Zincs on aluminum boats

I haven't been paying too much attention to zincs since I bought my boat. In doing some reading, I think I should change my ways. I have a zinc on my outboard, but none on the aluminum hull. My engine mounts to the transom over a rubber vibration-reducing mat. Where should I mount any anodes on the boat? I'm a little tentative about drilling holes in the hull. Should I be concerned about anodes slowing the boat down at high speeds? Thanks!

Unless your boating in saltwater,why would you need more anodes? If you are boating in saltwater,then I guess you might.I have two on both my main o/b and my kicker.I usually take them off about once a year. I will clean them up with a little emery cloth. If you have a problem with corrosion,it should affect the motor's anodes first. I have NO experience with boating in saltwater.Maybe someone will chime in.

Okay..................... you guys have lost me. What do these things do? What are they intended to do? Will it help me catch as many fish as you do Timlaugh hyst

Propnut69 said:

Unless your boating in saltwater,why would you need more anodes? If you are boating in saltwater,then I guess you might.I have two on both my main o/b and my kicker.I usually take them off about once a year. I will clean them up with a little emery cloth. If you have a problem with corrosion,it should affect the motor's anodes first. I have NO experience with boating in saltwater.Maybe someone will chime in.

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I occasionally run my boat in saltwater. When I bought it used, it had some corrosion on the side chines. It looks a little like termites got to it. I was thinking that another anode or two on the hull might prevent more damage.
My motor anode is fine...I'll try cleaning it up this year and see what difference it makes.

Mark, this is my understanding on what anodes are ,and what they do.Any time that two or more dissimilar metals (aluminum hulled boat,cast iron out drives,stainless steel down rigger cable,etc)are passed through water,within the same field.Electrolysis will occur. This causes the boat to become "hot". We have had discussions before about,the affects of a hot boat on fish. The sacrificial anodes placed on the lower unit will draw,this stray current to them. Therefore the anodes will help to protect the hull,as they corrode before the hull will . I don't know if fiber glassed hulls need anodes or not,but I know most of,if not all aluminum boat makers insist on anodes.

One thing I did learn about anodes ,is that there are three different types. Zinc for saltwater only.Aluminum for saltwater or brackish water. Magnesium for fresh water only.

As for helping you catch fish like me,well that's not possible.laugh hyst.. you just need more azz time on the water.

Full_Monte said:

I occasionally run my boat in saltwater. When I bought it used, it had some corrosion on the side chines. It looks a little like termites got to it. I was thinking that another anode or two on the hull might prevent more damage.
My motor anode is fine...I'll try cleaning it up this year and see what difference it makes.

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That would make perfect sense as to why you would need some more anodes. As where to place them,i would have no idea . Maybe the boat manufacture can help.

Ok, So where do you find these annodes at for me. I like you Tim have an outboard, Alluminum hull, How pricey are they.

You are he fish God!worthy12

And I think your on the verge of breaking out to be a Rockstarlaugh hyst

google protroll black box techniques for more info on this...

Propnut69 said:

One thing I did learn about anodes ,is that there are three different types. Zinc for saltwater only.Aluminum for saltwater or brackish water. Magnesium for fresh water only.

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That's interesting. I didn't know there were different materials used for sacrificial anodes. Magnesium should work well for an anode as it is even more "sacrificial" than zinc. I don't understand why you would use an aluminum anode on an aluminum boat. Depending on the different types of aluminum in the boat and the anode, wouldn't it be possible that the boat would corrode instead of the sacrificial anode?

this is a good site that explains the effects of corrosion and anodes.
http://www.clubmarine.com.au/internet/clubmarine.nsf/docs/MG19-5+Technical#top

"That's interesting. I didn't know there were different materials used for sacrificial anodes. Magnesium should work well for an anode as it is even more "sacrificial" than zinc. I don't understand why you would use an aluminum anode on an aluminum boat. Depending on the different types of aluminum in the boat and the anode, wouldn't it be possible that the boat would corrode instead of the sacrificial anode?"

