San Cristobal Boat Works

Coastal, Lake and River Adventure Rowing Skiffs

The making of the new hull mold

The original hull and deck molds from the first generation builds were stored in a back yard. They had been subjected to heat and cold cycles and standing water. This had damaged the finish and caused some warping.

There were originally two molds. One for the hull and another for decks, gunwales, and seats. The generation 1 build process used lots of labor, filling and fairing to complete a skiff. We have eliminated the “parts and pieces” mold and will be molding in variable shaped core as part of our infusion build process. Separate table top molds, 3d printing and CNC machining will be used to build decks, seats, and other fittings.

After building the prototype and working though what our future clean build process would require, we decided to build a new master “plug” using the old mold as the starting point. Below is the visual story (in reverse chronological order) of how this was accomplished:

New Mold after pulling from plug and flipping over
The almost 500 pound hull mold being pulled from the plug
Cradle support structure and reinforcements are designed to prevent warping and eliminate pressure points that could show up in finished part
New mold on top of plug before any support structure added
Spraying tooling gel coat on the polished and waxed plug. This layer will become the surface of the new mold
Polishing the new plug to a Class A finish
The 19 easy steps of plug surfacing and materials used.
Markup to show where to remove material in just one of the many grinding and fairing iterations to remove defects that were transferred to the new plug from the original mold.
Templates and a laser level are used to identify defects in the new master plug.
Pulling the new plug from the old hull mold
The new plug with reinforcements and bulkheads complete.
The new plug layup complete
The original modified mold with freshly sprayed gelcoat that will become the outer layer of the new plug.
The original mold with gunwale modifications and vacuum bagging flange structures added
Forming up changes to the original mold
The original hull molds from the generation 1 production