It’s worth noting that not only are there many countries out there with navies, and even growing, modernizing navies (Iran and China are in a naval arms race at the moment, with both developing submarines, aircraft carriers, and various smaller combatants), but many of those navies have submarines that are damned difficult for our own submarines to detect and sneak up on.
American naval doctrine generally calls for very long-legged ships, which means we have nuclear submarines, but not diesel subs (diesels have shorter range because, well, they CAN run out of fuel in less than 20 years, and thus require refueling relatively often). The thing is, Diesel subs are VERY sneaky. Much quieter than a Nuke sub, as in, it’s possible that they might hear our sub before our sub knows it needs to be listening for theirs (to be fair, our sonar and audio listening tech is probably a good bit better than those of many third world nations). The Euros have some very fancy stuff, including diesel submarines that don’t need surface air to run their diesels. The US Navy currently includes one Swedish submarine, along with it’s Swedish crew and officers, which is being leased to us in order to help us develop doctrines and techniques for dealing with these guys.
And as for piracy existing only in faraway places, and not in our own backyard. How far away is the Carribean from the US? Here’s a tip, stand on the beach in Puerto Rico and spit really hard into the sea breeze. Hell, give a rock a really good throw from Miami, if you want to inform my various Puerto Rican friends that they aren’t American. Aside from that, piracy generally exists where there are lots of ships to be pirated, which is in bottlenecks in less civilized areas. The US depends on a great deal of overseas trade, thus our merchant ships often find themselves in these waters as a matter of financial necessity. You would have us depend on the incompetent and possibly corrupt goofs in the navies of such highly developed nations as Somalia?
And yeah, modern surface combatant ships are designed to engage enemies many many miles away, theoretically the Ticonderoga cruisers could attack an enemy ship from 100+ miles away with a Tomahawk if it felt so inclined (and assuming it has a means of targeting said ship, which could be done with reconnisance planes, helicoptors, or maybe even satelites if they know where to look for the enemy ship).
Plus, I know a few guys in the Navy. If you get rid of the navy, you give all those guys nothing to do but hang around HERE :eek: . Trust me, this is a poorly thought out idea. 