I can't find the site where I read that it.It might have something to do with the nobility of the metals. With both saltwater and brackish water having more electrolytes,they will be more corrosive then freshwater.Magnesium might be more "sacrificial" then zinc in fresh water. Where zinc might be more sacrificial in saltwater. All three of these metals have poor nobility rating,that why they make such good material for anodes

"Ok, So where do you find these anodes at for me. I like you Tim have an outboard, Aluminum hull, How pricey are they". Mark I have no idea if our boats have anodes with in the hulls or not.I have never seen one on my boat,if it does have one. I was told by a "boat guy" that newer aluminum hulls don't need anodes,as the hulls are painted with a non corrosive bottom paint. I don't how true that is or not,but after ten years my hull still looks in great shape.

You are he fish God! Not me my friend,just one of the disciples.

And I think your on the verge of breaking out to be a Rockstar WoW!!!! that means I will have groupies.laugh hyst

Propnut69 said:

And I think your on the verge of breaking out to be a Rockstar WoW!!!! that means I will have groupies.laugh hyst

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and mark will be one of them. I hope you can still walk threw the door when your head gets big.laugh hyst

Tim, can Jason be the president of your fan club?

Propnuts...thanks for the link to the article. I don't think an aluminum anode on an aluminum boat is a good idea because it wouldn't be clear whether the anode would corrode or the aluminum boat would.

Does anyone have experience mounting these things on an aluminum boat? Most of my corrosion is in the front third of the boat. Does that mean I should put my zincs up there? Thanks!

I was looking at another fish site when the topic of,electrolysis came up. I found this info ,it came straight from the Scotty downrigger hand book. Thought it might help someone.
level to suit your target fish.
Fish Recommended
Species Voltage
Chinook (King) Salmon .600 volts
Coho (Silver) Salmon .650 volts
Sockeye Salmon .750 volts
Kokanee Salmon .650 volts
Halibut .450 volts
Laketrout (Mackinaw) .650 volts
Rainbow & Brown Trout .650 volts
Cutthroat Trout .650 volts
Black Bass .750 volts
Shark .400 volts
Striped Bass .650 volts
Sturgeon .500 volts
Catfish .500 volts

My boat (Fiberform) was parked for 9 years and when I was done restoring it I was having difficulty getting fish and a friend asked if I had checked and cleaned the anodes. Well after I had put a wire wheel to them the catch rate went up the next trip (14 kokes to the net) so its my belief that the current in the water can make a difference in the effect it has on fish. I have a Cannon down rigger with Pos ion current (Fixed at .500) so with the “bad” current from the dirty anodes it was not attracting the fish as it should.




This is some info I copied from my west marine catalog

What you are dealing with is galvanic corrosion (sometimes erroneously called electrolysis) it happens when two different metals are touching each other or are electrically connected by a conductor and are immersed in an electrolyte (an electrically conductive fluid like salt water) an electro-chemical reaction can occur. One of the metals (the least noble metal called an anode) will corrode faster than it normally would and the other (the most noble metal or the cathode) will dissolve more slowly

Zinc or aluminum for salt water
Magnesium for fresh water
Aluminum for brackish water

The prices are from $5 to $50 for anodes zinc or mag.

I know that the big aluminum boats (North river,Duckworth,Rouge) have them so I would think they are important on all boats .

GVF,

Where do you put your anodes on your aluminum boat? Do you drill holes through it to attach them?

Full Monte the boat I am referring to is a fiberglass boat and the anode for the hull is mounted by screws into the transom.

I looked up some more info about Zincs some things that I did not know.

There is an unfortunate misconception that a sacrificial anode can be mounted anywhere, even hung over the side on a string, and it will still perform its appointed duty. That is dead wrong!

For a zinc anode to provide any protection, it must be in electrical contact with the metal being protected. The conductivity of the water is not adequate. We need low-resistance, metal-to-metal contact-either by mounting the zinc directly to the metal being protected or by con- necting the two with a wire. A hanging anode can provide protection if it is connected by a wire to the metal being protected.

Where the zinc is mounted directly to the protected metal-bolted to the side of a metal rudder, for example-it is essential to make sure the surface under the zinc is bare and bright before the anode is installed. This is to ensure good electrical contact.

This info is also a good read on galvanic corrosion
http://findarticles.com/p/articles/mi_m0BQK/is_1_11/ai_n16019438

GVF asked me to add some photos of the Anodes that are on my boat so everyone can get an idea of what to look for.

These first two images are of the anodes on a Yamaha T8




There are two Anodes on the Yamaha F150 one tab just above and aft of the prop and one under the tilt trim unit.


And finally one of the two anodes as mounted to the hull.