Charbonneau couldn't swim!

Tiller of a sailboat

When Charbonneau, husband of Sacagawea, was at the tiller of the boat during the Lewis and Clark expedition, a strong wind tipped the boat and Charbonneau panicked. He didn't know how to swim! The fiddle player, Pierre Cruzatte (also known as Peter), who was one of the best boatmen of the expedition, had to threaten to shoot Charbonneau to get him to grab the tiller!

Man steering boat using the tiller

As you can see by the above diagram, the tiller controls the rudder which steers the boat.