Rudder / shaft anodes?

"So far I've read from 1/4" to 1" which is quite a big difference."

I'm think'in much closer to 1". That's about exactly what Willy's got.

manyboats said:

I'm think'in much closer to 1". That's about exactly what Willy's got.

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How's about we average it out to about 5/8's of an inch? I didn't mount the zinc flush to the prop because it was hand cut with a hacksaw and isn't perfectly perpendicular to the shaft...good idea?

(Bonus shot of the transom plate that's connected to the shaft brush)

Murray do you have a shaft seal that has water taken off the seawater elbow feed? If so 1/4" would probably be enough but I'm not sure. I would think 5/8" would be plenty for a water fed stern tube and probably for a static one too but I think it's a little questionable. Probably fine .. just don't want to put a personal blessing on it. Lets see what others think.

I walked through a boat yard a couple of years ago with my multimeter and checked the continuity of anodes on about 40 boats. Only two boats had any continuity at all. One had just had a new anode installed on a properly prepared shaft and one was a brand new boat that had never been in the water.

Anodes can look near new and be doing absolutely nothing. I suggest checking all your anodes for continuity no matter how good they look. You should see a maximum of 1ohm. Photo below shows a not bad looking anode showing O.L. (open line = no continuity) with the shaft.

boatpoker said:

I walked through a boat yard a couple of years ago with my multimeter and checked the continuity of anodes on about 40 boats. Only two boats had any continuity at all.

Photo below shows a not bad looking anode showing O.L. (open line = no continuity) with the shaft.

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Photo also shows a cheap consumer grade meter set on megohms. That meter has a resolution of 1K ohms in the lower megohm range and 10K at its higher range.

It is not being used properly and is worthless for that application in any event.

That being said, you are correct that continuity between the zinc and the protected material is important. A zinc (especially a cheap Chinese zinc that may contain iron contamination) will develop an insulating oxide layer that essentially stops it from working.

RickB said:

Photo also shows a cheap consumer grade meter set on megohms. That meter has a resolution of 1K ohms in the lower megohm range and 10K at its higher range.

It is not being used properly and is worthless for that application in any event.

That being said, you are correct that continuity between the zinc and the protected material is important. A zinc (especially a cheap Chinese zinc that may contain iron contamination) will develop an insulating oxide layer that essentially stops it from working.

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You are incorrect. There is no Megohm setting. It is an autoranging meter. The megohm symbol is random when there is no continuity. You can see the "AUTO" in the top left portion of the screen.

Please also note that I never used the word "zinc" as it's hard to tell if its zinc, aluminum indium or magnesium after its scaled up. I always say "anode" uinless I am positive otherwise.

Please explain why a multimeter is wortheles in this application. Continuity is simply continuity !

manyboats said:

Murray do you have a shaft seal that has water taken off the seawater elbow feed? If so 1/4" would probably be enough but I'm not sure. I would think 5/8" would be plenty for a water fed stern tube and probably for a static one too but I think it's a little questionable. Probably fine .. just don't want to put a personal blessing on it. Lets see what others think.

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What? Think I've got a fiercely aggressive law firm waiting to pounce

I'm waaaaay down at the bottom of the learning curve here, but our shaft seal looks as simple as it gets, but robust.

Here's a photo below, and the photo below that is the equally robust shaft brush;

Interesting hose clamps. I'd consider changing those out, but they do appear to be functioning. The standard for that kind of set up is dual t-bolt clamps. The packing box hose looks a tad suspect as well. I only say that because I can't see multi-plys on the end cut.

It looks like you have some kind of ground that may or may not be attached at the shaft log. The yellow crimped on the white wire thingy. Might want to check and see what it is supposed to do.

Here's the 'after' Murray.

Thanks NS and Chip,

Our intentions in this first year are to make no major changes. Next year, after some actual experience and more opportunities to sponge information, we'll start swapping things out with "industry standard" parts or upgrading things.

The PO was a structural engineer, so should have had a good understanding of forces, tolerances, and appropriate components to contain and/or control said forces. Will keep my eyes on things though...

Chip, does your bilge still look that pristine!??!

Yes. I get no water in the bilge now that the Gore packing has seated in. Sometimes when I remove the big Bomar hatch in the rear cockpit some trapped water around the seal with drip down and drain through.
But I'm anal and promptly wipe it up.
I dry boat is a happy and fresh smelling boat.

Anode,
In post #39 How does the grease get into the inner brng and how is the shaft attached to the inner race?

manyboats said:

Anode,
In post #39 How does the grease get into the inner brng and how is the shaft attached to the inner race?

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Eric - There is a 'grease groove' machined in the outside of the outer race with a hole to allow grease into the inner bearing.
Not in the picture is a split tapered threaded collar on the shaft that slips between the shaft and inner bearing. The nut and lock washer lock it down.

Anode,
Yes I was guessing about the same on the grease
The "thread collar" must be incredibly thin or I don't understand. Suspect the not understand is more like it.