Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 27-04-2014, 11:46   #1
Registered User

Join Date: Apr 2014
Posts: 2
Yanmar SD20 prop shaft stub fracture

Doing some research on the internet it looks like the problem I have with my SD20 sail drive prop shaft is not unheard of! Putting the boat gently into reverse after a 4 hour motor (no wind) last week, the propeller came off and has gone forever!
As if this wasn't bad enough having hauled the boat onto a cradle it shows that about half of the externally and internally threaded stub has sheared off where a pre-drilled cross hole is. I understand Yanmar did away with the hole drilling on replacement shafts.
Has anyone succeeded in getting any compensation/ replacement from Yanmar as it seems to be a production failure as obviously weak and vulnerable to shearing.
May I ask one more thing? Has anyone repaired a shaft like this instead of replacing it? In the UK they cost well over $1000 and she`s an old boat but with a replacement Yanmar engine and sail drive 9 years ago , one that`s done very ]few hours since.
Thanks for your thoughts, Robin.
[ATTACH]80146[/ATTACH
Attached Thumbnails
Click image for larger version

Name:	IMG_0784.jpg
Views:	571
Size:	327.3 KB
ID:	80146  
__________________

__________________
Somadoc is offline   Reply With Quote
Old 28-04-2014, 12:00   #2
Registered User

Join Date: Apr 2014
Posts: 2
Re: Yanmar SD20 prop shaft stub fracture

Having thought about the risk associated with repair I have `bit the bullet` and bought a new prop shaft ..................

Do you think there`s the slimmest chance Yanmar might feel vaguely responsible?
__________________

__________________
Somadoc is offline   Reply With Quote
Old 28-04-2014, 14:14   #3
Marine Service Provider
 
fstbttms's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 3,592
Re: Yanmar SD20 prop shaft stub fracture

Replace a nine year old part for free? That doesn't seem likely or even reasonable to expect, frankly.
__________________
fstbttms is offline   Reply With Quote
Old 28-04-2014, 14:53   #4
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Yanmar SD20 prop shaft stub fracture

Quote:
Originally Posted by Somadoc View Post
Do you think there`s the slimmest chance Yanmar might feel vaguely responsible?
Look at your receipt again and think about that question

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 28-04-2014, 15:35   #5
Registered User

Join Date: Jun 2007
Location: SW Florida
Boat: FP Belize, 43' - Dot Dun
Posts: 3,423
Re: Yanmar SD20 prop shaft stub fracture

Quote:
Originally Posted by Somadoc View Post
Doing some research on the internet it looks like the problem I have with my SD20 sail drive prop shaft is not unheard of! Putting the boat gently into reverse after a 4 hour motor (no wind) last week, the propeller came off and has gone forever!
As if this wasn't bad enough having hauled the boat onto a cradle it shows that about half of the externally and internally threaded stub has sheared off where a pre-drilled cross hole is. I understand Yanmar did away with the hole drilling on replacement shafts.
Has anyone succeeded in getting any compensation/ replacement from Yanmar as it seems to be a production failure as obviously weak and vulnerable to shearing.
May I ask one more thing? Has anyone repaired a shaft like this instead of replacing it? In the UK they cost well over $1000 and she`s an old boat but with a replacement Yanmar engine and sail drive 9 years ago , one that`s done very ]few hours since.
Thanks for your thoughts, Robin.
[ATTACH]80146[/ATTACH
My sail drives are 11+ years old with no hole. I'm guessing that drive is at least 15 or more years old.

FWIW, the prop shaft in the US is ~$550.
__________________
DotDun is online now   Reply With Quote
Old 28-04-2014, 15:49   #6
Registered User
 
Cotemar's Avatar

Join Date: Dec 2007
Boat: FP, Helia 44 Evo
Posts: 5,717
Re: Yanmar SD20 prop shaft stub fracture

Quote:
Originally Posted by Somadoc View Post
Having thought about the risk associated with repair I have `bit the bullet` and bought a new prop shaft ..................

Do you think there`s the slimmest chance Yanmar might feel vaguely responsible?
Just be glad that you do not have the defective Yanmar SD40 and SD50 sail drives. Some cruisers are spending thousands per engine and still have a piece O sheet sail drive.
__________________
Cotemar is offline   Reply With Quote
Old 28-04-2014, 16:55   #7
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Yanmar SD20 prop shaft stub fracture

Our 1998 Volvo saildrive shafts have that hole also. I don't know about newer models. I have not heard of this problem on Volvos before (or Yanmar, for that matter - although you said it was an issue with them).

Make sure you buy the shim set because those shafts have to be shimmed exactly so that the helical gears mesh with the correct lash. There is a stamped number on the shaft and a calculation you do with it after taking a careful measurement. The answer tells you which shims you need to install.

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 29-04-2014, 00:54   #8
Registered User

Join Date: Nov 2010
Location: UK, Croatia
Boat: Fountaine Pajot Athena 11.6m Rapa Nui II
Posts: 378
Re: Yanmar SD20 prop shaft stub fracture

Its no help to you now, but it would seem to me that the cause of the failure was that the nut had been torqued up too high at some point in its history and that led to a fatigue failure. Its human nature to feel that torquing it up will make it more seure but the spline takes the prop torque and the nut only takes thrust in reverse. The split pin stops the nut coming off, not the nut torque. Saildrives are precision engineering and need a torque wrench otherwise you will get stripped threads etc
__________________

__________________
Rapanui is offline   Reply With Quote
Reply

Tags
yanmar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar SD20 Sail Drive Caution Strygaldwir Engines and Propulsion Systems 58 26-07-2017 13:21
SD20 prop Patcheloupe Engines and Propulsion Systems 6 26-12-2013 21:19
Rusted thru pipe stub in exhaust forsailbyowner Engines and Propulsion Systems 0 20-05-2012 06:07
Freak Wave - Compound Leg Fracture TaoJones Cruising News & Events 10 14-12-2009 14:33



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 04:37.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.