Just to add in my own take on the 'fastest ship' discussion.

How fast a paticular ship is can have a lot to do with the situation In extremely choppy seas smaller boats tend to get thrown around by the waves and will not be as fast as larger ships, even if they are in calmer waters.

In shallow waters ships with a flat bottom will be able to sail faster because they can ignore sand bars and reefs that would ground or destroy ships with a deeper draught (how far the bottom of the ship extends underwater).

When there is no wind the fastest ships will be the oar powered ships. Galleys, Xebecs, and ships small enough to be rowed will all be able to outpace ships that rely on sails in these conditions. Later on we will see steamships appear which could also move when the wind was lacking.

Steamships also have the advantage of being able to ignore wind direction and make decend headway even against the wind, this gives them an advantage in speed when heading close the wind.

Ships with lateen (triangular) sails will also be able to head closer into the wind than square rigged ships. Ships with square sails would have to tack in order to keep up with a lateen ship.

In addition to this the current condition of a ships sails, the size of its crew, the cargo it is carrying and the number of barnacles on the hull (honestly, it can make a difference) can all affect the speed of a ship.