I am often asked how we treat through hulls with hull coring. You see, the old, less than stellar reputation that balsa cored hulls had was often the result of the way less conscientious builders managed through hulls. We have always removed core in zones where through hulls are going to penetrate the laminate but like all things quality it takes a little more time and effort. Here's an example of the Sabre 40 hull laminate where Airex PVC foam core has been removed to provide a solid glass zone for installation of raw water intakes.
This image was taken prior to the fiberglass stack being added to the inside of the Airex PVC foam core. Foam cored hulls provide the best structural ccharacteristics while lowering overall part weight. For the consumer that means lower fuel costs.