Hola

Here is the problem: I own OS46 with 11/8 prop and 2.5 spinner. Run it about a dozen times without problems, tonight i tried to crank it up as always with electrical starter and for no reason my propeller nut come off. I tryed to tie it as best as i could but no resolts. At this point I am desperate and will try any suggestion. Thank you.

There is a couple of ways around that.
a double nut available 1/4"-28 that
binds inside the first nut. Look for four-stroke type
prop nuts. Two pieces and won't back off.
Don't break the shaft but do tighten those prop nuts
good

Sounds like a great idea Bumstead, gona get on it first thing in the morning. Thanks a lot for the hint.