MERCATHODE Questions

I have a 2003 350 Mag MPI ( Horizon engine ) with the Mercathode set-up. I live in the Northeast and boat in saltwater seasonally. Every year, the mercathode unit mounted to the engines transom mount gets so fouled, all over, with barnacles that I cannot see how it can function. I take the time to carefully clean it out with a metal pick ( no chemicals ). Just about every other year I replace this thing !

Is this normal ? Should it get fouled like this ?

Is there a way to confirm that the unit is working correctly while on the hard ? ( a way to test if that serpentine wire is functioning correctly ? )

Lastly, can I paint the plastic part of this unit with antifouling that I use on my depth finder sending unit ( excluding any metal )?

If it is original it needs to be replaced anyway. so no need to test it until you install the new one.


MerCathode Reference Electrode Tester 76675A1

It's not the original - it's been replaced with new almost every (2) years. Any way to test while out of the water. I did the in-water testing a few years ago, borrowing my Mercruiser mechanic's tester. I always feel like the Mercathode set-up can give you false security.

I personally think they are useless. If you have excess corrosion, make sure all your electrical connections are clean along with your bonding wires. Make sure you have a galvanic isolator if you have shore power. Do not park your boat in a marina with a steel bulk head and do not park it next to some old neglected tub-O-S*** that is leaking voltage into the water.

Hook a bonding wire to a cleat bolt inside the hull and get a throw over anode fish with an alligator clip on the end of the wire and hook it to that cleat.

http://www.sterndrives.com/bravo3_galvanic_corrosion.html You may also want to look into adding a second Mercathode controller.

Thanks for all the responses - but I'm still curious:

is it normal for heavy barnacle growth on a working Mercathode ?
Can it be cleaned and function ?
Is there a way to confirm it is working my testing the Mercathode under the housing-mounted part while on the hard ?

Lastly, and a new question after reading the info on the link - I like the (2) Mercathode sending unit idea - but not having a dedicated charger - will (2) definitely use that much battery ? The one I have uses nothing noticeable at all.

Barnacle growth is driven by the environment, not the mercathode (working or not)...

The mercathode will work, assuming the rest of the installation is sound, as long as its electrode has good contact with the water...

The best way to tell if any cathode system is working is to use a reference electrode and measure at several points around the hull, in the water.

Two Mercathodes will use twice as much energy as one....since one doesn't give you any issues, I doubt two will...

Thank you ! I will add the 2nd Mercathode sender then.

ok...

I have a second mercathode sender that I want to either add to, or put in instead of my Blue colored mercathode. This second one is the Red version. I have read online that the Red mercathode is twice as strong as the Blue one.

Is this true ?

Would it be a problem to add, wired in series, this 'red one' to my existing 'blue one' ? Or, should I remove the blue one and just use the red one ( if it is in fact twice as strong ) ?

Just as a reminder, for application purposes, I have a (10) year old Bravo 3, stored and used for 6-7 months in saltwater. I do find that every year I have areas of paint that will chip off and expose bare aluminum - mostly on the gimbal, but a little here and there. Each year I test the daisy chained grounding for continuity and resistance. I touch the drive up, bracket and gimbal with Primocon and paint it heavily with Trilux. SS trim tabs are painted with anitfouling too to reduce SS in the water. I am very meticulous and am happy with the 'health' of my drive etc, but it is frustrating the amount of sanding, prep and painting it takes to keep it 'right'..

Thx...

http://www.boatfix.com/merc/Techbk/94/94hs7.pdf good read for protection

i have a 2003 25' crownline, bravo iii, 350 mpi, i am in the Chesapeake Bay Brackish/salt. i was in the water from May 1 to Dec. 20 last year. with very minimal growth and zero corrosion while connected to shore power next to a bulkhead.

My History:
I bought the boat used, previous owner said it had corrosion issues. i changed the entire Mercathode system, most importantly the controller. If the pucks and transome mount unit become fouled with debris or painted or plastic spacer strips become damages then the system is not working.

the Mercathode is added to change electrical properties in the water for corrosion reasons not growth.

This is what i have added and done.
changed bottom paint to Petitt Vivid Free ablative bottom paint, change Mer.