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18-12-2011, 02:39
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#1
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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CV Joint / Drive Shaft
Well, it is said that there are no stupid questions so here goes.
I have a Perkins 135HP pushing a 2.43:1 reduction gear to a 26" prop.
I would like thrust block and cv joint/flexible shaft connection. Looks like Python Drive, Aquadrive or Orion units. Which are fine but seems outrageously expensive for what is a very simple and old technology.
Is there any reason why I could not use a heavy duty auto CV joint/shaft which are sold for peanuts in comparison? I imagine there are autos which have torque and wear solutions far greater than needed for my little diesel.
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18-12-2011, 03:23
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#2
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Senior Cruiser
Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 10,594
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Re: CV Joint/Drive Shaft
no reason not to,but make sure you have a high quality thrust bearing on the prop coupling side.
we used a landrover fwd drive universal joint and a skf bearing mounted on a cross bearer glassed to the hull.
also make sure to leave plenty of room to repack the stuffing box.
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18-12-2011, 03:41
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#3
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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Quote:
Originally Posted by atoll
no reason not to,but make sure you have a high quality thrust bearing on the prop coupling side.
we used a landrover fwd drive universal joint and a skf bearing mounted on a cross bearer glassed to the hull.
also make sure to leave plenty of room to repack the stuffing box.
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This sounds practicable - easier for me to do in steel than glass I reckon. Thanks.
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18-12-2011, 04:04
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#4
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Senior Cruiser
Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 10,594
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Re: CV Joint/Drive Shaft
steel or glass depending on hull material.
just remember the bearing has to take all the thrust when in fwd and reverse so bearing and cross bearer must be robust as 135 hp engine creats a lot of force.
you might also think about incorporating a shaft generator into the design if the boat is a sailing vessel.
like this;
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18-12-2011, 04:21
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#5
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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Quote:
Originally Posted by atoll
steel or glass depending on hull material.
just remember the bearing has to take all the thrust when in fwd and reverse so bearing and cross bearer must be robust as 135 hp engine creats a lot of force.
you might also think about incorporating a shaft generator into the design if the boat is a sailing vessel.
like this;
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Hmmm, nice. Thnks
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18-12-2011, 05:26
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#6
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Registered User
Join Date: Sep 2009
Location: New Bern NC
Boat: Searunner 34 Trimaran
Posts: 1,660
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Re: CV Joint/Drive Shaft
Quote:
Originally Posted by stillbuilding
Well, it is said that there are no stupid questions so here goes.
I have a Perkins 135HP pushing a 2.43:1 reduction gear to a 26" prop.
I would like thrust block and cv joint/flexible shaft connection. Looks like Python Drive, Aquadrive or Orion units. Which are fine but seems outrageously expensive for what is a very simple and old technology.
Is there any reason why I could not use a heavy duty auto CV joint/shaft which are sold for peanuts in comparison? I imagine there are autos which have torque and wear solutions far greater than needed for my little diesel.
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I chose the Aqua Drive unit. It is more than a "U" joint. First off it has a thrust bearing that delivers the propulsion thrust, as well as the stresses from snagging a crab pot, to the engine bed, RATHER than the engine, it's rubber feet, or it's bearings.
Then it has TWO "U" joints, connected together by a short TELESCOPING shaft, all inside a rubber bellows. This allows the engine to be way out of alignment, and move all around, even for and aft shaking, without moving the prop shaft at all! The shaft just spins... This feature makes a dripless shaft seal, like my PSS, work infinitely better.
Together, these features make the engine's feet, bearings, and the shaft seal last much longer. It also makes it where engine to shaft alignment need not be constantly monitored or adjusted. Original alignment is much easier two.
We installed our engine within 5 degrees, 16 years and thousands of engine hours ago, and have never touched the alignment since. Although I may change the soft Yanmar rubber feet soon anyway, they have no sign of wear.
