Anode replacement for trailered boat

[elf62]

I recently read an article that recommended that anodes be replaced every year. I have also seen some threads that say anodes only need replacement if they are visibly reduced in size.

I have a bowrider (Four Winns H200) with a Volvo Penta 4.3 L GXi with SX drive that I trailer to a freshwater lake and run about 16 hrs per year. I also trailer to a freshwater river about 20 hrs per year. However, I run it in brackish water about another 24 hours per year.

My question is whether the anode needs to replaced even if it is not visibly reduced in size. Also, if it does not need replacing, is there other maintenance I should be performing?

Last, since the previous owner used the boat exclusively on a freshwater lake, I don't know if the anode is magnesium or aluminum. From what I have read, I should be using an alumimum anode since I operate in freshwater and brackish water. Is there any way to find out what the anode is made of?

 

[Bondo]

Re: Anode replacement for trailered boat

Ayuh,.... Welcome Aboard,.... You've been readin' Too much,.... yer drive ain't Corrodin' off the transom is it,..??

If yer anodes look, Ok,... Don't worry 'bout 'em....

Those articles are written to Sell anodes...

 

[airshot]

Re: Anode replacement for trailered boat

I have always replaced when visibly reduced in size or appears to be ready to fall off. In salt water they will corrode much faster, but I only boat in fresh water so I have only replaced a couple in 40 plus years on the water. My guess is those who recommend replacing every year are probably the guys who sell them.

Airshot

 

[Thalasso]

Re: Anode replacement for trailered boat

Trailered boat? Don't worry about them.You only need to watch them if you keep your boat in the water.

 

[Thalasso]

Re: Anode replacement for trailered boat

I have always replaced when visibly reduced in size or appears to be ready to fall off. In salt water they will corrode much faster, but I only boat in fresh water so I have only replaced a couple in 40 plus years on the water. My guess is those who recommend replacing every year are probably the guys who sell them.

Airshot

Mine get replaced every year. I am tied up with shore power and around a lot of other boats

 

[airshot]

Re: Anode replacement for trailered boat

Mine get replaced every year. I am tied up with shore power and around a lot of other boats

You have a very good reason to do so, his and mine are trailered so why waste the money.

Airshot

 

[crabby captain john]

Re: Anode replacement for trailered boat

My boat is dry stack stored inside and replaced both anodes this year-- year 6

 

[H20Rat]

Re: Anode replacement for trailered boat

In 20 years of freshwater boat ownership, I've replaced exactly ONE set of anodes! OP, at your usage rates, I'd schedule a replacement somewhere around the year 2030.

 

[Ned L]

Re: Anode replacement for trailered boat

"I am tied up with shore power and around a lot of other boats " Uhm, ......... If you have a problem here, this is due to "stray current corrosion" and has really nothing to do with "galvanic corrosion". Anodes ('zincs' in salt water) are to protect against "galvanic corrosion" and do nothing to protect from "stray current corrosion". Two different problems with two different solutions.

 

[BobGinCO]

Re: Anode replacement for trailered boat

freshwater lake and run about 16 hrs per year.
freshwater river about 20 hrs per year
brackish water about another 24 hours per year.

You're not spending enough time on your boat. Get out more.

 

[Outsider]

Re: Anode replacement for trailered boat

Anodes ('zincs' in salt water) are to protect against "galvanic corrosion" and do nothing to protect from "stray current corrosion".

So, what corrodes in the case of 'stray current corrosion'? My experience is the zincs will be rapidly consumed, followed by the next noble metal connected in the 'circuit, usually the outdrive/lower unit (can't tell you about inboards, never owned one) ... BoatUS - BoatTech - Types of Marine Corrosion

 

[elf62]

Re: Anode replacement for trailered boat

Actually get closer to 70 hours but get your point, I wish it was more. Then again, that is engine run time. The boat is probably in the water closer to 80 90 hours but I do wish it was more. Maybe when i retire and move further south!

Thanks to all for the advice. Can anyone weigh in on how to tell whether my anode is magnesium or aluminum? It may not matter since the boat is not in the water much but it would be nice to know...

 

[Ned L]

Re: Anode replacement for trailered boat

Outsider-- I believe if you have a stray current corrosion problem it will affect all the metals in contact with the water. Zincs/anodes do not really help you. They are affected the most only because they are in 100% contact with the water. Your lower unit is painted, which if the paint is intact will provide protection because it electrically insulates from the water.

 

[Outsider]

Re: Anode replacement for trailered boat

Would not the same principle be involved as galvanic corrosion even though the lower unit is only a 'pass through' medium? It's loss of electrons into the water in both cases, why would 'stray' current not take the path of least resistance and exit (eating) the anodes, too, at a rate commensurate with strength of current?