I believe the Model 401 is a battery ignition.
The Seaking Model 400 had a magneto as well
as not having the anti-cav plate that Tom has
pointed out. If it should be a Model 400 the
underwater exhaust would be from another
motor as pm-t2 has mentioned. Not sure if
the tiller is correct on this example pictured.
More pictures may be helpful in discovering
what you have.
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.