📝 Miss Katherine Tugboat seen in boatyard, Mahone Bay, N.S. Canada
2 months ago
Hi Ron - alternatively to JBs suggestion you could try two other things . Use a 4mm Brass nut (assuming its a 4mm shaft) then file that to almost washer size - but ensure there's still a little bit of thread left - that will still work as a locknut - use a file BOTH sides to ensure that - there is also some stuff out there ( non-permanent threadlock ) which you can use in addition to keep the prop from falling off. Secondly file away the front face of the rear propshaft bearing - again to washer thickness - just enough to keep it from pushing into the tube . They are usually a very tight tapered fit in any event and unlikely to go further into the tube even if you filed of a little too much - assuming its a bronze/brass bearing. a nylon one can also be filed - but not as thin as metal.
From experience I have removed the tip of a prop altogether for a similar reason (look at outboards) and its still a very fast little boat without much noticeable cavitation . However in this case agree with you that the blades themselves might pose a problem . I would personally remove the tip completely - leaving a flat face on the boss.
Hope that helps