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Spun prop Volvo saildrive
When doing the final job to launch the boat, servicing the 2 blade folding prop on my saildrive, I found that the prop was partially spun. The situation appears to be that the internal spline insert in the prop hub rotated slightly within the hub itself. I was told by a tech at the yard that it is a designed failure point to protect the drive in the event of a grounding or extreme fouling, the prop assembly gives before it can transfer damage to the drive components. There was never any event on the boat last season, there was less than 30 hours total run time so I would have noticed something like that. It appears as if the internal spline assembly started to give and the stainless spacer that seperates it from the hub itself deformed and caught on the shoulder of the prop nut, building a small ridge which than jammed in the gap between the 2 parts. When I removed the prop nut it was extrmely difficult and appears to have sheared the shoulder off the bronze nut as it passed over the ridge in the stainless.
The prop itself never actually failed, and there is no visiable damage to it, it was never fouled, so there is no way to know when or how this happened. Obviously, the force was not sufficient to cause the designed protection failure to occur. My speculation revolves around the force when the boat was shifted from forward or reverse into the opposite gear and the engine was throttled up hard, like when trying to substantially reduce speed.
Has anyone heard of or experienced a similar failure of a Volvo prop. I was advised by one person at the yard to just punch the ridge on the spacer down flat and make a thin stainless washer to go over the said spacer and put it back together. Another, the parts person, told me that, that probably wasn't a good idea as I would discover it didn't work after the boat was launched I put the prop under load and it failed and would than need to immediately have the boat hauled for repair. The yard checked and Volvo doesn't provide any warranty on props and a new hub is $500.00
Would appreciate any feedback on this.