Sailor Sam's ship The Porpoise is described as a 90-foot long schooner. What is a schooner anyhow? A schooner is a ship with at least two masts, the rear mast being taller or the same height as the other masts. The rear mast supports the main sail. A smaller sail called a foresail would ride on the front mast. From what I have read, I am guessing that a 90-foot ship such as The Porpoise would have just the two masts.
Here are three sites where you can get a good look at various schooners and also get some very interesting information on these ships:
American Schooner Association