Great MOC!
To answer your question about why sweeps (oars) were used with this ship is mostly to do with location. The lower Great Lakes (Erie and Ontario) are traditionally much calmer waters than you would typically find in an ocean. It is quite common for wind to die down completely on these lakes, leaving sailing ships becalmed. There are a few instances of sweeps (oars) being used during battles, chases or pursuits in lake engagements during the War of 1812. Generally, sweeps were very much an auxiliary source of propulsion; Sails were predominantly used.
