Federal Ship Financing Improvement Act This bill allows the Maritime Administration to guarantee financing (including reimbursement for expenditures previously made) for reconstruction, repair, or similar work in a shipyard located in the United States for, among other things, to change an existing vessel to a vessel of the United States. The bill also requires that certain shipyard modernization and improvement projects financed by the Maritime Administration use American products and materials (i.e., goods mined, produced, or manufactured in the United States).