Buck, your knocker should make contact with
the end of the crankshaft putting the impact of
the blows there. If it doesn’t then your putting
the impact on the crankshaft threads which
could distort them. If your knocker is in fact
making contact with the end of the crankshaft
ignore this response.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.