Mercathode/Anodic questions..
 

I have a 1990 Cig with Bravo 1s. I'm not sure what year the drives are, but I'm fairly certain they are classified as "old style". When I bought the boat it had no Anodic protection on it at all. This caused a lot of corrosion on my drives last summer when I was in salt water, so I want to add the appropriate protection.

Based on what I've seen I can buy collars for the trim cylinders, Anodic bolts that come through the transom, Anodic "fin" for the drive, and some sort of Anodic "box" that I know nothing about (it's part number 821631Q1 - looks like it bolts under the Gimbal Housing). I already have the Mercathode box under the Gimbal housings.

Any recommendations on which of these I need to install?

I keep my Wellcraft on a saltwater mooring 5 months a year.

With a stainless prop, and an Alpha 1, I can burn up an entire anodic fin in about 3 months, I replace the anodic bolts every year, and ther is a big ziinc that mounts under the Bell housing on the transom, with a bunch of fins that goes 1-2 seasons.

Zincs need to be replaced when 1/2 worn away, they need to be mounted to bare metal(I use grease where the contact is), and you cant really get too much zinc. Do not paint the zincs! The active Mercathode system helps some with zinc life. Keep all the other metal painted. With 8 salt water years, my Merc. Alpha came apart for rebuild nicely, and has no noticable corrosion.

I live in Maine, so the water is cold, I have seen some real messes with warm water boats.

Dave Leonard, Zinc consumer.

If you already have a mercathode box under the gimbal it should work... It should have a very tiny fuse in the system .. make sure it is 'nt burnt out and put on as many zincs as you can but make sure the mounting bolts are completely grounded otherwise they're almost useless.Otherwise as Dave says above !.

fresh water-magnesium, salt water -aluminum. the zincs are worthless.

Like Formula 31 said, "zincs" aren't really Zinc anymore, Merc recommends Al for Saltwater, Mag for fresh..but I have had good luck running watever they had in stock at the West Marine Store..
"Canada " brand I believe..and I am not really sure of their composition.

The point is to make sure all the "conductivity washers", springs, and little connector cables are hooked up, and that the "zincs" (from now on referred to as anodes..or " sacrificial anodes" are in good shape and the whole mechanical system is well connected "bonded" is the real term I think. If you look closely you will see little SS cables wit crimped on ends for conductivity where the drive tilts. The boots have little ss metal pieces that bond the hose clamps to the drives, thru the paint, and the drive mount bolts have one bolt with no washer with a conductivity tab base plate.

Electrolysis can eat a drive!
If the anodes are working you should see serious consumption of them..they should pit and corrode to beat the band. I run a FWC heat exchanger..it is bonded to the engine with wires, and it runs "pencil zincs" in the antifreeze side of the exchanger.

I don't think fresh water causes much zinc erosion, but I have salt water in my veins so I dunno..


Happy boating, only 3 months to go.. lets see.. thats 90 days..Do I have time to pull the engine and rebuild the transom, or shall I run it another year?

Dave Leonard

Thanks for the info. Yes, I do have the mercathode box under the gimble so I'll start adding anodes.

Make sure your ground straps are in place. I believe there are 4. One each to the trim cylinders. One to the gimbal ring and one to the gimbal bell.

I've seen a lot of boats with these missing.

There is a test procedure that you well equipped Mercury marina can do. It doesn't take long.

You can do it yourself (as I did once) but I forgot the necessary readings and conditions.