PDA

View Full Version : Is there a need for sacrificial anodes in fresh water?



Endurance
04-07-2015, 04:50 PM
Other than the sacrificial anodes on my outboard motors, my aluminum pontoon houseboat has no zincs. It is in fresh water and the only salt water it will experience is in an ice cream maker in the galley.

Is there any reason for me to have sacrificial anodes?

OLD HOUSEBOATER
04-07-2015, 05:06 PM
If you get into a situation where the shore power is "dirty" or dockmates have electrical problems you'll wish you had them.

easttnboater
04-08-2015, 06:24 AM
What OHB said. I was in one of the cleanest lakes in the country - South Holston in NE Tennessee - and after three years, the anodes on my Bravo IIs were half gone.

GoVols
04-08-2015, 06:48 AM
Zinc anodes do not work in fresh water. You MUST use magnesium. I bought new ones from boatparts.net and replaced mine last year.

easttnboater
04-08-2015, 12:08 PM
Got mine at boatzincs.com. Anodes is the proper term - come in zinc, magnesium, and aluminum. But "zinc" is used as the generic term for anode. And, yes, I used magnesium.

Endurance
04-08-2015, 01:18 PM
Thanks, all. That's kind of what I thought. Like easttn, I use "zincs" in the generic sense as a shorthand for sacrificial anodes. Kind of ironic that for fresh water, a good portion of the recommended zincs for my aluminum hull will be made of aluminum.

Even though my boat pretty much never plugs into shore power and I am on a buoy rather than a dock and the neighbors I would have on a dock, I think I'll add some anodes. After all, they're cheap. It looks like I'll be buying an alloy of magnesium and aluminum. I was thinking that having anodes could never hurt until I came across this tidbit:

"It is not recommended to use magnesium anodes in salt or brackish water. The result may be an accelerated corrosion rate . . . ."

The wrong zincs can accelerate corrosion. Ouch!

OLD HOUSEBOATER
04-08-2015, 01:39 PM
Zinc anodes do not work in fresh water. You MUST use magnesium. I bought new ones from boatparts.net and replaced mine last year.

Boaters have been using Zinc in fresh water since before Magnesium. Had them on every boat I ever owned. Magnesium is a late comer to the game, They are better and can be smaller for the same amount of protection.

GoVols
04-09-2015, 07:22 AM
When I received the magnesium anodes I ordered, they had the word "zinc" cast into them. Furious, I called the site I ordered them from and told them they screwed up my order. They called the manufacturer to ensure they were made of magnesium and they confirmed it was the correct parts. For some stupid reason, the company uses only 1 die to make both material products. They told me to weigh the parts to confirm, which I did, and they were the correct weight.

Ike
04-28-2015, 04:26 PM
Simple answer yes. Not only will electrical currents in the water cause problems, polluted water will too. On the lake where I do my fishing, there is a lot of runoff from lawns and gardens. These fertilizers can react with aluminum. Every year, by the end of the season I have little white nodules all over the sterndrive and outboard. If I didn't have anodes on those I would have a serious problem. Even so I still have to clean it up every so often during the year.

Amelia
04-29-2015, 06:58 AM
So, sometimes, especially late in a dry summer, my little corner of the swamp is brackish. The rest of the time it's fresh. I do have hopes of getting as far as real salt water in a few months, though, when Our Hero retires...again. So, we should use magnesium anyway on our outboards?

BananaTom
04-29-2015, 03:52 PM
SI do have hopes of getting as far as real salt water in a few months, though, when Our Hero retires...again.

Where are you dreaming of?