Shaft disconnected from transmission

[chesapeake8]

After a several hour sail on our Oceanis 321 this afternoon , upon entering our creek and firing up our engine, we found ourselves with no forward or reverse movement. Inspection revealed shaft separated at transmission.  Coupling likely prevented shaft from completely exiting boat.  Wondering if anyone has seen or experienced,  knows what part may have failed, and what's likely going to be necessary to repair?

Pictures attached.

Thanks,

Christopher

[Captain Guy]

Been there done that...

 

where is the nut and key, tho it looks like splines in the coupler????

 

If it just came loose and separated, then re-assembly is a piece of cake.  If the taper on the shaft is trashed, then a new shaft is necessary.  I change to a different type of coupler with a compression clamp rather than key and nit.  It ws cheaper and did not require machining the engine end of the shaft and provided some adjustments.

 

New “B” shafts come with prop end machined, then you cut an machine the taper and key and thread on coupler end.  My new coupler just clamps toa plain shaft end (no machining).

 

If you wan tot use new shaft with old style coupler, “B” has engineering drawings (I have them if needed)

 

Guy

 

0352 #277

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[David Fletcher]

Take a look in bottom of the hull area. Most likely you will find the old bolts which have come loose and  dropped out.

Slip the shaft back together and rebolt it with nylock nuts and check the torque after 5 or 10 hours.

Did somebody have it apart recently.

David Fletcher

136 Augusta

Blue Mountain

[chesapeake8]

Nut that was supposed to hold flange on transmission side was found inside coupler. No obvious mechanism (key) seen to ensure this nut stays connected to transmission drive end. Mechanic said he's never seen one like this.

Hasn't been apart in the four years we have had the boat.

[Captain Guy]

Standard way is:

 

Shaft out of tranny is tapered, has a keyway, threaded on end (see your picture).

There is a key

Coupler flange tapped on to taper

Nut tightened to end of shaft

 

re-attach prop shaft with 4 bolts.

 

BTW, the prop shaft is also tapered, has key and nut on end.

 

Guy

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[Bill Jarvis]

Guy,

 

While that is pretty much standard the photo of this one shows an internal spline in the coupling and a splined shaft.

 

In my opinion that is fine so long as the nut is locked so that it cannot come undone as this one did.

 

Bill

[chesapeake8]

Bill, any suggestions on how I can keep the nut locked?

I'm also wondering why this happened now. So, let me add two other bits of information. Four weeks ago, I replaced the original, 3-blade fixed prop with another 3 blade fixed. I also started putting the transmission in reverse when under sail.

Christopher

[Bill Jarvis]

Christopher,

 

Putting the prop in reverse when sailing would cause a torque that would tend to unscrew the nut off the end of the tranny shaft.

 

My suggestion would be to reinstall the flange to the transmission, tighten the nut and then drill a hole for a cotter pin to stop it from unscrewing. Failing that sue two thin nuts and Locktight, red.

 

Bill

[Jeffrey Schwartz]

Use the correct bolt and nut...not hardware store SS... these are hardened special bolts/nuts. Also use lock washer and lock tight.

 

 

Jeffrey Schwartz

 

From: benetea...@googlegroups.com [mailto:benetea...@googlegroups.com] On Behalf Of chesapeake8

Sent: Monday, August 25, 2014 10:41 AM
To: benetea...@googlegroups.com

[Captain Guy]

jeff, flange did not separate, only the nut holding flange to output shaft...

 

BTW torque in R would not loosen the big nut

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[Captain Guy]

I’m sure you’re in good hands... however, wish your photos were sharper... whilehte coupler appears to have splines, the outout shaft looks normal tapered?

 

Very puzzling.

 

Guy

 

From: chesapeake8

Sent: Saturday, August 23, 2014 9:21 PM

To: Benetea...@googlegroups.com

Subject: {Beneteau Owners} Shaft disconnected from transmission

 

After a several hour sail on our Oceanis 321 this afternoon , upon entering our creek and firing up our engine, we found ourselves with no forward or reverse movement. Inspection revealed shaft separated at transmission.  Coupling likely prevented shaft from completely exiting boat.  Wondering if anyone has seen or experienced,  knows what part may have failed, and what's likely going to be necessary to repair?

Pictures attached.

Thanks,

Christopher

[B F-405]

I had a similar problem on my previous C&C 41 with a Yanmar 4GM engine.  It started making a thump when shifting from forward to reverse and back.  Upon inspection the transmission flange coupling was loose on the tranny side as the nut had backed off.  I cleaned it all up/degreased the threaded area, coated it with loc-tite and re-torqued the nut - which as I recall was something like 100 ft lbs - the spec is in the manual.  That was the hardest part - it took a large pipe wrench to hold the coupling from rotating while getting the torque.