Not versed very well on engine props. If I cut the other two props to match the broken one will I still have enough thrust to push a 12’ Jon boat? 5 horse engine.

On a larger outboard, I would not do it. On a 5 hp, you may be ok, but I don’t know. I’d opt for a new propeller or get it repaired!

New prop or repair; whichever is cheaper.

What about adding weight to the broken fin till it stops vibrating?(it’s out of balance)

I know you are looking for the least expensive way but a repair or new prop is what needs to be done. Cut those others off and try it if it works I would keep it as a spare only.

That vibration will damage the motor and then it will really cost you.

Marine outfitters sell composite props pretty reasonably. I have replaced many props due to damage done on the Mississippi here in Iowa. On my larger outboards I lean towards stainless steel but on my jon boat with a small outboard I use composite because they last longer due to taking the abuse of striking underwater logs/rocks than the cast aluminum types. I wouldn't mess with your prop for what a composite replacement cost.

Among other things, you will over-rev the engine. Get a new prop.

Thanks all!