Chris288

I boat on the hudson river, it's for the most part fresh water where we boat and I believe I have alum. anodes. The boat probably sat in the water for a total of 2 months on and off, in 2 weeks out 1 for the entire season, my anodes are in perfect shape, shouldn' they have atleast decayed somewhat ?? some say the water is brackish, maybe at hight tide it could be but I still believe its for the most part fresh.. The paint on the drive is fine, but a tiny bit pitted around the top cap.. This has me concerned which are the correct anodes ??

CigDaze

In freshwater, your best bets are either aluminum or magnesium.
In Salt, zinc is best.

Maybe there's more salt in your area than you think, or perhaps there is some stray current from a nearby boat.

fund razor

Maybe you didn't have a lot of electrolysis?

If you had the "wrong" anode, the drive would become sacrificial, rather than the anode.

Plus, maybe you aren't mixing metals much.
Maybe you aren't using shore power much, or docking next to a steel hull (that screwed me one year, pulled out an alpha that was half gone!)

Somebody correct me if I'm wrong, but these days they are using Magnesium for fresh, yes?

fund razor

Maybe try a zinc? See how brackish it really is?

BROWNIE

If you are plugged into a 3 wire shore power cord on a dock with other boats, nothing will help you. You are bonded to the other guys on the dock, and are protecting their bronze props with your aluminum drive. If that is the case, you are doing all that you can do.

Chris288

I dont have shore power, and when I asked sunsation about different anodes, they said whatever came with the drives,, them being in michigan I assume and they look to be alum. for fresh water. My wife used to keep her boat a lot farther south, where it truely was brackish / saltier, her anodes usually lasted 2 seasons of being in 24/7 for 6 months and she used zinc. 26 sonic from the board went through 2 lowers in the marina up the river from me, but turned out his mercathode wasn't hooked up correctly, so I understand that.. just surprised the anodes aren't atleast a little eroded...

fund razor

Especially since nothing else is.

I had good luck this year, hardly any pitting or anything at all.
But I have OMCs. Resistance to electrolysis is one of their few strong points.

Reed Jensen

If the water is fresh... there isn't the "medium" for the electrolysis... you will find the salt acts like an electrolyte.. much like the acid in a battery. So... the "least noble" metal protects the most... where salt water is... Zinc works well.. . but you have to clean them off often... in fresh water use magnesium... they offer the most protection in a water that is absent of electrolytes... but... if you put the magnesium in salt water... they won't last long at all... If you are next to people with a metal hull with shore power and in salt water.... It won't matter what anode you have.... your alloy parts in the water are going to suffer. Some engines have a provision for a pencil anode that goes where the drain plug was. If you are mostly in fresh water... don't let it worry you too much.

Reed Jensen

If you are in salt water at all... there are some crazy things that happen... if you have any steel touching alloy directly... there will be pitting underneath... for example... The trim indicator mounts on the tilt rams... I found wrapping them with electrical tape to isolate the metals worked well... but I had zinc anodes on EVERYTHING alloy on the stern. I had them on the trim tabs, gimbal housings, tilt rams, steering rams, outdrives, trim tab mounts, you name it... Even after washing and never leaving the boat in salt water for more than a few hours at a time.... the anodes were incredibly pitted at the end of each year. The other thing to remember is the anodes have to be mounted on a clean bare surface.. they must contact the metal they are protecting.. and periodically they must be removed and the mating surfaces cleaned for a good "connection"...

Chris288

Thanks Reedy...