With no good choice available for a drop in pre-made holding tank I decided to incorporate one into the hull. After the new ballast cap was laid up (with three layers of biaxial cloth) three layers of biaxial cloth was applied to the hull forming the tank sides. The top and baffle was templated in the usual manner and the parts laid up in the shop and then trimmed to fit. The baffle and the tank fittings were installed, then the top was glassed into place using three layers of biaxial cloth on all seams. West System epoxy was used for the project and the mixture was made slightly resin rich as recommended by West system when building tanks.