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Old 22-07-2012, 16:34   #61
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Re: The Blonde Zinc Replacement

Abou to stir up some more fun... But I like using loctite on zincs (except shaft zincs). While its great at keeping the parts together, it is also great at acting as an insulator. Exacally what you don't want in a anode system.
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Old 22-07-2012, 16:34   #62
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Re: The Blonde Zinc Replacement

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Originally Posted by LeaseOnLife View Post
The loctite 248 works underwater because it is a paste. The 'normal' blue loctite 242 is a thin fluid and washes away too easily in the water.
Not so. There are many Loctite stick "paste" products that do not perform when used underwater. 248 works because it is a special formulation.
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Old 22-07-2012, 17:19   #63
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Re: The Blonde Zinc Replacement

Here is the e-mail I received from the makers of Loctite when I asked them what product could be applied to parts topside and safely used on said parts when assembled underwater (other Loctite products can be used underwater, but must be first assembled and allowed to cure above water, which is obviously problematic when replacing anodes underwater):

From: richard.e.avery@us.henkel.com [mailto:richard.e.avery@us.henkel.com]
Sent: Monday, March 05, 2012 7:16 AM
To: Matt Peterson
Subject: RE: Henkel Inquiry - Case #: 00083412 [ ref:_00D301RJ1._50080IRF10:ref ]


If I am understanding you correctly, then this will not work. Loctite 243 will not cure unless it is between two pieces of metal and restricted of air, hence the name anaerobic. It will remain a liquid if you coat the bolt and just let it sit in open air. If you need a threadlocker that can be applied underwater, you will need to use Loctite 248 Quickstix or Loctite 249 Quicktape.

Regards,

Rick Avery
Technical Engineering Representative
Henkel Corporation | AG Industrial Products
One Henkel Way
Rocky Hill, CT 06067
United States
Home - Henkel North America

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Old 22-07-2012, 17:31   #64
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Re: The Blonde Zinc Replacement

Well I've been playing Mr. Wizard, Er well Miss Wizard today. So after failing to find the millivolt readings in fresh water on line. I went topside and got a bucket of river water. I put some in a clean plastic storage container and placed a stainless steel wire clamp and my bronze deck key in the water and measured the potential differential.. Got 300 millivolts which is pretty good.

Then dug up one of my spare zinc's and placed it in the water with the stainless steel bit and read 1100 ish millivolts. Wow.

Went back below and started cleaning the 40 year old bronze wingnut that my wire is connected too. Now I get about 110-120 millivolts. I expect the bronze rod and the zinc is friction tight on now has got some of that 40 year old corrosion on it too.

So once the zinc corrodes enough for me to pull it out, I'll take some sandpaper to the bronze bits. I'm even thinking of bonding a wire to the zinc and installing a threaded connection through the cap (water proofed of course). Gee I might get some aluminum rod from the hardware store and make some aluminum anodes to fit the basket.

In my on line surfing, I found that 50 feet is the maximum length of an anoid wire, above which no voltage is possible. The shorter the wire the better.

Will let you know how the blonde zinc works after a few weeks.... Or when my prop fails..

Now back to the thread compound discussion,
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Old 22-07-2012, 19:08   #65
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Re: The Blonde Zinc Replacement

Chic-- are you attempting to use the zinc in a bucket as a reference half cell?

Anyway, I long ago gave up totally on zincs. In fact, on my old Hunter 30 sailboat, I never used an anode. When I sold it after 25 years of usage, there were no signs of galvanic corrosion.

My current boat is a different matter. I use aluminum anodes, no, make that one (1) anode mounted on the boat's stern...in the water of course. Further I made 2 shaft brushes using oil impregnated sintered bronze that ride on each prop shaft to get better bonding than possible through the transmission's oil. And yes, it does bother me that I had to resort to an oil impregnated hunk of sintered bronze. I first tried using just pieces of bronze which wore unbelievably fast just resting on the turning shafts.

Finally, I measure the voltage between wetted bonded points using a silver-silver chloride half cell I was lucky enough to purchase on Ebay for less than $50. I measured last -0.76 on my SS shafts which is fine.

The readings should be less positive than -750mv for SS, -550mv for bronze and -800mv for mild steel when using a silver silver chloride half cell. Anything other than measurements is just plain guess work regardless of who the expert is.

Foggy

EDIT: The reference half cell can be other metals beside what I used. The advantage of using a known standard is there are published numbers of acceptable readings for various metals.
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Old 22-07-2012, 19:25   #66
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Re: The Blonde Zinc Replacement

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Originally Posted by sailorchic34 View Post
Gee I might get some aluminum rod from the hardware store and make some aluminum anodes to fit the basket.

Now back to the thread compound discussion,

Now I know you're joking about making your own aluminum anodes because they consist of a mixture of metals that form an alloy. But a good thought anyway!

