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Old 20-07-2016, 23:51   #1
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Any DIY portable anodes to prevent galvanic corrosion?

anybody ever hear of anyone making a temporary sacrificial zinc setup on their boat? The marina didn't change my zincs, and they are shot. I wanted to not have to be without the boat for a few days, which would be the case of I left it off to them to do. I have twin mercruisers with alpha drives. Could I connect a wire to each block and put a zinc on the other end and chuck it overboard while sitting at the dock? Do I have to tie into the onboard electrical system? If so, the 12 V d/c or the 110 V a/c system?
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Old 21-07-2016, 00:25   #2
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Re: Any DIY portable anodes to prevent galvanic corrosion?

You have to make an electrical circuit between the zincs and the metal parts in the water you are protecting. If it is the stern drives you need a wire between the zincs and the part hanging in the water with the zincs hanging in the water next to them. You do not need to connect to any electrical systems at all.
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Old 21-07-2016, 07:02   #3
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Re: Any DIY portable anodes to prevent galvanic corrosion?

...But why not just hire a diver to swap out the zincs? They do it all the time.
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Old 21-07-2016, 07:13   #4
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Re: Any DIY portable anodes to prevent galvanic corrosion?

There's a reason outdrives have so many anodes mounted in so many places. Hanging an anode overboard and wiring it to the engine block will almost certainly not get the job done.
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Old 21-07-2016, 07:53   #5
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Re: Any DIY portable anodes to prevent galvanic corrosion?

Grab a mask and snorkle and change them in the water if you don't want to haul the boat. I find a shallow, sandy anchorage and do it during low tide so I can stand up. Plus it's easier if I drop a bolt or nut. I still keep a box of spare hardware in case I do loose a bolt, nut or washer.
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Old 21-07-2016, 08:13   #6
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Re: Any DIY portable anodes to prevent galvanic corrosion?

Outdrives you can back up close to shore and sit on the bottom and change them, I doubt you would even need a mask, usually they tilt up quite a lot.
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Old 21-07-2016, 08:24   #7
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Re: Any DIY portable anodes to prevent galvanic corrosion?

Better a temporary home-made anode than no anode....

Chunk of the desired anode metal and a drill... bolt it on, ensuring good contact to the metal you want protected.
Then the anode just has to be submerged to work.

I wouldn't do it by hanging the anode on a wire.
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Old 21-07-2016, 08:26   #8
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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Outdrives you can back up close to shore and sit on the bottom and change them, I doubt you would even need a mask, usually they tilt up quite a lot.
The Alpha's might easier. My Bravo III drive is completely underwater and doing it without a mask and snorkle would be possible, but not efficient.
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Old 21-07-2016, 08:27   #9
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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Better a temporary home-made anode than no anode....

Chunk of the desired anode metal and a drill... bolt it on, ensuring good contact to the metal you want protected.
Then the anode just has to be submerged to work.

I wouldn't do it by hanging the anode on a wire.
Bolt it on to what? His outdrives?
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Old 21-07-2016, 17:32   #10
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Re: Any DIY portable anodes to prevent galvanic corrosion?

We rigged the following: Alligator clips, copper wire--4-6 gauge--, zinc plates. Made four sets, each long enough to go 4 feet into the water, clipped to the lower shrouds, both sides. Used them in foreign ports where stray currents made things dicey.
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Old 21-07-2016, 18:04   #11
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Re: Any DIY portable anodes to prevent galvanic corrosion?

That sounds like my next intermediate step.
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Old 21-07-2016, 20:09   #12
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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We rigged the following: Alligator clips, copper wire--4-6 gauge--, zinc plates. Made four sets, each long enough to go 4 feet into the water, clipped to the lower shrouds, both sides. Used them in foreign ports where stray currents made things dicey.

Reed, does this protect your prop? Are the shrouds grounded to the block/shaft? I am eating through zincs too fast so looking at options till I leave the marina.


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Old 22-07-2016, 15:02   #13
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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I am eating through zincs too fast so looking at options till I leave the marina...
Is your power connected? If so, do you have a galvanic isolator?

To the OP. I have a hanging anode that I connect to my saildrive, it must connect directly to the bit of metal you are trying to protect.
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Old 22-07-2016, 15:37   #14
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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Is your power connected? If so, do you have a galvanic isolator?



To the OP. I have a hanging anode that I connect to my saildrive, it must connect directly to the bit of metal you are trying to protect.

No AC or charger (other than solar) on the boat, so I'm pretty sure it isn't me. I blame the commercial boats.

I will have to rig something up that can connect to my prop and hang off the side. How to connect to the prop easily is where I am stuck. A bit out of arm reach without getting completely wet.


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Old 23-07-2016, 06:23   #15
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Re: Any DIY portable anodes to prevent galvanic corrosion?

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...I'm pretty sure it isn't me. I blame the commercial boats.
In all likelihood, the problem is aboard your boat, not the neighbor's. You need to have an electrician find (and fix) the problem rather than looking for a band aide or pointing fingers.
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