Topics

SM Prop Shaft Seal direction and Bushing

Craig Briggs SN 68 Sangaris
 

OK, Jose, we've got a date for two years from now (or 400 hours, or milky oil; whichever comes first!).

My reading of the SKF engineer's recommendation was that the inner seal would face the oil and the outer two would face the water, but on re-reading it he really wasn't explicit on that, possibly assuming a conventional oil-facing orientation.

Not that I'm "buying it" yet, but I do follow your logic of putting the inner seal in "backwards", ie. facing out to allow oil to seep out and lubricate the other seals (and water to seep in through the outer seal and also provide lubrication). I say "backwards" as compared with a conventional lip seal application, say your engine's main crank shaft where the seals face the oil and get no lubrication (other than microscopic oil seepage, perhaps, or, of course, if it's the rear seal of a Perkins 4-108 that always leaks profusely!). 

Moreover, in "normal" applications the lips are rubbing against a very hard shaft, which I really think is the crux of the problem, ie., our bearing is too soft, rather than the orientation of the seals. 

To be continued...
Cheers, Craig SN68 Sangaris




---In amelyachtowners@..., <jvenegas@...> wrote :

Thank you Craig, A truly interesting post.

I was interested to see that in your post about the SKF expert he/she states 
 "Finally, I would arrange the seals with 2 facing the water and one facing the oil as long as there is no pressure difference."
 
THIS IS EXACTLY WHAT I DID IN MY EXPERIMENT! Plus I would add that the 2 seals facing the water should be the central and inner seals to make sure they get lubricated when the grease wears out AND THE OUTER SEAL deteriorates.

PS;  Since you used the AMEL seal configuration and the standard bronze bushing, and I did it at the same time but with the two seals facing the water, in two years we should compare results.

Fair winds

Jose
 

Mike Longcor (SV Trilogy)
 

Hi Everyone, Craig and Jose especially,

I'm preparing to service the prop shaft wear bushing and seals. Curious how your seal orientations have worked out. Is the oil in the reservoir staying clean and constant level?

Any chance there is now consensus among the community or from Amel on this? I'm planning to follow the "Shaft Bushing and Seals Replacement" procedure posted by Eric and Gary.

Haven't had any problems with my C-Drive or the oil. I don't know when it was last serviced but at least 2.5 years, probably more(!). I'm curious to see how they are oriented when I take them out. I'm inclined to reinstall them the same way given the good performance.

Does anyone have any new data or current recommendations regarding these three seals?

Thanks,
Mike Longcor
SV Trilogy - SM23
Opua, NZ

Craig Briggs SN 68 Sangaris
 

Hi Mike,
I suspect there is nothing new on this nor any particular consensus - it may well have migrated from engineering to philosophy ;-)
If yours is fine you may want to follow the adage of, "If it ain't broke, don't fix it".  Or change it and in a couple of years add to the anecdotal evidence being accumulated.
Cheers, Craig

Scott SV Tengah
 

Mike,

I have two aft seals facing out and fore seal facing in. "facing" to me indicates which way the spring is.

I am about 650 hours on these seals and zero water ingress and zero drop in oil level. It was probably a bad installation but previously I did it "the Amel way" and had to haul out again at around 300 hours due to milky c drive oil.

PS - where are you getting the work done in NZ? We will be there in November and will be due for a haul out then.
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

Jean-Pierre Massicotte
 

Hello Mike, Amel recommandations is to change the seals and bushing every 700 h of use. Also recommend 2 seals protecting the oil side and one on the water side.

We before crossing the Pacific we reverse this logic since haul up facility are fare apart and if water get in here it could make a big mess in the engine room by over flowing.
(We use the shaft alternator during all crossing)
It's very important to clean well the seal seating on the water side and make sure no residue remain.

Regards

Jean Pierre Massicotte
SN 51

On Sun., Feb. 9, 2020, 09:51 Craig Briggs SN 68 Sangaris via Groups.Io, <sangaris=aol.com@groups.io> wrote:
Hi Mike,
I suspect there is nothing new on this nor any particular consensus - it may well have migrated from engineering to philosophy ;-)
If yours is fine you may want to follow the adage of, "If it ain't broke, don't fix it".  Or change it and in a couple of years add to the anecdotal evidence being accumulated.
Cheers, Craig

 

If you had a choice of:
Choice A protecting the loss of oil and destruction of the C-Drive
Choice B protecting from some seawater intrusion causing a haulout
Which would you choose?
image.png


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
   
View My Training Calendar
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On Sun, Feb 9, 2020 at 11:15 AM Jean-Pierre Massicotte <Massicotte.j.p@...> wrote:
Hello Mike, Amel recommandations is to change the seals and bushing every 700 h of use. Also recommend 2 seals protecting the oil side and one on the water side.

We before crossing the Pacific we reverse this logic since haul up facility are fare apart and if water get in here it could make a big mess in the engine room by over flowing.
(We use the shaft alternator during all crossing)
It's very important to clean well the seal seating on the water side and make sure no residue remain.

Regards

Jean Pierre Massicotte
SN 51

On Sun., Feb. 9, 2020, 09:51 Craig Briggs SN 68 Sangaris via Groups.Io, <sangaris=aol.com@groups.io> wrote:
Hi Mike,
I suspect there is nothing new on this nor any particular consensus - it may well have migrated from engineering to philosophy ;-)
If yours is fine you may want to follow the adage of, "If it ain't broke, don't fix it".  Or change it and in a couple of years add to the anecdotal evidence being accumulated.
Cheers, Craig

Mike Longcor (SV Trilogy)
 

Thanks everyone for your thoughts on this. I appreciate both schools of thought here. Great diagram Bill, I'm hoping to find my current seals in this orientation. I'll report back any worthwhile findings when I do this job in April. I'm sure thorough prep and careful installation are crucial.

