Getting the plug fair and airtight is crucial to the vacuum bagging of the diagonal skins. I wonder what they used for a resin? They put down a lot of skin panels before they bag so the resin has to have a long working time, but I don't see anything that looks like heat to do the final cure? I was involved with a 39' custom (epoxy glass over corecell) and used a slow cure resin so we could do the layup and get the bag on before the resin went b-stage, but then the whole layup was cured at 140F to do the final cure.