Prop strike on a log

So here in Pittsburgh the season is just starting and the river has been full of debris. Yesterday we smacked log moving pretty good and afterwards the boat/engine had a substantial vibration at idle. We putzed back to shore without throttling up because the vibration would just increase.

So the obvious things to check are the prop, shaft, and strut. Out of the water they all really appear to be in good shape. I know with the shaft a minor bend could be thought to see so I'll probably take it out and see how it rolls and maybe take to shop to get looked at.

The strange thing is that when going to put the boat in reverse the engine shuts off and when the boat is in neutral it seems it is a bit throttled up. Any ideas on what would have cause this issue after a big prop strike?

Boat is an 85 Sunsport do these have a kill switch or something that may be getting hit could this be transmission related? Or maybe something in the throttle mechanism?

So we took the prop off and inspected it and it appears to be fine so we reinstalled that and it runs smooth again. I think the hit knocked it out of alignment on the shaft...won't know for sure until on the water.

We tried adding some additive to the transmission case to potentially free or assist any stuck plates but that did not to help.

The boat still dies in reverse but if you eliminate the linkage at the transmission the boat can throttle into reverse just fine. So the issue is isolated to the transmission it seems? Why would it die in reverse...would that be just because the plates are seased up? Is there a kill switch that kills the engine if the tranny is locked up?

Do these issues sound like the tranny is shot from an aggressive prop strike while throttled?

Is there anything else that can be looked at to hopefully not having to rebuild the clutch?

Quote:

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Originally Posted by Nickgb55

So we took the prop off and inspected it and it appears to be fine so we reinstalled that and it runs smooth again. I think the hit knocked it out of alignment on the shaft...won't know for sure until on the water.

We tried adding some additive to the transmission case to potentially free or assist any stuck plates but that did not to help.

The boat still dies in reverse but if you eliminate the linkage at the transmission the boat can throttle into reverse just fine. So the issue is isolated to the transmission it seems? Why would it die in reverse...would that be just because the plates are seased up? Is there a kill switch that kills the engine if the tranny is locked up?

Do these issues sound like the tranny is shot from an aggressive prop strike while throttled?

Is there anything else that can be looked at to hopefully not having to rebuild the clutch?

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I'm not an expert by any means, just my $ 0.02 - I'm thinking the vibration damper is damaged. One thing is for certain, you'll do more damage running it trying to diagnose the issue. Even if it means having a shop look at it, it'll likely save you $$$ in the long run.

Brian

btw, if you'd like to have a spare prop around in case running amidst logs is a regular thing for you (as it is for me early in the season), I have an OJ 13x15.5 428 prop that needs a new home after I sold my Supra. LMK.

Quote:

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Originally Posted by Nickgb55

So we took the prop off and inspected it and it appears to be fine so we reinstalled that and it runs smooth again. I think the hit knocked it out of alignment on the shaft...won't know for sure until on the water.

We tried adding some additive to the transmission case to potentially free or assist any stuck plates but that did not to help.

The boat still dies in reverse but if you eliminate the linkage at the transmission the boat can throttle into reverse just fine. So the issue is isolated to the transmission it seems? Why would it die in reverse...would that be just because the plates are seased up? Is there a kill switch that kills the engine if the tranny is locked up?

Do these issues sound like the tranny is shot from an aggressive prop strike while throttled?

Is there anything else that can be looked at to hopefully not having to rebuild the clutch?

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Sounds like internal damage to the transmission. Time to pull it out.

Quote:

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Originally Posted by scottschmitt

btw, if you'd like to have a spare prop around in case running amidst logs is a regular thing for you (as it is for me early in the season), I have an OJ 13x15.5 428 prop that needs a new home after I sold my Supra. LMK.

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I will send you a PM

I have it in with a local guy now. He does not seem worried about the transmission and seems to think the prop shaft is somehow bound up in the prop strut. You can not spin the prop freely on the trailer it is pinchrd tight somewhere. But more to come on that as he gets into it. Fortunately looks like insurance will take the claim on it.

Even if it is the tranny I'll just have him do what he needs to get it going again. He is not with a marina or boat garage so he should not beat me up to bad on price.

Quote:

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Originally Posted by Nickgb55

I have it in with a local guy now. He does not seem worried about the transmission and seems to think the prop shaft is somehow bound up in the prop strut. You can not spin the prop freely on the trailer it is pinchrd tight somewhere. But more to come on that as he gets into it. Fortunately looks like insurance will take the claim on it.

Even if it is the tranny I'll just have him do what he needs to get it going again. He is not with a marina or boat garage so he should not beat me up to bad on price.

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Make sure when you pull the driveshaft that you check the strut for alignment. I bought mine 2004 used, and found out the hard way last summer that the previous owner had hit something and bent the strut. The shaft nut came loose on the river and the driveshaft slid back until the rudder stopped it. Had to get towed back to port. After I crawled under the boat for a further inspection, I could see where he had pounded on it with a hammer trying to straighten it. When I slid the driveshaft back through the strut towards the stuffing box in the boat, the strut had been bent an 1-1/2" off center. Fortunately I work in shop where I could straighten the strut. I also bought a new driveshaft assembly.