Mike Longcor
SV Trilogy - SM23
Opua, NZ


On Tue, Feb 11, 2020, 5:46 AM CW Bill Rouse <brouse@...> wrote:
If you had a choice of:
Choice A protecting the loss of oil and destruction of the C-Drive
Choice B protecting from some seawater intrusion causing a haulout
Which would you choose?
image.png


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
   
View My Training Calendar
cloudHQPowered by
cloudHQ


On Sun, Feb 9, 2020 at 11:15 AM Jean-Pierre Massicotte <Massicotte.j.p@...> wrote:
Hello Mike, Amel recommandations is to change the seals and bushing every 700 h of use. Also recommend 2 seals protecting the oil side and one on the water side.

We before crossing the Pacific we reverse this logic since haul up facility are fare apart and if water get in here it could make a big mess in the engine room by over flowing.
(We use the shaft alternator during all crossing)
It's very important to clean well the seal seating on the water side and make sure no residue remain.

Regards

Jean Pierre Massicotte
SN 51

On Sun., Feb. 9, 2020, 09:51 Craig Briggs SN 68 Sangaris via Groups.Io, <sangaris=aol.com@groups.io> wrote:
Hi Mike,
I suspect there is nothing new on this nor any particular consensus - it may well have migrated from engineering to philosophy ;-)
If yours is fine you may want to follow the adage of, "If it ain't broke, don't fix it".  Or change it and in a couple of years add to the anecdotal evidence being accumulated.
Cheers, Craig

 

Mike, 

My guess is that 99% of water egress is caused by one or more of these mistakes/omissions:
1.) Seals and/or wear bushings NOT purchased from Amel.
2.) The wall of the seal cavity NOT completely cleaned with emery cloth (see below).
3.) The seals NOT oriented according to Amel specs.
4.) The seals NOT inserted the correct depth.
5.) The seals NOT completely greased with waterproof grease
6.) The wear bushing O ring NOT greased and/or not the correct size
7.) The propeller shaft NOT completely cleaned where the wear bushing O ring meets the shaft.
8.) Did not follow the instructions
9.) Trusted a mechanic who said he could do the job

Here is a really good tip for you:
To clean the inside wall of the seal cavity, use a curved file with 400 grit 
wet/dry sandpaper wrapped around the end. This must be clean and smooth. 
Ensure this is done correctly.
image.png


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
   
View My Training Calendar
cloudHQPowered by
cloudHQ


On Mon, Feb 10, 2020 at 4:01 PM Mike Longcor (SV Trilogy) <svtrilogy53@...> wrote:
Thanks everyone for your thoughts on this. I appreciate both schools of thought here. Great diagram Bill, I'm hoping to find my current seals in this orientation. I'll report back any worthwhile findings when I do this job in April. I'm sure thorough prep and careful installation are crucial.

Mike Longcor
SV Trilogy - SM23
Opua, NZ

On Tue, Feb 11, 2020, 5:46 AM CW Bill Rouse <brouse@...> wrote:
If you had a choice of:
Choice A protecting the loss of oil and destruction of the C-Drive
Choice B protecting from some seawater intrusion causing a haulout
Which would you choose?
image.png


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
   
View My Training Calendar
cloudHQPowered by
cloudHQ


On Sun, Feb 9, 2020 at 11:15 AM Jean-Pierre Massicotte <Massicotte.j.p@...> wrote:
Hello Mike, Amel recommandations is to change the seals and bushing every 700 h of use. Also recommend 2 seals protecting the oil side and one on the water side.

We before crossing the Pacific we reverse this logic since haul up facility are fare apart and if water get in here it could make a big mess in the engine room by over flowing.
(We use the shaft alternator during all crossing)
It's very important to clean well the seal seating on the water side and make sure no residue remain.

Regards

Jean Pierre Massicotte
SN 51

On Sun., Feb. 9, 2020, 09:51 Craig Briggs SN 68 Sangaris via Groups.Io, <sangaris=aol.com@groups.io> wrote:
Hi Mike,
I suspect there is nothing new on this nor any particular consensus - it may well have migrated from engineering to philosophy ;-)
If yours is fine you may want to follow the adage of, "If it ain't broke, don't fix it".  Or change it and in a couple of years add to the anecdotal evidence being accumulated.
Cheers, Craig

Mike Longcor (SV Trilogy)
 

Thank you Bill. Those are great tips. Do you have a favorite grease for this job? Is Molykote a good choice?

Mike Longcor
SV Trilogy SM23
Opua, NZ

 

You're welcome  I always used normal waterproof wheel/axel grease. 

Best,

CW Bill Rouse
Amel Owners Yacht School - www.AmelOwnersYachtSchool.com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970

On Mon, Feb 10, 2020, 5:48 PM Mike Longcor (SV Trilogy) <svtrilogy53@...> wrote:
Thank you Bill. Those are great tips. Do you have a favorite grease for this job? Is Molykote a good choice?

Mike Longcor
SV Trilogy SM23
Opua, NZ

Alan Leslie
 

Mike,

I'll be on Elyse in Opua in April preparing for the trip to Fiji, if you would like any assistance or advice.
I've done the C-drive seal replacement job quite a few times now without issues.

Cheers
Alan
Elyse SM437
G21 Opua

Mike Longcor (SV Trilogy)
 

Alan that sounds great. We might haul out in one of the yards in Whangarei, but I'd definitely appreciate chatting with you on this and other topics.

Cheers,
Mike Longcor
SV Trilogy SM23
Opua, NZ