When did William Clark start to sail?

Answer 1

William Clark did not "sail" per say. But he did journey through the Louisiana Territory on rivers with Meriwether Lewis and other members of the Corps of Discovery.

Before Lewis met up with Clark, he began the expedition on August 30, 1803 in Pittsburgh PA. Lt. William Clark would offer to join Lewis on the expedition weeks later on October 13, 1803 at Camp Dubois (in present-day Indiana). There they named their team the 'Corps of Discovery'. At the time, Lewis as 29 years old and Clark was 33. From there, they sailed down the Ohio River towards St. Louis.