Two spun props in two weeks why?

[canemode]

Hi, I took my boat out two weeks ago and was running for about 10 minutes when my prop spun and I had to idle it home again. I borrowed a mates prop for the same motor (Johnson 50 2 stroke 1998 Outboard) and after 20 minutes driving the same thing. This must be more than a coincidense, something else must be causing this. Does anyone know of anything that can cause a prob to slip other than impact. I definately have not hit anything on either outing. My mates prop was older than mine, but its seems to much of a coincidense that his would go on my motor straight after mine went. Any help or suggestions is appreciated.

 

[rndn]

Re: Two spun props in two weeks why?

Are you positive the prop is spinning? Did you make a mark on the prop and hub and then notice the mark no longer lines up? You may have a gear issue.

 

[steelespike]

Re: Two spun props in two weeks why?

Did it thump like you hit something?Or just rev up?

 

[canemode]

Re: Two spun props in two weeks why?

The symptomwith the original prop was driving along asnormal, all fine and suddenly motor started screaming and lost forward thrust (like it had jumped out of gear), so tried again in forward a few times but same thing, I pulled up and tried in reverse, same thing happenned. So took it home, there is no back and forward movement in the shaft, a fraction of up and down movement (to small to measure but can feel it slightly. I put my neighbours prop on off same motor and tried it. It went fone for 20 minutes or so but then same thing happenned. It is a heavy open tinnie 4.92 metres that the 50 Johnson is pushing. It seems once the problem starts it gets worse and may as well pack up. Both times at idle or slightly higher it would hold but any real load and same problem.

I am pretty convinced the props have both spun, when you look at them it is very obvious.

My concern is that something else may be causing this and I could spend a fortune on props just to keep spinning them.

Has anyone ever heard of any other problem in the gearbox that could cause a prop to spin that I could check. Or do we think it is just that both props were old and the load of my boat just was enough to take them over the edge.

My neighbours boat is smaller and lighter than mine so it has not had as much load on it in the past.

Any comments, suggestions will help at this point.

 

[NelsonQ]

Re: Two spun props in two weeks why?

rndn is right. Mark the prop and verify that the prop is in fact spun before going any further.

 

[steelespike]

Re: Two spun props in two weeks why?

As suggested do the line test.I would suspect it is just a coinsedence and both are spun.My experience is it usually happens without warning though
I have had one that spun and then worked for a short time I think possibly that when it spun it setup as it stopped.Usually total failure is the first sign of trouble.