Frigates have been a part of the series since Ultima I, but only starting with Ultima V was it possible to buy them (before, they could only be captured from pirates). This was also the first time that skiffs were supplied with a frigate. By the time of Ultima VI, skiffs were not standard fare on the frigates, but they had gained the ability to sail everywhere.
Frigates were seen no more after that time, due to engine limitations reducing ships to simpler design. However, the intro to Ultima VII Part Two shows that actually the Avatar's ship is supposed to be a frigate.
When a frigate docks near you, you can commandeer it - if the crew will accept you as a seasoned sailor. Otherwise, they'll turn the broadsides on you.
Ships are very scarce. The Pirate fleet has sunk most of the regular ships. When thou hast a ship, thou needst to maneuver it. To sail a ship, one must learn the ways of the winds. Thy ship may not sail against a wind, but must tack around it. Watch out for sudden shifts in the wind for the wind is a fickle elemental force.
Visiting island communities requires travel by ship. Despite rather outlandish rumors of people wandering the heavens in great airships, sailing on water is the fastest and most popular long-distance mode of transportation there is. The most common watercraft on the ocean are frigates. Tall, stately three-masters, the frigates cut through seas swiftly and smoothly. They generally have a two-level open deck and a below-deck with a forward cabin, rear bunkroom, and centre cargo hold. Most ocean going frigates are built to accommodate heavy cannons for broadside fighting and have two gangplank gateways on each side.
Several of the port towns along the shores of Britannia boast ofcraftsmen renowned for their dedication to the construction of safe, dependable sea vessels. Whether you need a small skiff to get upriver, or a mighty sailing vessel for open sea travel, the local shipwrights will be more than happy to discuss terms. It is wise to pay attention to information about local sea and wind conditions before setting out in a new craft.