How long should anodes last?

[KnotConnected]

Quick Question.

If you haven't been following my plethora of "how to fix X" and other problems i've been having, corosion has been a big troublemaker for me this spring.

My outdrive has 4 anodes, the two on the trim cylinders, the flat round skeg anode, and the U shaped anode forward of the outdrive. Boat went in the water ~may 15th, and I'm already starting to see a little bit of corosion on the surface of the trim pump anodes (the only two I can clearly see while the boats in the water). They're no where near needing to be replaced yet, but they are clearly showing a bit of corrosion on the surface. Is this normal, or could I still have an issue thats causing them to waste a way a bit?

At this rate I'm probably looking at replacing the set of 4 every year.

(Fresh water, 1994 Larson Cabrio 280, single 7.4L Bravo III, hooked up to shore power 24/7)

 

[rbh]

Re: How long should anodes last?

If your going through anodes that fast in fresh water your shore power circuit is having a grounding issue I think.

 

[Don S]

Re: How long should anodes last?

That is what they are supposed to do. I know in salt water the anodes get replaced yearly on boats that stay in the water.

It could be the dock power, or it could be other boats around you causing excessive corrosion.

 

[Home Cookin']

Re: How long should anodes last?

my anodes on the trim tabs go pretty quick (annually), but (a) they are underwater on an electrified device and (b) they are underwater around antifouling paint. They are also fairly small

The skeg annode stays out of the water and lasts; the U annode shows signs but it's thicker.

I turn off my batteries when moored to eliminate power trickle.

Do you really need to be hooked to shore power constantly? Less is better. Why not unplug?

If you are in a marina not much you can do about others but I've heard some horror stories about big power leaks at or near marinas.

 

[tpenfield]

Re: How long should anodes last?

Be happy about your anodes starting to show signs of depletion . . . that means they are working.

Make sure that your Mercathode is working, as well. Keep an eye on the anodes for excessive depletion.

 

[Thalasso]

Re: How long should anodes last?

The reason for anode depletion is caused from different issues. You should be glad to see them depleting to some extent. That means they are doing what they are designed to do.You should be getting at least a season out of them in freshwater. If not there is a problem. You should have a galvanic idolater that breaks the ground from the shore power (so to speak). Yearly replacement cost is cheap considered the alternative.

 

[KnotConnected]

Re: How long should anodes last?

Yeah, I was thinking the same, regarding the deterioration meaning they're working. I'm not sure if i have a galvonic isolator OEM. The power is hard to trace up from where the inlit is.

as for the Mercathode, I've verified power with the voltmeter on the + and - leads on the controler, and the other two leads look connected. Also, the electrode is present under the outdrive. so, it should be working? I couldn't find the controler until after the boat went in the water, so I can't currently test continuity until its pulled back out, unless someone has a tip for this?

I generally leave my batteries off, but like to keep the shore power connected so the battery charger /tender can work and the fridge is keeping cool while I'm away.

 

[TilliamWe]

Re: How long should anodes last?

I generally leave my batteries off, but like to keep the shore power connected so the battery charger /tender can work and the fridge is keeping cool while I'm away.

Okay, the batteries off *could* be a problem. The way the switch was wired in my boat, turning the batteries off turned the Mercathode off. You MUST know if your is actually functioning. There is a link on here somewhere to test it. It's not just whether the wires are connected or not.

Also, you NEED a galvanic isolator. Bravo 3s are very prone to corrosion. And with it being hooked to shorepower all the time, your is at EXTREME risk. Don't let this happen to you:





That's two - 6 month seasons in freshwater (Illinois River), no shorepower, with the Mercathode turned off. I started leaving my batteries on, switched to "Freshwater Only" anodes (much more expensive) and the corrosion never worsened in 6 more seasons.

 

[UncleWillie]

Re: How long should anodes last?

...I'm already starting to see a little bit of corrosion on the surface of the trim pump anodes (the only two I can clearly see while the boats in the water). They're no where near needing to be replaced yet, but they are clearly showing a bit of corrosion on the surface. Is this normal, or could I still have an issue thats causing them to waste a way a bit?

It depends on what "a little bit of corrosion" Means. ??? A picture would help.
While Flakey Powder is normal. The "New Look" will go away almost instantly.

White Flakey Powder is normal.
If they look like a 10 Year old Aluminum Engine Block, That is normal.
If they already look like squirrels have been chewing on them, That is excessive.

 

[KnotConnected]

Re: How long should anodes last?

OH god, yeah. I just dropped $3500 on a new lower because that was exactly what happened :-\ With the batteries OFF, the voltage to the mercathode is showing 12v, so we should be good?

Tilliam: Did you have anodes when that happened? as I've said i had the *exact* same problem when I bought the boat, but I'm not sure if i have an issue, or if the previous owner was just a jackass (the anodes were pretty shot when I got the thing). I am using the fresh-water anodes, and my biggest hope is that I can keep an eye on them twice a week, and that if this DOES start to happen, the anodes will go before the lower-unit does, and at a minimum I can pull the boat before i have a bigger problem.

Also, with regards to the galvonic isolator: Duley noted. I'll try to get one ordered and installed this weekend.

 

[noclutch]

Re: How long should anodes last?

