I think the term "big boat" might be overstating the situation. The boats that take you from Marina Grande (this is the same port that the ferries from Naples and Sorrento use) are motor boats that hold about 20-25 passengers in an open boat. You than motor part of the way around Capri (15-20 min ride) until you get to an area just outside the Blue Grotto. At that point, passengers are transferred into small row boats that hold about 6, and than the boatman rows you into the Blue Grotto. Of course you do have to pay before you get into the small boat (you have already paid for the larger boat) and than when you come out of the grotto most of the rowers will really pressure you for a nice tip (our guy said we could not get out of the boat until we gave him a tip....only a joke,,,but he did wait for the tips).