CV Driveshaft Experience

[stillbuilding]

I have a steel yacht, 135HP Perkins 2.43 2 1/4 shaft, fixed 25" 3 blade prop with a Pegasus shaft seal and two cutlass bearings.
Engine space is close to stateroom so want it as quiet as possible.
My thought is flexible mountings and a CV drive shaft - Python drive or Aquadrive. I do understand that a few degrees of "misallignment" is required for these CV joints. Does anyone have any experience of these drives? Recommendations? Flexible mounts the best way - stiffer or more flexible?
Am I introducing any problems?
Thanks.
Richard

[James S]

I've not used CVs Richard...and not sure how big/heavy an engine you can go with flex mounts.
I can tell you that you can get a lot of noise through your exhaust system.
I isolated pretty much all I could with rubber mounts...it brought the "rumble" sound down quite a bit.

[James S]

I don't recall the brand, but when I looked at CVs it seemed like they were quite long...the one I was interested in also managed thrust...the assembly was fixed hard to a small bulkhead of sorts...seems like the whole thing was around 17inches long, of something crazy like that..

[S/V Alchemy]

Originally Posted by stillbuilding

I have a steel yacht, 135HP Perkins 2.43 2 1/4 shaft, fixed 25" 3 blade prop with a Pegasus shaft seal and two cutlass bearings.
Engine space is close to stateroom so want it as quiet as possible.
My thought is flexible mountings and a CV drive shaft - Python drive or Aquadrive. I do understand that a few degrees of "misallignment" is required for these CV joints. Does anyone have any experience of these drives? Recommendations? Flexible mounts the best way - stiffer or more flexible?
Am I introducing any problems?
Thanks.
Richard

I am shortly installing an Aquadrive on a steel motorsailer. My understanding is that a "few degrees of misalignment" is to be avoided: You install the engine on soft mounts and get the thrust bearing perfectly lined up along with the shaft coupler, Aquadrive and engine side, and then you can power with the engine slightly "off" if you are heeling, etc.

It's not a solution for non-zero angle installations; it's a solution for the wear and tear normal operations can impose on transmissions, shafts and so on.

I personally also got it because the coupler and the thrust bearing and the soft mounts cut vibration and allow shifting of a Variprop to happen without godawful shocks to the transmission...CLUNK! CLUNK!

[S/V Alchemy]

Originally Posted by James S

I don't recall the brand, but when I looked at CVs it seemed like they were quite long...the one I was interested in also managed thrust...the assembly was fixed hard to a small bulkhead of sorts...seems like the whole thing was around 17inches long, of something crazy like that..

Not quite. Here's my friend's steel ketch installation, which will closely resemble mine when I'm done.

The engine's a Volvo 55


The Aquadrive and thrust bearing.





My buddy said it took him a considerable amount of fiddling around to get everything dialled in, but the result is that you can barely hear or feel the engine underway.

[Blue Stocking]

CV joints usually have 1/2- to-1 degree out of plane to facilitate lubrication of the contact surfaces.
X type universal joints are about 3 degrees.

[James S]

Nice clean looking installation on your buddies boat S/V Alchemy his engine is 55hp if I'm correct....the CVB 10.10 is about the size he would need...thats about 10 or 11inches long.
The smallest Aquadrive that's fits the rated horsepower of the OP's 135hp would be the CVB21.10 that's somewhere between 13 to 15inchs long depending on the trans coupling.
This is still fairly long IMHO.
Not saying its not an excellent bit of kit...it may be, I'm just saying it may be long for some applications.

[stillbuilding]

Originally Posted by S/V Alchemy

I am shortly installing an Aquadrive on a steel motorsailer. My understanding is that a "few degrees of misalignment" is to be avoided: You install the engine on soft mounts and get the thrust bearing perfectly lined up along with the shaft coupler, Aquadrive and engine side, and then you can power with the engine slightly "off" if you are heeling, etc.

It's not a solution for non-zero angle installations; it's a solution for the wear and tear normal operations can impose on transmissions, shafts and so on.

I personally also got it because the coupler and the thrust bearing and the soft mounts cut vibration and allow shifting of a Variprop to happen without godawful shocks to the transmission...CLUNK! CLUNK!

Thanks for that response. My gut feeling was to go for perfect alignment but many people seem to be suggesting that 1 - 2 degrees is necessary for the drive!!?? The thrust block component is one of the reasons I have considered this option. In fact, when funds permit I intend to move to a four blade Variprop also. Nice prop.

