How fast do sailboats go?

If drag could be eliminated, entirely, any sail-powered vessel can travel exactly twice as fast as the wind powering her can blow, while sailing on a beam reach; that is, at right angles to the wind. The best examples of this principle can be seen while ice-boating, when an ice-boat is supported by, and prevents making leeway with, the skates t.hat support her. Many examples of ice-boats travelling very nearly 20 knots East or West, say, in a 10-knot Northerly breeze, and so on, exist.