Raft

A raft is a flat-bodied water vessel which lacks a hull.

Description
Rarely used by any who can afford better accommodations, rafts were first encountered in the days of, where they served as a sort of poor man's frigate; a cheap solution for anyone needing to cross bodies of water. However, these rafts possessed no on-board armaments, and waterborne adventurers riding them had to rely on their own hand-held weapons -- preferably ranged ones -- for protection at sea. In this era, these crafts were available at transportation shops in most coastal cities in Sosaria.

During the rise of Exodus, most merchant vessels were sunk by by a pirate fleet, and rafts became unavailable to the Sosarian and later  Britannian populaces, with captured pirate vessels being the only means for sea travel for many years. Even after the resurgence of shipwrights around the time of Blackthorn's brief reign,  skiffs proved a more popular light water vessel, although rafts briefly made a reappearance in the days of  - still unarmed, but capable of accommodating a full party's worth of passengers.

Rafts in Eodon
In the hidden valley of Eodon, the tribal peoples of the area employ rafts for water transport - making use of large, multi-passenger vessels requiring at least four individuals to man the paddles which propel them. Two such crafts could be found in the valley during the Avatar's adventures there in Savage Empire: one to the northeast of the Pindiro village (unfortunately unequipped with the necessary paddles during the time of the hero's journeys); and one on the lake to the west of the  Barako village, which was necessary for passage to the island home of  Topuru, former shaman of the  Urali people.

Ice Raft on Serpent Isle
On the Serpent Isle, the Avatar would be forced in Ultima VII Part Two to navigate the treacherous northern ocean on an ice raft in order to reach Penguin Island, the Gwani Death Temple and the Ice Dragon's Lair. While the ice raft looked like a simple slab of ice, it was fully manouverable and the only way to navigate the partially frozen northern seas.

Trivia

 * Using a raft in Ultima VI is not recommended. The raft is completely dependent on the currents and with bad luck - which can come easily - the raft will be pushed against the edge of the world, forcing a reload or quitting the game. A skiff is a much better choice.