Repair of surface pitting on saidrive

[sowwaninii]

Changed all zincs on my SD 50 end of October and now 2 months later split ring zinc on SD totally gone with some surface pitting of leg. Suspect one marina we visited was hot. Now need to haul boat and repair to prevent further damage. Any recommendations would be appreciated. Btw, am having an electrical survey performed. Also noticed that the Yanmar “zinc” was aluminum, but the flexofold is truly zinc.

[Ostinato]

Using zinc and aluminum anodes together is not recommended from what I read. I did it too because my new sail drives came with aluminum and almost immediately started seeing problems. I now have all zinc because I couldn’t find aluminum anodes for my props. It also made me haul early.

On my previous sail drives for pitting I cleaned the aluminum until I reached bare metal. I found my sail drive casing quite thick.

Then without delay I coated the pits with west expoxy. Next before that set up I coated again with west epoxy mixed with a non water absorbing filler such as micro fibers. International said I should next coat this with their epoxy barrier paint since “nothing will stick to it” according to them. Finally I painted it with primer and anti fouling.

It lasted several years until I changed drives. The only down side I found was the epoxy is brittle and if you hit it by error, it can chip. Good luck.

[Bill O]

Depending on the depth of the pitting, would probably use a Devcon putty filler instead of West or similar.

We used the Devcon Aluminum putty on the our aluminum bow sprit edge before repainting. While somewhat expensive, it was easy to use, stayed in spot on a vertical surface, sanded well and was tolerant of lower temps. After several years it still looks good.

I think the aluminum putty is only water resistant, but they do make a specific underwater repair putty that would work for your application.

Bill O.

[sowwaninii]

Thanks. Will check out the underwater repair version.

[sowwaninii]

Thanks for the advice. Assume replacing drives was for other reason than corrosion?

[Ostinato]

Yes it was. 2000 hours and they were shot. After pushing ZF they finally agreed sell to me parts but they were more expensive than a new drive. Then they said they had answered as many of my questions as they were going to. Finally in frustration I went the Canes boat show to talk to a rep directly. Got a VP who told the sail drive servicing hours and later put it in writing. Essentially the ZF10s were at end their life and I turned to Twin Disc.

[sowwaninii]

2000 hours seems way too short for saildrives to die. Pretty disappointing

[Ostinato]

Yup it is. What went initially were the output (prop) shafts. They groved to the point where new seals would not stop sea water from entering. The VP. told me they were only good for 1400 hrs. Next to go he said would be the clutches in what is essentially a Hurth transmission.

He said if the boat had been in charter service I would have been lucky to get 1200hrs out of them. I have had experience repairing Hurth clutches before and didn’t want to do that again.

When we pulled the drives the upper shaft seals were gone too and leaking oil on the flywheel. So I was glad I made the decision to dump them.