The Navy Department Library's site has an article entitled "Battle of Lake Erie: Building the Fleet in the Wilderness," by Radm. Denys W.Knoll, USN (Ret.). The article pointed out that:
"With the fall of Detroit...The United States had no warships on Lake Erie... . General William Henry Harrison...could not initiate plans to re-take Detroit without naval support."
"President Madison recognized the need for ships, and the necessity of building them on Lake Erie. The capabilities for building ships in the wilderness were reviewed in detail."
See the rest of the article to see why Erie was tapped to build the fleet.