So, a galleon is 160 feet long, and 33' beam. Rendered as a cylinder, 137,000 cubic feet. We'll call that good enough, because while a galleon has a lot of empty space, it's also got some masts, which are tall and solid.
A branch we will define as a cylinder about 6' long and a 6 inches around, which means its about 1.18 cubic feet. Thus, you need about 116,000 units of reagents, not including the 11,000 square feet of sail.