Zinc or Aluminum Anodes

[JeffreyAC77]

We keep our R31 in fresh water (Lake Union) but get out on the sound for probably 45+ days each year. Which way is best for the anodes? Thanks.

 

[RichBirk]

Aluminum, good for fresh or salt water. Keep in mind many areas of Puget Sound are brackish, as fresh water from storm runoff floats on top. In addition, we trailer our boat and find that aluminum oxide is much softer and easier to clean up after drying than zinc oxide. My opinion only

 

[dbsea]

+1 for Aluminum. I keep my boat in Portage Bay and go the salt often. The aluminum has been holding up well for me. Recommend you add a galvanic isolator as well if your boat doesn't have one already. 🙂

 

[scross]

I try to use aluminum as well. Unfortunately, I wasn’t able to find all of the zincs with aluminum that my old boat (R-25 Classic) needed. The two Yanmar engine zincs were zinc rather than aluminum. Bought zincs from boatzincs.com
I worried a bit about mixing materials. My old boat was fully bonded but no galvanic isolator. And it was only in salt water about 50 days a year so that was a plus. I replaced all aluminum zincs once a year except for the lower engine zinc being replaced twice a season.

 

[JeffreyAC77]

Thanks for the feedback.

 

[BB marine]

I switched over to Aluminum after the second year of owning my 2016 Cutwater. The zinc did nothing in fresh water. I boated on Lake Michigan and then Florida. I replaced the zinc anode with an Aluminum and spent three months in Florida with another Cutwater owner that was using Zinc anodes. He replaced his zinc anode after 2 months. Seemed to soon but he said they were more than 50 % gone. I checked mine and it looked like there was hair going off them. I brushed them and it all fell off and the anodes were about 80%. I am using aluminum on my Mainship 34 Pilot. We have only been in salt water with it for about a month and fresh for 3 months since launching it. We left the boat sitting in Orange Beach AL. for 3 weeks at a dock. I also hit several submerged (floating below water) logs on the way down the Mississippi River and Tombigbee River. I wanted to have the Props, bottom and anodes checked and there was a diver cleaning the bottom of a boat next to me so I asked him if he would check the bottom and the hardware. He did agree to and fortunately no damage to the props and he said the Aluminum anodes looked like new with just a little hair on them. He said he did a quick wipe with a brush and they looked like new. He was impressed with how they looked and said he was going to start using them and see if they work better than the traditional zinc anodes. If you trailer your boat or have outboards I would not use Zinc anodes.

 

[RichBirk]

So, here's a related question. If you have an aluminum hard bottom inflatable dinghy with an electric start outboard, would you still attach an aluminum anode to the dinghy?

 

[Submariner]

I switched my trim tab anodes, my engine transom anode from zinc to aluminum.
I also switched the anodes on the kicker to aluminum as it's not wise to have dissimilar metal/anodes.

2 outboards, RT27-OB, all aluminum now.

After 6 months in Puget Sound they appear to be working effectively and eroding evenly.

 

[mlanger]

This is an interesting discussion for me as a newbie. I purchased my boat in Olympia and cruise for about a month out on Puget Sound. The sinks are all less than six months old and they looked fine when the boat was pulled out of the water to be shipped to Chicago.

The boat is now in freshwater (the Mississippi River) and it will probably be in fresh water for another month before I hit the gulf. Then it will be in salt water for at least half of next year. I guess my question is this: with a mix of salt and freshwater, when I pull the boat out for its next bottom inspection/painting, should I switch to aluminum? The boat will be in a mix of salt and freshwater for at least the next two years.

 

[dbsea]

This is an interesting discussion for me as a newbie. I purchased my boat in Olympia and cruise for about a month out on Puget Sound. The sinks are all less than six months old and they looked fine when the boat was pulled out of the water to be shipped to Chicago.

The boat is now in freshwater (the Mississippi River) and it will probably be in fresh water for another month before I hit the gulf. Then it will be in salt water for at least half of next year. I guess my question is this: with a mix of salt and freshwater, when I pull the boat out for its next bottom inspection/painting, should I switch to aluminum? The boat will be in a mix of salt and freshwater for at least the next two years.

Yes I would switch to aluminum! It’s the best for mixed water usage.

 

[mlanger]

Yes I would switch to aluminum! It’s the best for mixed water usage.

Thanks! I assume that when I get back to salt water only, I should change back to zinc? I do have a bunch of spare zincs that came with the boat.

 

[dbsea]

That seems to make sense! I have been told zinc is best for all salt.

 

[DocJoe]

Hello,
Newbie here, and I read an excellent article on aluminum vs zinc sacrificial anodes in BoatTest.Com recently. The article concludes that not only are aluminum better but less expensive.

Sorry, I don't have the link but easy search for BoatTest, and they also have many articles of interest.

Great being here on Tugnuts!

DocJoe

 

[mlanger]

That seems to make sense! I have been told zinc is best for all salt.

Thanks! Just a few more weeks of fresh water before I hit salt again for the winter. But when I pull it out in the spring, I’ll switch to aluminum for the mixed environment it’ll live in for the following year or two.