Normal or stray current?

Pat310

These were new in May. Does this seem like normal or am I dealing with stray current at the dock?  They seem to be working as the drives look fine on a quick look when it came out of water today

Liberty44140

Not normal. 

raybo3

Try checking with some of your boat neighbors and see what their zinc's looked like. 

YYZRC

Mine didn’t look nearly as bad. Same timeframe. 

Pat310

@YYZRC and @Liberty44140 if I’m not mistaken you guys are in fresh water. That might make a difference. Got a new dock neighbor half way through the season. An older sail boat 🤔 might be the problem. Will have marina check next spring

Pat310

Any of you salt water guys have an opinion?

Aqua_Aura

That doesn't seem normal for salt. Are you using zinc? I am not in saltwater. 

raybo3

I am in salt water and I usually do a "mid-season" maint. I haul and pressure wash the bottom and rezinc where needed. If I left my boat in without the mid-season it would look like that. My guess here is that your not too far from a bridge and you have a strong water current or there is a boat near you with a problem. 

YYZRC

Yes I’m in fresh water. 

TonyG13

I'm in fresh (Lake Michigan) and use magnesium anodes. I will get at least two full seasons (6 months per season) -- with a lot left over.

That does not look normal.

Sorry @Pat310 - Mixed up you and @YYZRC. Thought you were in fresh.

TonyG13

Either BoatUS or Boating magazine had an article about how to test for stray current in the water. If I can find it, I'll post the link.

Found it: https://www.boatus.com/magazine/assets/pdf/putting-corrosion-to-the-test.pdf

Cableguy Greg

How does the rest of the drive look? I would take a anode dissolving over a season versus corrosion on the drive. 

Pat310

Drive looks fine. No pitting or heavy corrosion. I am using zinc. Thanks @TonyG13 I’ll read that this weekend. @raybo3 I never thought of mid season haul. Something to think about next year. Will talk to yard boss to see what he thinks about condition of zincs. 

mattie

Pat, maybe someone installed magnesium anodes by mistake. They would be gone in a few months in salt water. I’d expect them to look like your pic if that was the case.

Pat310

@mattie I bought them and installed them myself

LaRea

Pat310 said:

@YYZRC and @Liberty44140 if I’m not mistaken you guys are in fresh water. That might make a difference. Got a new dock neighbor half way through the season. An older sail boat 🤔 might be the problem. Will have marina check next spring

If this is a sudden change after getting a new neighbor, and especially an older boat, I'd take a close look at that boat.  I had a major change when an older boat moved away from me ... suddenly my anodes started lasting two seasons.

Liberty44140

True Pat, I am freshwater 

Ian

Boatzincs.com suggest Aluminum for both, when I called to discuss this with them a few years ago the first change on my B3’s they said this was a Merc recommendation too now. So thats what I use and get 2 seasons.

TonyG13

I was always taught zinc for salt, aluminum for brackish, and magnesium for fresh.

Aqua_Aura

TonyG13 said:

I was always taught zinc for salt, aluminum for brackish, and magnesium for fresh.

Yes that is correct. 

raybo3

Lets make no mistake about it here. Zinc's are supposed to get "eaten". That's their job. I agree that those look pretty bad but they did do their job.

Aqua_Aura

Yes always better to have the sacrificial anode get corroded rather then have a sacrificial outdrive. 

Pat310

Thanks for all the input. Definitely have to do some more investigating. Happy thanksgivings