Foggy
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Old 22-07-2012, 20:43   #67
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Re: The Blonde Zinc Replacement

well Sort of... I figured its worth a shot. Ha good to know about the splintered bronze, as I was going to try brass strips on the shaft.

yes it is sort of guess work, though having a millivolt readings and comparing to published numbers for stainless and zinc least puts me in the ballpark. Though I don't know the type of stainless so yes its a bit of a wag..

Besides a -150 millivolts to the zinc in the seastrainer is better then nothing at all. which is how it would sit otherwise... Still got the old brain thinking about other options. I'm just a bit annoyed that the zinc was missing on the shaft...

Not to mention that my underwater skills are sorely lacking. Probably because I learned to swin in a lake outside Rudyard, Mi in june some time ago. Cold water up in the U.P. of Michigan in the summer. Of course learning to swim entailed splashing around for 5 minutes till your lips turned blue.
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Old 22-07-2012, 21:39   #68
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Re: The Blonde Zinc Replacement

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Now I know you're joking about making your own aluminum anodes because they consist of a mixture of metals that form an alloy. But a good thought anyway!

Foggy
As far as I know, the anodes in domestic hot water tanks are available in different formulations and you might be able to get the right alloy. You might also find the right stuff with suppliers specializing in anodic protection.
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Old 22-07-2012, 22:16   #69
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Re: The Blonde Zinc Replacement

I thought about a water heater anode, Those generally are magnesium and come with a 3/4" threaded bronze plug.. Would work for the fresh water I'm bouncing around in now. but they are too reactive for salt water..

Most of the Aluminum anodes are alloys of aluminum also, about 95 to 99 percent aluminum, so I need to do a bit more research there. Maybe I can recycle my aluminum diet soda cans....;-)
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Old 22-07-2012, 22:28   #70
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Re: The Blonde Zinc Replacement

The proper alloy for aluminium anodes is MIL-A-24779

With the following recipea

*Zn- min. 4.00% - max. 5.00%
*In- min. 0.015% - max. 0.020%
*Si- min. 0.080% - max. 0.120%
*Fe- max. 0.090%
*Cu- max. 0.003%
*Others - max. 0.100%

The absolutely critical issue is the iron. Any more than spec can lead to a massive reduction in protection. Sadly cans run around .7 Fe.
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Old 22-07-2012, 22:38   #71
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Re: The Blonde Zinc Replacement

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Originally Posted by sailorchic34 View Post
I thought about a water heater anode, Those generally are magnesium and come with a 3/4" threaded bronze plug.. Would work for the fresh water I'm bouncing around in now. but they are too reactive for salt water..
The magnesium anodes only work in hot water as far as I know but I am pretty sure you can get specialty aluminum anodes. I am not sure what they are used for but I am pretty sure they are available. Apparently zinc is less noble than steel in hot water hence standard zinc is (less than) useless in hot water.
Even if standard heater anodes are not available in the right alloy for your use, we are talking about a VERY common application for fresh water protection and you can use standard zincs for salt water use.
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Old 23-07-2012, 17:28   #72
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Isn't the easy solution to the prop anode falling off, is to paint the area around the attachment points? Another I read somewhere was to dab a bit of silicone to do the same. The silicone could also do the job of loctite, maybe. I haven't tried either as yet but will do at my next replacement date, currently every 2 months!
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Old 23-07-2012, 19:16   #73
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Re: The Blonde Zinc Replacement

I kind of like your idea of a zinc that can be changed from inside the boat. I don't have any anodes on my prop and shaft. All metal on my boat that touches the water is connected electrically to a large zinc plate mounted on the hull. It seems to work. The zinc goes away and nothing else. It sure would be nice to be able to change the zinc without getting wet or hauling.
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Old 23-07-2012, 19:44   #74
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Re: The Blonde Zinc Replacement

I've been looking at my 2" copper standpipe. I keep thinking replace the 2" elbow with a 2" tee and get a 6" ish long 1/2" or 3/4" diameter zinc's. That should work too. My raw water line is 5/8" so the inlet is oversized.

As would a seachest with a 1" seacock and 1" diameter zinc. A spare unused seacock could also be used.. Using #10 wire for bonding and maybe a splinter bronze strap for the prop shaft and away you go..

Maybe I should put together a kit... Though it's just bits and pieces...
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Old 23-07-2012, 20:27   #75
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Re: The Blonde Zinc Replacement

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I kind of like your idea of a zinc that can be changed from inside the boat. I don't have any anodes on my prop and shaft. All metal on my boat that touches the water is connected electrically to a large zinc plate mounted on the hull. It seems to work. The zinc goes away and nothing else. It sure would be nice to be able to change the zinc without getting wet or hauling.
What? You're in Miami and worried about getting wet?

You do know that there are people from far away places that pay good money to come to Miami and jump in the water?

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