1967 Johnson 20HP Outboard Shifting Problem

I have a 1965 12 foot feathercraft powered by a 1967 Johnson 20HP electric start outboard. Took the boat out fishing yesterday and the motor started and shifted into
forward with no problems. I let it warm up at about 1/4 speed as we pulled away from the dock for about 2 minutes. We got out into the main lake and I opened up the throttle to about 3/4 and the motor seemed to be running fine. Suddenly the motor revved up and the boat immediately slowed down as if it slipped out of gear. We limped back to the dock going about 2 mph. I'm hoping my explanation of the problem is sufficient that someone might be able to tell me what the problem is and how much it might cost to fix it. Any help would be appreciated.

Re: 1967 Johnson 20HP Outboard Shifting Problem

Sounds like a spun hub in the prop.Pull the prop and put a waterproof line across the hub test the boat and check the line.It will likely be broken.
A prop shop can rehub the prop.If the prop is badly worn you may want to replace it.
At that age it could actually be worn undersize.

Re: 1967 Johnson 20HP Outboard Shifting Problem

Sounds like you spun the hub in your prop, might check the drive pin also.

Re: 1967 Johnson 20HP Outboard Shifting Problem

Thanks to both of you for helping me out. I'll check it out and report what I find.