At the time, we paid $700 something for the small Aquadrive CV joint. While I could have cobbled together "something" cheaper, I could not even come close to creating something as utilitarian and long lived as this unit, for that price.
If you want one, buy it... IMO, it's a good deal!
M.
__________________
"Let us be kind to one another, for everyone you meet is fighting a hard battle".
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18-12-2011, 10:07
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#7
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Registered User
Join Date: May 2008
Location: Nova Scotia until Spring 2021
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,976
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Re: CV Joint/Drive Shaft
While I agree with the above and will be installing an Aquadrive unit shortly for precisely the same reasons (it's a steel boat and the reduction in vibration makes a HUGE difference), the OP can't use the "small" CV joint, because that's limited to 75 HP, if I recall. I have no idea what the "next one up" costs.
Nice installation, by the way.
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18-12-2011, 15:07
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#8
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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I do understand the benefits of the system. Just checking out options before committing to the substantial outlay.
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11-12-2012, 03:31
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#10
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Registered User
Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 1,020
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I am considering a change in transmissions with a resulting 7 degree misalignment. Anyone know if this is acceptable in real life situation?
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11-12-2012, 04:07
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#11
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Nearly an old salt
Join Date: Jun 2009
Location: Lefkas Marina ,Greece
Boat: Bavaria 36
Posts: 22,801
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Halyards Aquadrive will handle that
Dave
__________________
Interested in smart boat technology, networking and all things tech
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11-12-2012, 20:40
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#12
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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Re: CV Joint / Drive Shaft
Aqua Drive give a life expectation for the different units at 3 deg. misalignment. You would have to check with the company to see what 7 deg. would do.
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12-12-2012, 06:53
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#13
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Registered User
Join Date: May 2008
Location: Nova Scotia until Spring 2021
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,976
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Re: CV Joint / Drive Shaft
The point of an AquaDrive, to my understanding, is not to facilitate a permanent and intentional misalignment, but to allow transitory misalignments due to vibration-reducing "soft" motor mounts in a seaway.
A second feature is the isolation of the drive train from the prop shaft via the thrust bearing and the "cushioning" effect of the CV coupler.
Yeah, I have a steel boat. Seeing a soft mount/AquaDrive on a friend's boat and "not hearing it much", I was convinced. I'm doing the install over this winter.
I intend to labour a fair bit to get "zero degrees" dialled in. In other words, the engine at rest will be mated to the AquaDrive coupler as if it were a solid coupler. Then, when I get smacked by a wave while motoring off a lee shore and I'm heeled 30 degrees, I won't worry about alignment! That's how the CV joint should be, to my mind, employed.
Of course, I still have to watch my oil temperature running the engine at heel angles, but at least I won't bend the transmission linkages.
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07-01-2014, 19:51
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#14
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Registered User
Join Date: Jan 2014
Location: PA
Boat: 68 tartan 34c
Posts: 76
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Re: CV Joint / Drive Shaft
I am currently putting my own Aquadrive type system together. I have machined the thrust bearing housing and inserted opposing tapered roller bearings. My CV shaft is a new shaft for a 85 vw vanagon campervan. I cut the shaft in half, bored interference holes in a section of 1 and 1/4 shaft stock and pressed the vanagon shafts into the holes. I welded the ends and trued the shaft on the lathe. Being landlocked and working late in a machine shop to raise cash for the cruising kitting has to have some benefits. I will post some photos when I get it installed. The cv shaft is 43.5 inches long. We are moving the engine from the base of the companionway steps to just behind the mast. This is in a Tartan 34c. The engine is a 30 hp Yanmar. The thrust bearing will mount at the old atomic4 engine beds.
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08-01-2014, 11:37
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#15
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Registered User
Join Date: Jan 2014
Location: PA
Boat: 68 tartan 34c
Posts: 76
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Re: CV Joint / Drive Shaft
Here is a photo of my homemade shaft.
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