Repairing rust and weak holes on a steal boat is a seemingly-constant process. Repairing weak spots or weak holes requires a bit more skill, as it will involve welding and possibly burning, depending on the thickness of the repair material. Both types of repairs will involve painting in one form or another.
Leave a thin film of rust on the metal for the rust converter to adhere to. Apply a generous amount of rust converter, including the areas beyond the edge of the rust. The clear rust converter will turn black when it is completely dry.
Weld the metal patches in place to cover the holes. Inspect for "cold welds" by hitting the weld with a hammer. When the welds are cool to the touch, grind only as needed to achieve a smooth, secure weld.