up on the core work today, and meant to finish out the glassing in of the old icebox; however, as the work progressed, I decided to hold back laying down the top skin today and focused just on installation of the new core. With a sheet of plastic, I templated the two layers of 1708 biaxial that would form the top skin, and I also created the template for the new core material.
Back in the shop, I used the templates to cut out the 1708 biaxial that would form the top skin and the balsa core. I elected to prepare the balsa core as two pieces due to some irregular shapes in the perimeter area of the old icebox access hatch - making installation a bit easier.
I painted out the underside of the new core pieces as well as the bottom skin. Next, I mixed a pot of epoxy thickened with a combination of West System's 406 colloidal silica and 407 low-density. I then troweled the thickened epoxy mixture onto the bottom skin and firmly pressed the new core material into position. I cleaned up the squeeze out with a squeegee, ensuring that all voids were filled with the epoxy mixture.
Since I decided to lay up the top skin in another work session, I applied some peel ply around the perimeter to eliminate the need for water-washing and sanding the cured epoxy.
With the larger cockpit work at a point where I felt good about it, I decided to move into the cabin to apply core to the aft bulkhead of the coach roof. I needed to add some thickness, or dimension, to the aft bulkhead of the cabin which would provide better support to the companionway trim; beefing up this bulkhead would also improve the mounting of any sailing instruments the owner may elect to add in the future. I began by templating the starboard side of the bulkhead in my usual way - using plastic sheeting. I created a template for the single layer of 1708 biaxial I would lay over the core material. I also created a template for the balsa core.
I repeated this exercise for the port side of the bulkhead. The existing hole in the bulkhead was from a previously mounted bulkhead compass, and I would enclose this hole with layers of 1708 biaxial from the exterior face of the bulkhead...a blank canvass for the owner is a good place to start.
I brought the templates back to the shop, laid them out, and made relief cuts in the templates to allow them to lay flat.
I then offered up the templates to the large roll of 1708 biaxial, and removed the two sheets of fiberglass (one each for the port and starboard side). I then altered the templates and used them to remove the new 3/8" balsa core.
Like the old icebox, today I would just be installing the new balsa core on the cabin's aft bulkhead. I mixed a small pot of epoxy resin, and painted out both balsa core pieces as well as the surface of the existing bulkhead in the cabin. I then mixed a pot of thickened epoxy, and troweled it onto the vertical surface of the starboard side aft bulkhead in the cabin.
Just prior to the prepping the surface of the bulkheads, I prepared braces and support panels to keep everything in place while the epoxy cured. I also grabbed a few clamps and made up a support panel to ensure good adhesion and consistent adhesion. I placed the new balsa core panel onto bulkhead, and firmly pressed it into the troweled thickened epoxy. I then carefully mounted the clamps and support braces. Finally, I cleaned up the squeeze out epoxy as a move to minimize future prep work for the layer of 1708 biaxial fiberglass.
I repeated the process described for the starboard side of the bulkhead on the port side of the bulkhead. The portion of the bulkhead between the work area described today would also receive balsa core and fiberglass, but would be done at a later time.
On the exterior of the aft bulkhead, on the port side, I applied a layer of thickened epoxy bringing the surface to fair with the surrounding tapered bulkhead. I placed a sheet of peel ply onto the thickened epoxy to ready myself for layer(s) of 1708 to fill this old bulkhead mounted compass hole. With that, I cleaned up and closed the shop for the day.
Total Time Today: 5 hrs
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