[stillbuilding]

Originally Posted by James S

I've not used CVs Richard...and not sure how big/heavy an engine you can go with flex mounts.
I can tell you that you can get a lot of noise through your exhaust system.
I isolated pretty much all I could with rubber mounts...it brought the "rumble" sound down quite a bit.

James,
Beautiful installation as I would expect from you.
Soft mounting of everthing seems a very high priority. I have considered a muffler after the waterlift. Did you look at that possibility?

[stillbuilding]

Originally Posted by Blue Stocking

CV joints usually have 1/2- to-1 degree out of plane to facilitate lubrication of the contact surfaces.
X type universal joints are about 3 degrees.

Thanks for the response. This is what many contacts have noted. Does "usually" = "should"? Can build in 1 degree of misalignment of course. This still seems consistent with the above comment that the function of the drive is to simple protect the transmission components. Having had leaking oil seals from transmission alignment problems in the past this makes the drive attractive. Is the CV drive likely to help with noise suppression (apart from the clunk of prop engagement mentioned above)?

[Blue Stocking]

I have been an interested on-looker at 2 installations, from different manufacturers.
Each gave specific max/min alignment figures.
My understanding is that the "offset" is not a balance problem, but is to create varying movement on the contact faces of the male/female halfs to cause the ball bearing to rotate and self-lubricate.
A 3 shaft assembly apparently does not require the offsets of 2 CV joints to be similar angles of input and departure.
Any car builders will tell you that this is not the case with the drive train using x- type universals, which must be similar angles.

[delmarrey]

I installed the Pythondrive because it was shorter then the Aquadrive. I like the Aquadrive shaft coupling better but they are almost the same other then that. They do need a 2-4º misalignment per joint (total 4-8º).

I have a small Yanmar (3JH4E) that shakes real good at an idle (soft mounts) so I went with the CV system. And it does quiet it down quite a bit and so far runs real good. I was having trouble with my shaft seal (PSS) chattering causing it to leak a bit. But since I installed the CV's it's smoooth as silk.

I did have to move the motor forward about 3" and change the angle (more level now) but well worth it!

I might add; I keep the boat on the had most of the time, the alignment changes between the the hard and water, so I no longer have to worry about shaft misalignment between the two surfaces.
.

[stillbuilding]

Originally Posted by delmarrey

I installed the Pythondrive because it was shorter then the Aquadrive. I like the Aquadrive shaft coupling better but they are almost the same other then that. They do need a 2-4º misalignment per joint (total 4-8º).

I have a small Yanmar (3JH4E) that shakes real good at an idle (soft mounts) so I went with the CV system. And it does quiet it down quite a bit and so far runs real good. I was having trouble with my shaft seal (PSS) chattering causing it to leak a bit. But since I installed the CV's it's smoooth as silk.

I did have to move the motor forward about 3" and change the angle (more level now) but well worth it!

I might add; I keep the boat on the had most of the time, the alignment changes between the the hard and water, so I no longer have to worry about shaft misalignment between the two surfaces.
.

So does that mean 4 degrees minimum for all installations?

Sounds encouraging re the noise issue. Had not considered changing shaft alignment issues when slipping but could be a bonus.

[S/V Alchemy]

Originally Posted by Blue Stocking

CV joints usually have 1/2- to-1 degree out of plane to facilitate lubrication of the contact surfaces.
X type universal joints are about 3 degrees.

That's news to me which I will have to verify.

Luckily, it's not hard to arrange!

[S/V Alchemy]

Originally Posted by James S

Nice clean looking installation on your buddies boat S/V Alchemy his engine is 55hp if I'm correct....the CVB 10.10 is about the size he would need...thats about 10 or 11inches long.
The smallest Aquadrive that's fits the rated horsepower of the OP's 135hp would be the CVB21.10 that's somewhere between 13 to 15inchs long depending on the trans coupling.
This is still fairly long IMHO.
Not saying its not an excellent bit of kit...it may be, I'm just saying it may be long for some applications.

That's true. I'd forgotten about the different sizings...I'm installing a Beta Marine 60 and we ordered two of the same size as we have pretty close specs on our boats.

As I have a modified full keel and a zero-degree installation (the shaft goes out at zero degrees, I have plenty of room to play with, although I will have to weld in a stringer where none currently exists.