Hit a stump - driveshaft snapped

[trendsetter240]

Heading back up the river at dusk after an evening of fishing I hit a stump that was about a foot beneath the surface of the water.

The impact made the outboard kick up right out of the water, cowling flew off, fuel line came off and the engine revved way up to 6700RPM.

I stopped the motor immediately and fired up my kicker motor. I trimmed up the main motor and could see that there was wood sticking out from the prop area and that the gearcase had seperated about an inch from the mid section. I used the kicker to retrieve the cowling out of the water and headed in.

After a two hour ride in at 3.3mph I got back to the dock and had a closer look at the damage. Found this.

 

[trendsetter240]

Re: Hit a stump - driveshaft snapped

The next day (yesterday) I removed the lower unit to find that 4 of the bolts holding the leg on had been sheared off and the drive shaft was snapped in two. The LU was being held on by one bolt and the shift rod.


Here you can see the drive shaft sheared off in the impeller housing.

Broken driveshaft.

Engine midsection.

 

[HighTrim]

Re: Hit a stump - driveshaft snapped

Sorry to hear that.

I did the same thing on Sturgeon Lake in the Kawarthas on the Trent Severn.

you must have been really motoring!

 

[trendsetter240]

Re: Hit a stump - driveshaft snapped

Now luckily I do have 2 spare lower units for this motor. However, I will need to drill and retap the bolt holes after I remove the broken pieces.

In the meantime, I have a spare complete 93 Evinrude 70hp that I will use till the end of the season.

 

[trendsetter240]

Re: Hit a stump - driveshaft snapped

Sorry to hear that.

I did the same thing on Sturgeon Lake in the Kawarthas on the Trent Severn.

you must have been really motoring!

Yeah it sucks..I won't be able to fish for at least 3 days now!

I was going full throttle, which on this boat heading up river is about 33-35 MPH. Must have hit it at just the right angle.

 

[F_R]

Re: Hit a stump - driveshaft snapped

I just have to wonder how that last bolt got unscrewed that quickly. The one that saved the gearcase from falling off. Seems odd..??????

 

[trendsetter240]

Re: Hit a stump - driveshaft snapped

I just have to wonder how that last bolt got unscrewed that quickly. The one that saved the gearcase from falling off. Seems odd..??????

The one remaining bolt was still tight. There was no gap at the front of the gearcase where that bolt was. It was the other 4 that were sheared off.

My thoughts are that after the impact the rear of the gear case dropped an inch and put pressure on the drive shaft. Then as the piece of wood seen in the first pic jammed in between the prop and case at 6700 RPM the drive shaft snapped off.

Sound logical? Any other ideas?

 

[HighTrim]

Re: Hit a stump - driveshaft snapped

I guess there was no marker for this shallow an area eh? What lake were you on?

 

[F_R]

Re: Hit a stump - driveshaft snapped

The one remaining bolt was still tight. There was no gap at the front of the gearcase where that bolt was. It was the other 4 that were sheared off.

My thoughts are that after the impact the rear of the gear case dropped an inch and put pressure on the drive shaft. Then as the piece of wood seen in the first pic jammed in between the prop and case at 6700 RPM the drive shaft snapped off.

Sound logical? Any other ideas?

Sure it's logical. If the gearcase dropped on one end, the shaft was running outof alignment, bending as it did. Dosen't take much bending back and forth to break it.

 

[tx1961whaler]

Re: Hit a stump - driveshaft snapped

You'll be fortunate if the midsection is not bent also. If your driveshaft breaks again you'll know it is.

 

[trendsetter240]

Re: Hit a stump - driveshaft snapped

I guess there was no marker for this shallow an area eh? What lake were you on?

Nope, no marker. This was in the Fraser river and I was in the channel about 15 feet deep.

There are a lot of loose logs that are left by the tug boats. Most of them float and are easy to spot but is the odd one that gets lodged into the bottom and one end sits just below the surface.