Preparing New Fiberglass Backing Plates

The replacement backing plates will no longer be balsa and plywood. I purchased two 12" square 1/2" fiberglass sheets and cut them so they can be inserted as core replacement in the areas where the rudder gudgeons, chainplate and swim ladder are mounted. This serves to isolate the balsa from the bolt holes, provides additional strength, and prevents the bolts from compressing the balsa. The picture below shows the pre-staged pieces ready to be laminated. The buildup includes 3 layers of 17 oz biaxial fabric so the final thickness is the same as the core.


This photo shows the assemblies after the glass was laid up with resin and cured. The pieces were covered with plastic and a board with weights to obtain a reasonably flat surface.


The picture below shows the pieces after the resin cured. The edges will be trimmed, the pieces sanded for bonding, and the hole pattern drilled prior to bonding to the transom. The fasteners will be waxed to hold these pieces in place while the core-bond cures.

Start Transom Reglass, Cut open stbd aft

The prep work on the transom is finally complete. There was a mixture of resin and wet plywood at the base of the rudder mount that was a real pain to chip out. Once the grinding of old material was complete, the areas was sanded, vacuumed, and wiped down with acetone... all while hanging upside down through the cockpit lockers. The picture below shows the transom with two layers of 17oz biaxial fabric glassed in.

I'll be using a product called "core-bond" to attached the core to the fiberglass. I didn't have it this weekend so instead installing the new balsa, I started cutting into the stbd side to recore selected areas. Below is the area just forward of the transom. The was rotten for about 18 inches forward. The core in other places was solid but soaked. This was difficult to remove so I decided to cut around the solid areas and will open it up to dry it out.


The photo below shows the upper area of the stbd side all prepped and ready for glass. I left a small border between the transom and the edge so I have a structure to fill with thickened epoxy to isolate the transom from the rest of the boat.

Below show where I cut around solid core. You can also see light areas at the bottom. This is where I ground the blisters on the outside of the hull.