Ditch MerCathode for Anode Protection?
 

I found two black plastic masses (for lack of a better term) bolted to the bottom of my gimbals where anodes can be bolted (IE under the hydraulic ram manifold). I was then told they are the cathodes for the MerCathode system and not to remove them, but I'm having other thoughts.

I have a pair (one on each engine) MerCathode (Black box) that are circa 1996. I've read multiple posts regarding the procedure for testing and how when tested they typically aren't putting out spec. current to fully protect against corrosion anyway. I've seen owners run two of them in parallel (on each engine) to gain adequate protection. I also read of testing the system one day and three days later they are dead.

For a boat not stored in the water, I would maybe have it in 72 hrs. at once if I wet slip it to stay on overnight when away from home, would it be more practical to remove the MerCathode's on the bottom of each gimbal and go with anode protection? I figure the stagnant anode protection is at least known to be "working" consistently without the worries associated with keeping the MerCathodes, which for all I know can be dead already.

Your thoughts and experiences are greatly appreciated !
Keith

If the mercathode system actually works, I'd hate to see how bad corrosion can get without it lol.

what if it's a trailer queen, and always washed rinsed, flushed
or closer to the truth, how hard is it to hook up correctly ?

Do you ever have the boat in the water, slipped, overnight, etc., WITH the shorepower attached? This is when the Mercathode is most important.

https://www.amazon.com/dp/B001QUXB2W...=I5VMKYMKM4AFX

This will help....

Agree, this is the point for the Mercathode

And Merc has testing procedure's to make sure it is working correctly as it was intended for. Also keep Anodes in check and replacing with new beforehand as well.

If you plug into shore power I would consider adding a galvanic isolator. Even though I rack store my boat I added one to mine for those long weekends I am plugged in at marinas. http://www.pkys.com/FAQ/galvanic.htm

I will, maybe a handful of times a year.

Yes I have read it, and it requires a $125 lead for my multi tester and the boat to sit in stagnant water for 8 hrs. Before testing. Then I may find I need to add another MerCathode box to the currently installed units in order to have proper protection which changes from slip to slip anyway. Or that mine are already kaput altogether being they're 20 yrs. old.

So what I'm trying to determine is, will replacing the MerCathodes with anodes provide the same protection with less headaches and at much less cost? After all new gamble anodes are ~$45/pr.

That's the next goodie on the horizon!

Anodes will assist in giving more material to sacrifice, but does not do the same job as the mercathode.

I have one of the Merc probes and its a piece of wire that has been platinum coated around a small nylon stick. You could probably get close if you silver plated a 18AWG wire, but not exact due to differences in properties

Thanks for the info.

The 2nd paragraph is what I'm trying to get away from if possible. "Known Knowns" seem to lacking with MerCathode testing and usage. Other than being unreliable and a PITA to test.:D

These can be helpful. If you're on shorepower or in a marina overnight. Extra protection doesn't hurt.

https://www.google.com/shopping/prod...owpxoCXPvw_wcB

I don't fish.........hahaha good idea for extra peace of mind.

Never gave that a thought.

It's real easy to test, after sitting for 24 hours and the boat plugged in connect the probe to the positive connection of a digital multimeter. The other connection goes to boats battery ground. Set meter scale to 2000mV and drop probe in the water within 6 inches of the rear of the drive. There are two types of anodes and yours is listed at the bottom set

a. MODELS WITH ELECTRODE MOUNTED ON BOAT TRANSOM
Fresh Water Areas Salt, Polluted or Mineral Laden Water Areas
Quicksilver VOA Meter 7.5 - 10.5 millivolts 8.8 - 10.5 millivolts
Digital Meter 750 - 1050 millivolts 880 - 1050 millivolts

b. MODELS WITH ELECTRODE MOUNTED ON BOTTOM OF TRANSOM ASSEMBLY
Fresh Water Areas Salt, Polluted or Mineral Laden Water Areas
Quicksilver VOA Meter 6.2 - 11.8 millivolts 7.5 - 11.8 millivolts
Digital Meter 620 - 1180 millivolts 750 - 1180 millivolts

Start on page 7A-20.
http://www.boatfix.com/merc/servmanl/14/14a7.pdf

BTW if your not seeing any paint missing off the drive after being in the water my guess is your fine

I don't either but plenty of friends use them on our overnight runs to marinas just for peace of mind

Thanks that's the shorthand version of the manual and much easier to understand. I'll get the boat in the water and see where the MerCathodes stand test-wise before ditching them. Found out a buddy has the Merc. probe that I can borrow so that makes the decision easier at the moment.

I ditched my mercathode system. I do a few overnights a year, and slip it for one full week every summer. No issues at all. I boat in freshwater only.

How fast the anodes are eaten up is something to look into as well. Once 50 % gone they need to be replace asap or sooner.

Did you ever test the MerCathode? Did you simply affix anodes in their place? Thanks for your perspective.

10-4 on that, thanks for reiterating what I've read elsewhere. When I bought the boat the hydraulic ram anodes were dark gray and down to the mounting bolts. I immediately installed 4 new units (2 outdrives).

Guys remember:
Zinc for salt water
Aluminum for salt or fresh water
Magnesium for fresh water

I have a few boats that I service that are low 1990's that I replace the aluminum anodes every few years that the outdrives and etc still look real good. Yes, original outdrives. These sit at docks in fresh water by themselves from early June thru late September. No shore power.

Some other boats in area where owner refuses to have anodes replaced (silly isn't it) the outdrives look like total schit. Same people will sand down and redo paint on outdrives every few years. I show them the older boats outdrives I referenced above and they still just shrug there shoulders.

Crazy !

Most people are just their own enemies.