Re: [Amel Yacht Owners] Re: Prop Shaft Electrolysis


Olivier Beaute
 

Good evening Derick and Kent,

Everything Kent describes is OK. The bolt that holds the foot is set into a tapped hole into the cast iron ballast (no insert). After some years (say 5), the foot should be checked by shaking sideways. If it moves, it's time to replace the rubber sleeve and washer.
This is when you're surprised that the bolt comes out quite easily. The secret (no secret for a good mechanic) is... GREASE ! This also means the bolt could come out easily from itself (because of vibrations). The answer is, once the bolt is set and tight, to cover its head with black silicone compound (filler).

Kent, I wish you good luck for the final job.

Olivier.



On Wednesday, April 8, 2015 9:21 PM, "Kent Robertson karkauai@... [amelyachtowners]" wrote:


 
Hi Derick.
The lower part of the CDrive (I'll call it the "foot") is actually mostly composite, with embedded metal (I don't know if it is aluminum or steel) where the 90 degree gear is that goes from the vertical shaft to the prop shaft. It only weighs about 75lbs.  The bolt that goes thru the foot into the keel extension is close to 6 inches long and screws into the keel where I think there is an embedded nut or tapped steel plate.  It doesn't go through the keel.  There is a rubbery washer-type seal that goes around the bolt between the foot and the keel.  Not a watertight seal by any means, but my original bolt seemed to be in pretty good shape for being 16 years old...there was some rust on the threads.  It turned out of its hole without difficulty.

Half of the vertical shaft is in the foot and has a female upper end with splines.  The upper half is part of the upper assembly and drops through the hole in the hull into the hole in the top of the foot.  A rubber boot seals the hole in the boat with two large hose clamps at the level of the lip that protrudes into the hull around the hole, and two more at the level of the upper portion of the drive.

Three large o-rings seal the connection between the foot and the upper drive.  The upper half of the vertical shaft is splined to fit into the top of the lower half in the foot.

Exactly how the foot is designed inside is unclear, I never tried to disassemble it.

We'll be installing it again tomorrow (for the last time, I hope).  I'll take a lot of pics and post something in the files section that should make it clearer.

Kent
SM243
Kristy


On Apr 8, 2015, at 2:01 PM, derickgates@... [amelyachtowners] <amelyachtowners@...> wrote:

 
Kent,
 
In thinking about your current task, I have been studying the diagram in the Files section that shows how to disassemble/assemble the C-drive.  Among the things that are not clear to me is exactly what parts stay with the boat and what parts make up the "lower end".  In documenting your assembly process, could you be sure to show pictures of the meshing of the two pieces?
 
Also, how long is the bolt that you are drilling the hole for in the foot of the C-drive housing?  The diagram makes it look fairly short, but perhaps the diagram does not show the length of the bolt to scale.  Does the bolt screw into a nut embedded in the keel, or does it completely penetrate the keel and the nut is on the bottom of the keel?  I assume that waterproofing this bolt hole is important to prevent rusting of the keel iron.  Have you observed how the inside of the bolt hole (the part in the keel) is protected from water/oxidative corrosion?
 
We are all pulling for you in the hopes that all goes smoothly.
 
Derick
 
SM2K #400 Brava
Currently in Sapphire Beach Marina
(While I am stuck in Massachusetts)


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