Designer optimizes racing yacht with Carbon/Balsa design
Reprinted from Composites Technology Magazine - December 2001

When Alan Andrews Yacht Design created a 52 foot racing yacht for the Victoria Racing Team, the goal was a boat with minimal structure weight, allowing the additional keel ballast necessary to optimize sail carrying ability within the Transpac 52 class rules for weight, length and sail area. Builder Dencho Marine of Long Beach California achieved that end using sandwich panels made from carbon fiber fabric and a new lighter balsa core.

Dencho constructed E-glass / vinyl ester open molds for the hull, bulkheads and decks. PAN-based 12K stitched nonwoven carbon fiber fabric (areal weight of 7 oz/yd²) supplied by Anchor Reinforcements of Huntington Beach, California was hand layed in the molds to reinforce the outer sandwich skin. In the hull, up to six plies of 0°/ 90° fabric was layed the length of the boat where extra strength was needed. Unidirectional nonwoven 8 oz/yd² carbon fiber tape was used for buildups at the keel and other stress points. The fabric was wet out with PRO-SET epoxy from Gougeon Brothers Inc. of Bay City Michigan.

Baltek's 4.5 lb./ft ³ density, 1 inch thick Super-Lite end grain balsa core was then layed into the molds and laminated to the skins. Because its epoxy coating prevents resin ingress, Superlite requires less resin than foam core but maintains greater peel strength. At highly loaded hull points, Dencho employed higher density 1 inch thick balsa with compression strength of 355.6 ksi. The inner sandwich skin was layed up as described above. The discrete structures were vacuum-bagged and cured at 160°F for 27 hours in a large portable Dencho-designed oven constructed around the parts.

After cooling and demolding, the boat was assembled, laminated with PRO-SET, then post cured at 160° for an additional 27 hours. Victoria 5 won the 2002 Puerto Vallarta Race and is one of many that Dencho Marine plans to build using the same design and fabrication techniques.