Lost Prop on Passage

[Ddunmire]

Originally Posted by deblen

From the various part suppliers pics,It appears that some "long bolts" are hex head,in which case the tab lock washer would work (lock) fine.
But in other diagrams/pics,the "long bolt" appears to have a round "allan /socket" style head ,in which case,the tab lock washer would be useless against that round style head.

Cheers/Len

Makes sense

[SailingHarmonie]

Originally Posted by deblen

It appears some propellor cone kits contain the 23680979 tab lock washer & some don't.
With the tab lock washer properly installed,it appears nearly impossible for the long bolt to loosen.
Could the lack of tab lock washer contribute to frequent prop loss on these drives?
Cheers/Len


https://www.generalpropeller.com/sai...o-Penta-850396


https://fybmarine.shop/volvo-penta-f...umber-23680979


https://www.wholesalemarine.com/volv...79-lock-plate/

I agree, it “appears nearly impossible” yet I have had two boats with this system—installed correctly—that threw props. Never has this happened with any other prop securing method.

I don’t understand the failure mechanism because I have never caught one about to fail. It either looks perfect, or you’re left with an empty shaft and nothing to offer clue about what happened.

[fstbttms]

Originally Posted by SailingHarmonie

I agree, it “appears nearly impossible” yet I have had two boats with this system—installed correctly—that threw props. Never has this happened with any other prop securing method.

I don’t understand the failure mechanism because I have never caught one about to fail. It either looks perfect, or you’re left with an empty shaft and nothing to offer clue about what happened.

One of my clients is a sailing school with about 30 boats in its fleet, many of which have saildrives. Losing fixed-blade props off these saildrives is becoming something of a regular occurrence. At least 5 that I am aware of.

[Ddunmire]

Originally Posted by fstbttms

One of my clients is a sailing school with about 30 boats in its fleet, many of which have saildrives. Losing fixed-blade props off these saildrives is becoming something of a regular occurrence. At least 5 that I am aware of.

This seems like a very high failure rate for something that most boaters depend on for docking safely. I wonder if there’s a boater advocacy group that represents issues like this to OEM.

[skipperpete]

Yes, high failure rate of shafts and fairly regular loss of propellers but almost always due to less than ideal assembly procedures. There are a number of common fixes and Volvo have a splined lock washer that goes between the cone nut ( with flats) and the propeller. This big tab washer engages with the prop shaft spline and the tabs are bent to engage the cone nut flats. The long lock bolt can still be used as well for even more security.
Yanmar SD’s are notable for snapping off the propeller nut retaining thread and the fix for this is to bore out the end of the propshaft and thread it to accept a stud that has an identical thread to the cone nut with a threaded hole through its centre to accept the locking bolt. The large insert is loctited solidly in place and often the locking bolt is replaced by a long stud with locknuts or nylocs on the outer end and is similarly loctited solidly into the prop shaft. Folding propellers seem to be lost more often than fixed ones.

[SY Harmony]

Originally Posted by Ddunmire

Attachment 272744

That’s the fairing cone or a zinc depending. It’s not the prop nut.
The prop should be held on by a standard stainless hex nut with a locktab washer behind it. When properly installed it should not self loosen.

[SailingHarmonie]

Originally Posted by SY Harmony

That’s the fairing cone or a zinc depending. It’s not the prop nut.
The prop should be held on by a standard stainless hex nut with a locktab washer behind it. When properly installed it should not self loosen.

Should not, but it does. The world is not always as we think it should be.

[SY Harmony]

Originally Posted by SailingHarmonie

Should not, but it does. The world is not always as we think it should be.

Then it’s improperly installed.....
That type of fixation is used across thousands of applications in diverse stresses. It’s time tested and proven. But so is the lazyness of hired help......

[fstbttms]

Originally Posted by SY Harmony

That’s the fairing cone or a zinc depending. It’s not the prop nut.

Well, as a matter of fact it is the prop nut. The part is called the "propeller cone nut". Have a look:

[Jamme]

Originally Posted by fstbttms

Well, as a matter of fact it is the prop nut. The part is called the "propeller cone nut". Have a look:

Would you happen to also have a picture of the installation instructions that you could share with the readers?
Thanks and fair winds.

[fstbttms]

Originally Posted by Jamme

Would you happen to also have a picture of the installation instructions that you could share with the readers?
Thanks and fair winds.

Unfortunately, I do not.

[neilpride]

Dunno how many cones nuts are torqued properly and tightened with loctite.

[SY Harmony]

When properly installed the tab washer engages and locks the hex head bolt to the hex head of the cone nut. I stand by lazy installation.

[team karst]

My VP sail-drives have no lockwasher. It depends on the cone nut being torqued, and then the long bolt being torqued. There are thruholes in the sides of the cone to take a rod tool for torque.

[SY Harmony]

Originally Posted by team karst

My VP sail-drives have no lockwasher. It depends on the cone nut being torqued, and then the long bolt being torqued. There are thruholes in the sides of the cone to take a rod tool for torque.

Then drill the bolt head for seizing wire and call it locked