Anodes

rasbury

Well, this should get the crowd stirred up, I had no idea......I need to change my anodes as they look rather spent. They do not appear to be very expensive so no excuse for running with ones ate up. I was looking on line as I expected to see this as a simple purchase decision and I see on other sites, discussions going back and forth whether to use aluminum, zinc or magnisium ????? Is nothing not simple????I am mostly in fresh water, for now, but plan to be more salt, do I really need to change the friggin anodes depending on what type of water I'm in?????

Cableguy Greg

Magnesium is for fresh water only. If I were you, I would consider the aluminum ones for brackish water, which should give you the best of both worlds.

Here is an interesting read...

Fit the correct anode material for the waters your vessel is operating in

As a general rule owners should fit the anodes suitable for the environment they most regularly berth in and the following table provides a useful guide:

Salt water  Fit  Zinc (Martyr I) or Aluminum Anodes In Brackish Water Fit  Aluminum Anodes (Martyr II) In Fresh Water  Fit  Magnesium Anode (Martyr III)

Some vessels will from time to time move between salt and fresh water, others are berthed within marinas and behind tidal barriers where the water is enclosed and likely to be brackish or even virtually fresh. Owners must be aware of the effects that this may have on their boats and fit the correct cathodic protection system to avoid corrosion.

Not all anodes are suitable for every environment, for example the surface of a zinc or aluminum anode will if left in fresh water for some time become covered with an off white crust of oxide which effectively seals the anode and stops it working even when returned to salt water. Zinc Anodes suffer a similar problem even in brackish conditions whereas Aluminum will continue to operate effectively in river estuaries and other areas of brackish water indefinitely. The consequences of this passivity of the anode are that the next most anodic item within the anode bonding system will start to sacrifice itself which could of course be very serious.

It is therefore very important to check Zinc and Aluminum anodes after any trips into fresh water and if necessary clean off or change the anodes. Should a vessel move into fresh water for more than two weeks Martyr recommends that an alternative anode system is used suitable for fresh water situations.

Magnesium Anodes on the other hand have a much higher driving voltage than zinc or aluminum making them highly suitable for use in fresh water, they will however become very active in salt water where they will probably only last a matter of months. Protected surfaces can build up a layer of off white calcareous deposit which will be difficult to remove.

Magnesium anodes are not designed for prolonged use in sea water and if you are taking your boat into a salt water location for more than seven days (Fourteen days in any one year) you should consider changing the anodes.

This is from the martyr website.

Michael T

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rasbury

Normally, my main boating is in fresh water, and I assume brackish is a comp fresh and salt. I do want to go over and run the inter coastal some, but that would be day trips or maybe an over night here and there. Once a year, I may be in salt water for a week for vacation along the coast somewhere....so, sounds like aluminum is the best over all without changing back and forth considering how long the boat actually sits in the water?

LaRea

For the pattern of use you described, you should be using magnesium.  

I use mine the same way:  it lives in fresh water, and only sees salt water for 2-3 weekend or 1-week trips each season.  I've been using magnesium for 15 years, and always had good results.  The anodes are 50% spent at the end of the season, and I replace them every spring.  

I did try aluminum one year on a previous boat.  They barely corroded at all, which means they were not doing their job.

rasbury

wow, every spring.....just one more thing to keep up with.....I'm going to rent my next boat!

LaRea

Part of my spring ritual -- paint the outdrives and replace the anodes every year.  It's not cheap, but I've seen what even 1-2 seasons of neglect can do to outdrives. 

Rent?!?  Now you're really going to stir up the nest.  Don't let RinkerYan read that post.

rasbury

the anodes I've looked at were like 60 bucks but don't recall what they were made of, aluminum I'm sure. It was a salt water boat but kept on a lift, had 98 hours on it when purchased so did not spend to much time anywhere but the lift!

Michael T

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rasbury

10-4 Mike, will change them before it goes back in the water again.....

laureniac1

Magnesium is the one just did mine on 10/16/14 on my 270. Just make sure you get the anode kit with prop anode. They make 2 anode kits from quicksilver make sure you buy the one with the prop nut

rasbury

10-4!

rasbury

I was just looking on a web site called boatzinc.com which I pulled from another post and it states if you venture into salt water even every now and then not to use mag. It does not say what you should use in lieu of but would assume brakish....

Michael T

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Mike_G

So... what do factory BIII's come with? Magnesium (I hope)?  Are they clearly marked on the anodes somewhere? -=Mike G.

Michael T

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Mike_G

I'm in Fresh water too.. St. Clair (albeit a little "fresher" than your water due to the Detroit River and all.. ), so I need Magnesium.  -=Mike G.

Michael T

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LaRea

On a boat that lives all season in salt water, magnesium (Mg) anodes will "overprotect" the boat.  Overprotection can cause problems such as blistering the paint, and reducing the effectiveness of anti-fouling paint. Google "marine anode overprotection".

For a freshwater boat that only spends occasional weekends salt water, Mg is fine.  The anodes will wear faster in salt water, but that's no big deal if you replace then every year anyway.

MT is right -- Mg anodes have special packaging with bright yellow stickers.  Can't miss 'em.

Stodge

We use magnesium anodes in LSC.  I normally have to swap them every other year.

Mike_G

Thanks Stodge!

OK, well that just means I'll probably have to swap mine this coming spring before dropping it in being that they are probably aluminum.  I highly doubt the dealer would swap them before sale for the water they are going into... I'll confirm.

Thanks again!  -=Mike G.

Britinusa

I dont think i even have any anodes on mine, ill need to check after reading this thread.

Stodge

Brit, they are normally on the rams that move your outdrive up and down, on the cavitation plate above the prop and a few other spots on the outdrive.  You should have some kind of anodes somewhere.

MarkB

Brit, if you didn't have anodes, you probably won't have much propeller left also. Current will dissolve your prop in a short time frame.

rasbury

that does not sound good Brit......make sure you still have an out drive!

Michael T

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MarkB

Brit, I just saw the other post with a picture of your drives. You definitely have to have anodes somewhere on that drive, or it wouldn't be in as decent shape as in the picture. There's no way.

rasbury

wow, I'd think my out drive was done if it looked that bad...guess they can take a licken!

raybo3

Ras what looks bad? Looks to me like its been painted but in very good shape....

Cableguy Greg

I have to agree that the drive looks to be in great shape. The anodes are doing their part.

Dream_Inn

I think Ras is used to the lift or trailer look.  I've had both ways, and those drives look great for being water kept for 7+ months.  If it is lift kept all the time, well, then I'd expect them to be nicely waxed and shiny!