Broken Shaft

[aabbovet]

Hi All,

We were out this weekend in our 2011 Cutwater C-26, seas were 2 feet and we were cruising at 12-14 knots, not all that comfortable but doable, however, our shaft snapped at the level of the coupling, anyone else experience a shaft failure with their boat? other than a latent defect in the shaft, I can't come up with a good reason for this to happen, we are going to have the yard check the motor mounts to make sure they are secure as well as shaft alignment- the only other thing was that we were carrying a pudgy on our stern, could the extra weight, bouncing from the seas and engine load cause shaft failure in a young boat? Thanks so much for any thoughts/ advice
Andy

 

[knotflying]

Sounds very odd that a 1-1/4 shaft would snap. Usually the shaft fits into the flange and the flange is bolted onto the end of the shaft. Then there are two set screws that, when tightened, push against the sides of the bolt to prevent it from loosening. Additionally there is a key way. Is it possible that the key way sheared and it is the bolt that snapped and not the shaft? I could see a possibility of the stern being bounced out of the water and then a sudden submersion causing such a load over a period of time that a failure could possibly occur. Bad shaft alignment should have been detected much earlier with signs of vibration and an excessively worn cutless bearing.

Interesting to see what the mechanics find.

 

[rackline]

I have a friend who had a shaft break on a 3 year old Back Cove. No impact, wrap or other hardware issues. Manufacturer said it was faulty and replaced it.

 

[NorthernFocus]

The engine in your boat can't produce enough torque to wring the shaft. The mode of failure is almost surely fatigue that has been happening for some time. Likely a combination of an original defect in the shaft material and/or machining aggravated by misalignment.

That's a bad day on the water...

 

[aabbovet]

Thank you all, will post what I find out from the mechanics