Replacing the Original V-Drive
The Walter RV-20 V-Drive is the last piece of the original drive train on Sarah, except for the propeller shaft.  I replaced the Westerbecke engine and the Paragon transmission in 2008 with a Yanmar engine and a Velvet Drive transmission.  The original propeller was replaced with a Maxprop in 2003.  The V-Drive was re-built in 2000, shortly after I purchased Sarah.
This spring (2010) when I moved Sarah from New Bern, NC to Oriental NC for a haulout I noticed more than normal vibration when under power.  I had noticed this the previous winter in the Bahamas, but it appeared to grown more severe.  The Deaton yard in Oriental tried to re-alighn the propeller shaft to the V-Drive with only limited success.  On the way back to New Bern the vibration was still there.  Although this vibration might be the result of a bent prop, I cannot recall any incident in the past 5 years that could have caused the damage.  I have observed every haulout in that time and boat was never picked up, even briefly, on the prop shaft.  That is probably the most common source of shaft damage on these boats.  I also cannot recall in that time ever striking an object with the drive train.  If the shaft is bent, it likely happened more than a few years ago.  The noticeable vibration is a recent phenomenom. 
So, although the V-Drive has not been proven to be the source of the vibration, I have decided to replace it.  It is 30 years old and long out of production.  The cases are cast iron and cannot be replaced except by scavaging a unit that has been removed from another boat.  It is time.
Removing the RV-20

Original RV-20 V-Drive
So on June 1, 2010 I moved Sarah back to Deaton Yachting Services and initiated the process of replacing the RV-20 with the current model, RV-26.  The first job was to remove the old RV-20.
In the picture on the left the V-Drive has been de-installed and is ready to be removed from the boat
On of the things that I expected to be changed for the new V-Drive, which is larger, is the seawater manifold I installed to provide cooling water to both the main engine and the generator.  The raw water strainer for this manifold is mounted on a wooden support at the forward end of the pan under the V-Drive.  Fortunately Deaton's was able install the RV-26 without requiring a change to the plumbing.
Space Previously Occupied by the RV-20

Propeller Shaft and Shaft Seal
In the view on the left you can see the propeller shaft.  The flange on this shaft must be replaced with one for the RV-26.  Getting this flange off the shaft should be one of the more challenging tasks in this installation.
You can also see moisture running from under the engine pan past the pilot tube.  Yep, my rudder stuffing box is leaking again.  Bilge pump comes on every 2-3 days for about 30 seconds.  Not a lot of water, but I'll use the opportunity of being in the Deaton Yacht Services yard to have one of their munchkins tighten or re-pack the stuffing box.
Here is the V-20 in the shop after being removed.
An Old and Rusty RV-20
Photo by Deaton
Installing the RV-26 

Original RV-20 Jackshaft
Photo by Deaton
This is the jack shaft that connected the RV-20 to the tansmission.  The original plan had been to re-use this jack shaft with the RV-26.  This required a new U-Joint (seen at the left end of the shaft) for attachment to the RV-26.
It turned out to not be practical to use this jack shaft.   Although the length of the jack shaft is adjustable (the spline shaft on the right end can slide into and out of the outer tube) this shaft could not be shortened enough to fit between the transmission and the newly installed RV-26.  After the yard fought with this issue for several days I finally bit the bullet and ordered a shorter jack shaft from Walter.  This was a very expensive bullet to bite.
The new RV-26 waiting on the installation.
New RV-26, Ready for Installation
Photo by Deaton
Photo by Deaton
The serial number plate on the RV-26.
Before RV-26 could be installed, new mounting backets were made and painted.
New Mounts for the RV-26
Photo by Deaton

Installing the New V-Drive Mounts
After the old V-Drive had been removed the new mounts were installed.
Then the V-Drive came onboard.  
Fitting the RV-26 Onto the Mounts

New RV-26 and New Jackshaft Installed
This pictue shows the completed installation of the RV-26 and the new jack shaft.  I had left Sarah at Deaton for over 2 months while I was on the delivery of a 54' Bertam Sport Fisherman.  After the installation was complete, but while I was still on the delivery I had Deaton cut a new hatch in the cabin sole just aft of the hatch over the V-Drive. 
Now I have almost unrestricted access to the PSS Shaft Seal and the jack shaft.  I'm sure the installers at Deaton would have appreciated this access if it had been available during the RV-26 installation.  
Access to Drive Train Through New Hatch in Cabin Sole