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22-01-2013, 10:03
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#31
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cat herder, extreme blacksheep
Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,967
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Re: Hard vs Soft Engine Mounts
hard mount prevents water ingress due to excessive vibration from the engine torquing on the soft mounts....
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22-01-2013, 11:33
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#32
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Registered User
Join Date: Jan 2011
Posts: 267
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Re: Hard vs Soft Engine Mounts
Sorry Zee but that is rather tenuous to say the least.
Correctly sized engine mounts and a flexible coupling are no more likely to cause leaks than rigid mounts. If your getting leaks (I assume from your referring to the stern gland) then check/ repack your stern gland more often.
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22-01-2013, 11:48
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#33
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cat herder, extreme blacksheep
Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,967
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by Artif
Sorry Zee but that is rather tenuous to say the least.
Correctly sized engine mounts and a flexible coupling are no more likely to cause leaks than rigid mounts. If your getting leaks (I assume from your referring to the stern gland) then check/ repack your stern gland more often.
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rodlmao.
no leaks--merely COMPLETE destruction of drive line, as it were. packing gland destroyed, etc DUE TO soft mounts mis-aligning engine. fact.
not leaks..
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22-01-2013, 11:59
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#34
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Registered User
Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch (and +3 smaller)
Posts: 2,738
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Re: Hard vs Soft Engine Mounts
Don't remember presicely but reckon soft mounts became merely available about thirtyfive yrs ago? Thou before that some builded their drive train with car front wheel shafts (CV joints) coupled with pressure bearings and mounted the engine on non-marine soft mounts..
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22-01-2013, 12:08
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#35
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Moderator
Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,156
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by ccgarnaal
My engine is hard mounted (1962) I loosened the shaft coupling and check the alignment when I bought the boat it was correct to 0.001mm after 50 years.
I still haven't seen any soft mounts lasting 50 years.
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I am curious how you measured your alignment to that degree of accuracy... .001 mm is one micron, and that is a pretty thin feeler gage!
Cheers,
Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
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22-01-2013, 14:16
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#36
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Registered User
Join Date: Jan 2011
Posts: 267
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by zeehag
rodlmao.
no leaks--merely COMPLETE destruction of drive line, as it were. packing gland destroyed, etc DUE TO soft mounts mis-aligning engine. fact.
not leaks..
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And that was due to soft engine mounts
More likely failed engine mounts, poor alignment, or incorrect mounts for the engine, they are weight and power dependent.
Even with flexi mounts, alignment is absolutely critical.
I currently play around with 15,000 hp electric motors which are semi rigidly mounted, but the motor to gearbox and gearbox to final drive are all connected with flexible couplings to ensure the drive train doesn't strain the bearings. The couplings are 4ft in diameter and aligned to 0.004" at worst, we usually hit 0.002".
P.s. the above system was designed in the 50's and been in commission since the late 60's without failure.
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22-01-2013, 16:11
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#37
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Registered User
Join Date: Mar 2003
Location: Philippines in the winters
Boat: It’s in French Polynesia now
Posts: 11,368
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by Jim Cate
I am curious how you measured your alignment to that degree of accuracy... .001 mm is one micron, and that is a pretty thin feeler gage!
Cheers,
Jim
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Hell, the couplings aren't even that accurate.
Not unless they were machined on their prop and tranny shafts. But unless it's a hi-speed system (Hydroplanes) it's a waste of funds.
Every prop shaft I've measured wasn't even round within .001"
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
The measure of a man is how he navigates to a proper shore in the midst of a storm!
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22-01-2013, 16:17
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#38
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Registered User
Join Date: Mar 2009
Location: Australia, Hervey Bay QLD
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 909
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Re: Hard vs Soft Engine Mounts
He probably would have done it because it is cheaper, simpler to align and bulletproof.
If ever you re do with soft mounts, consider using a Aquadrive or similar CV joint kit.
Regards,
Richard.
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22-01-2013, 16:32
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#39
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Registered User
Join Date: Mar 2003
Location: Philippines in the winters
Boat: It’s in French Polynesia now
Posts: 11,368
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by boden36
If ever you re do with soft mounts, consider using a Aquadrive or similar CV joint kit.
Regards,
Richard.
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+1 on that! Especially the smaller Yanmars. I had to mount and then remount mine, the second time using a Pythondrive, to get the prop shaft from vibrating. Yanmar's really soft mounts don't like pushing the boat.
.
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
The measure of a man is how he navigates to a proper shore in the midst of a storm!
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23-01-2013, 11:21
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#40
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cat herder, extreme blacksheep
Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,967
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by Artif
And that was due to soft engine mounts
More likely failed engine mounts, poor alignment, or incorrect mounts for the engine, they are weight and power dependent.
Even with flexi mounts, alignment is absolutely critical.
I currently play around with 15,000 hp electric motors which are semi rigidly mounted, but the motor to gearbox and gearbox to final drive are all connected with flexible couplings to ensure the drive train doesn't strain the bearings. The couplings are 4ft in diameter and aligned to 0.004" at worst, we usually hit 0.002".
P.s. the above system was designed in the 50's and been in commission since the late 60's without failure.
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do not try to advise me as to the exact progression of these symptoms--i KNOW what is the problem and i KNOW exactly when these symptoms began and , yes, i DO have a GOOD, if not EXCELLENT mechanic.....as i stated the problem is exactly how it is in reality. . rodlmao. i loove how folks HAVE to attempt to interpret the actualities to the onliest versions that are acceptable to within their specific rigidities....as you are not here in my boat learning the exact why-fors and where-bys, perhaps you should refer only to that which you KNOW..this is not that. thankyou for your interesting commentry.(as opposed to commentary. yes i know my languages.)
alignment doesnt just fall out..lol...is caused to mis-align. think beyond the alignment to the cause there of.....this is a measurable fact.
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23-01-2013, 11:32
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#41
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cruiser
Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
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Re: Hard vs Soft Engine Mounts
If it's not broke, don't fix it.
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23-01-2013, 11:53
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#42
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cat herder, extreme blacksheep
Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,967
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Re: Hard vs Soft Engine Mounts
truth, tc!!!!
the difference between mechanic and boatwright is the mechanic only sees the machine. the boatwright sees the entire picture, and is able to repair the entire problem......
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23-01-2013, 14:20
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#43
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Registered User
Join Date: Jan 2011
Posts: 267
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Re: Hard vs Soft Engine Mounts
Quote:
Originally Posted by zeehag
truth, tc!!!!
the difference between mechanic and boatwright is the mechanic only sees the machine. the boatwright sees the entire picture, and is able to repair the entire problem......
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2 years studying boatbuilding = certified shipwright, wood and composites
2 years building boats commercial and racing cats
4 years marine engineering apprenticeship
Certified welding inspector
etc
etc
20 years working in engineering from ships to Fusion reactors
Rebuild wooden boats for a hobby
Paid for work on boats in my spare time
but what the hell do I know
best of luck to you
adios
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23-01-2013, 21:06
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#44
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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This discussion has me thinking I will revert to hard mounting my Perkins and avoid the costs of soft mounting and flexible drive train. Steel boat but I think 6 cylinders may not be too bad.
Anyone with hard mounts care to comment on 6 cyl or Perkins specifically.
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23-01-2013, 21:41
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#45
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Registered User
Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
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Re: Hard vs Soft Engine Mounts
Page 25 of the DIECON catalogue has their mounts which are remarkably like polylex at less expense.
Diecon Catalog
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