There are many sources of sailing ships suitable for pirate raids, single ship actions, fleet actions or shore attacks. Toys R Us, Playmobil, and CTS all offer suitable items. eBay can be an inexpensive source, especially of the Playmobil ships and sometimes even of the really nice Black Pearl and Queen Anne’s Revenge playsets from Pirates of the Caribbean. The ships can all be further improved with new decks, sails, rigging, etc.
We have articles on how to make sails for your Playmobil ship and computer decking for your MPC pirate ships. I will try to get up as I get a chance.