Hi, I have a 242 Formula with alpha out drive. I just got it out for the season from Cape Cod. I used it for a month in the saltwater, before it was always a freshwater boat. Before I put it in the salt water I put the zinks on, one each tab, above the prop and two on the nuts of the out drive. After one month, they are basically gone. I am starting to see a little bit of pitting on the out drive, nothing serious, but I don't want any more to happen.
I was wondering if anyone knew why the zinks are gone after such a short time. Any suggestions would be great. I am going to replace them again in the spring but want to make sure they last more than a month. Please leave some suggestions.

Thank you

Here is the specs.
Formula 242, Alpha out drive 350 motor.
SS prop
Salt water zinks were put on it
kept on a dock that had galvanized poles.
Driving 3 Times a week.

i would say if their almost gone that they are doing thair job,do you have the boat's shore power pluged in? or if anybody next to you has shore power pluged in? if so they or your boats power going to the boat may have a bad ground going to the boat..

some more info..http://www.defender.com/html/zincs_info.html

Welcome to the world of salt water boating. If all you've ever done is fresh water boating, you'll find out that you've been very spoiled. Salt water just eats things up. As for your zinc anodes, they were doing exactly what they were designed to do. At least you have an Alpha drive. You ought to see what heppens to Bravo 3 drives due to the large concentrations of dissimilar metals. If you have nothing to do on a Saturday night, you can sit and watch your drive dissolve.

Thank you for the response, I have actually always been a salt water boater, but this boat has always been a freshwater boat (i bought it in NH and 100% freshwater). I know about the zinks and how salt water corrodes everything. I know the zinks are doing their job, but im afraid that they are getting warn to quickly. Friends of mine have a 223 with a I/O and his zinks don't get eaten up as bad.
I dont have any shore power nor does anyone on the dock.
I was wondering if it could be a mercathode or bad ground. Im not to sure how those work and want to learn more about it. I guess check all the grounds? Any more suggestions would be awesome, but thank you for this information.

I tend to agree that one month is too soon to need zincs. Check for stray current at your dock. A bad battery charger on your boat will cause what you are experiencing. Is your boat plugged-in all the time?

You may need to add cathode protection to your boat. It could be the dock, other boats or bad grounds on your boat.



Darrell.

PS check out boatcorrosion.com. They have cathode protection systems for any size boat.

I've had good luck using the zinc fish.
It is a BIG zinc shaped like a fish, it is attached to a heavy guage wire with a clamp to attach it to the engine block.
West marine should have it.

X2 on this one. In fact more often than not, it's somebody else near you that is causing your problems. Your marina should be able to test for this condition for you. Boat/US actually had a really good article in their internal magazine on this condition last summer.

As you probably already know, once your anodes are gone, the only thing left to corrode is a much more expensive bit.

Use Magnesium anodes for fresh water applications. For salt or brackish water use Zinc anodes.
The Magnesium anodes will be eaten up fast in salt water.

Ya there is not power on the dock. Its a neighbors dock with 2 boats on it (mine and his) I guess i have to check the grounds and make sure all the wires are good.