Would it be prudent to switch out anodes on my trailered boat when going from my usual (80% of the time) fresh to slightly brackish water before a few days and nights in salt to very brackish? (though not hooked to AC at night)
FWIW I have the OEM aluminum anodes on it now, and have a fair amount of bubbling and peeling paint on my VP drive at less than 200 hours in the water and never hooked to shore power. Would changing from an aluminum to SS prop increase the corrosion? ( that dissimilar metals thing)

 

[Thalasso]

Re: How long should anodes last?

OH god, yeah. I just dropped $3500 on a new lower because that was exactly what happened :-\ With the batteries OFF, the voltage to the mercathode is showing 12v, so we should be good?

Tilliam: Did you have anodes when that happened? as I've said i had the *exact* same problem when I bought the boat, but I'm not sure if i have an issue, or if the previous owner was just a jackass (the anodes were pretty shot when I got the thing). I am using the fresh-water anodes, and my biggest hope is that I can keep an eye on them twice a week, and that if this DOES start to happen, the anodes will go before the lower-unit does, and at a minimum I can pull the boat before i have a bigger problem.

Also, with regards to the galvonic isolator: Duley noted. I'll try to get one ordered and installed this weekend.

Before you order one remove the breaker panel and see if it's not in there. That's where they usually are. It will only have a green ground wire in and out. I can walk you through how to get more protection from your mercathode. You have to be carefull because you can overproteck your drives and end up with the same problem

 

[Thalasso]

Re: How long should anodes last?

Would it be prudent to switch out anodes on my trailered boat when going from my usual (80% of the time) fresh to slightly brackish water before a few days and nights in salt to very brackish? (though not hooked to AC at night)
FWIW I have the OEM aluminum anodes on it now, and have a fair amount of bubbling and peeling paint on my VP drive at less than 200 hours in the water and never hooked to shore power. Would changing from an aluminum to SS prop increase the corrosion? ( that dissimilar metals thing)

Is the 80% of the time mean it's in the water constantly.
Not hooked to shore power and kept in the water for a couple of days at a time i wouldn't worry about it.
Not necessarily but changing from aluminum prop to stainless increase your chances. I have DPS-A's and there in fresh water all summer and hooked to shore power and luckily i guess i don't have any problem other then some paint touch up.
You trailer your boat and you have this?( fair amount of bubbling and peeling paint). This sign is your drive is over protected.

 

[noclutch]

Re: How long should anodes last?

Thanks Thaiasso- no 80% of it's hours are in fresh to brackish, 20% in salt to brackish ( St Johns river and east Florida ICW respectively) But less than 200hrs total in the water, the rest sitting in the garage, unfortunately.
Yea I figured the prop may be part of the problem as the junction between the drive bearing carrier and gear housing is the most affected.
So aluminum anodes for my situation may make it over protected? Might I be better off taking the aluminum ones off when on the river and only putting them on when in salt? ( the river is fairly acidic water I'd believe due to the tanin staining from cypress tress FWIW- it turned my GFs sterling silver anklet brown last weekend LOL)

 

[Thalasso]

Re: How long should anodes last?

Thanks Thaiasso- no 80% of it's hours are in fresh to brackish, 20% in salt to brackish ( St Johns river and east Florida ICW respectively) But less than 200hrs total in the water, the rest sitting in the garage, unfortunately.
Yea I figured the prop may be part of the problem as the junction between the drive bearing carrier and gear housing is the most affected.
So aluminum anodes for my situation may make it over protected? Might I be better off taking the aluminum ones off when on the river and only putting them on when in salt? ( the river is fairly acidic water I'd believe due to the tanin staining from cypress tress FWIW- it turned my GFs sterling silver anklet brown last weekend LOL)

Aluminum anodes is for brackish/salt. .Aluminum anodes should be ok in fresh also for the amount of time in either type of water The mercathode should be helping.I think Merc is now coming standard with aluminum from the factory when it used to be zinc. I see no need to change them.Just keep the batteries up because the mercathode works off of them even if your not plugged in to shore power.

 

[KnotConnected]

Re: How long should anodes last?

Before you order one remove the breaker panel and see if it's not in there. That's where they usually are. It will only have a green ground wire in and out. I can walk you through how to get more protection from your mercathode. You have to be carefull because you can overproteck your drives and end up with the same problem

Thalasso, you're a saint. I'll pull the breaker pannel probably tomorrow night and check. I asume if I cut power at the shore power source breakers on the dock, then turn off the batteries and turn both 12v and 120v master breakers to "OFF" I should be safe?

 

[noclutch]

Re: How long should anodes last?

No mercathode on my Volvo Penta. Sounds like a great idea though!

 

[Thalasso]

Re: How long should anodes last?

No mercathode on my Volvo Penta though. Sounds like a great idea though!

Volvo doesn't use the Mercathode system. Only Merc. The OP has a Merc Bravo111

 

[Thalasso]

Re: How long should anodes last?

Thalasso, you're a saint. I'll pull the breaker pannel probably tomorrow night and check. I asume if I cut power at the shore power source breakers on the dock, then turn off the batteries and turn both 12v and 120v master breakers to "OFF" I should be safe?

Just make sure the shore-power is disconnected from boat.


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