You need to capture a pirate ship; if you stay along the coast, sooner or later one will pop up. I´m not sure which part of the coastline is the best "hunting ground" in this regard, though.

"Fastest" is in this case also "only." And it's probably not fast. But good luck, nonetheless!

Hehe, yeah he's right! If it's quick, then you got lucky (it can happen), as it's basically a "luck of the draw" kinda thing.

I'm pretty sure that if you wait long enough that eventually a ship WILL come, but you may have to wait for a long time for one to sail by hehehe

You can try it--it's not an entirely uncommon thing for players to do. But if you do try that, just be prepared to be sitting there a long while. Maybe make sure you have plenty of food to eat while you wait, and I don't mean just in the game either LOL hehehe

O fictional lead of 1984, you forget to mention the payoff:
Fighting pirates is COOL.

Hehe it IS cool! Yargh! Avast, ye scurvy dogs! Thine vessel are now belong to us! YAAA-ha-ha-HAA!

I always found my best ship hunting ground is the island that Moonglow is on. If you go to the northeast shore, there is plenty of deep and medium water for a ship to get to you. For those that haven't played before, I specifically left out why this is such a good location.

I think, and I could be wrong about this, that getting ships to spawn in Ultima IV works similarly to how it does in the earlier games; that is, the more sea creatures you fight, the better the odds that a ship will appear at some point.

I didn't know people have problems getting ships. I get attacked by pirates all the time!

Well, there aren't that many sea creatures out there to begin with, and fighting them doesn't tend to be that exciting a proposition (no post-battle reward) so if you spend time by the oceanside, and actually seek out sea creatures, eventually the game will tire of sending you Serpents and Giant Squid.
Of course, every so often a pack of Daemons will wing their way out over the ocean. Fun times, that.

Also noteworthy - pirate ships (and dragons, and some other overland creatures) will fire on the party before combat. To avoid taking hits, approach such enemies staying off of straight lines. The enemy has the advantage over you twice - they can fire on the diagonals, and they can move-and-shoot (although they shoot first). If you're at all familiar with chess, try and stay a knight's jump away from pirates until they reach the shore. The range of all overland projectiles is three squares.

Happy hunting!

Thanks for the tips! Very useful stuff.