Out Drive paint and zincs

[WandaS]

I recently bottom painted. The guy who did the work told me (after he lightly sanded my out drive) that he was down to the bare
metal on the bottom of the drive unit. My question is should I paint the out drive first and then put anti-fowl primer and Petit Alumaspray next or what?

Also, some info I found suggests that there could be an electrolysis problem when the out drive is anti-fowl primed and painted.
Zincs would have to be changed quite frequently as well as other problems.

The place I am docking the boat has 30 live aboards and there is a constant need to change zincs.
Any help would be greatly appreciated.

Thanks

1998 Aquasport 215E
5.7GS w/volvo/penta sx cobra outdrive

[fitz73222]

I would follow the manufacturers recommendation for the outdrive prep. Also try to match the same manfacturer as the bottom paint for compatibility and antifouling chemistry. Make sure all of the continuity connections from the drive unit, trim rams, and gimble housing are intact and clean so there is proper grounding for the zincs to work properly. Now for the liveaboard marine environment; its pretty safe to assume there will be lots of stray current so to keep your drive unit from turning into an Alka Seltzer tablet you really should research and invest in a galvanic isolater system such as a Mercathode system or equivalent.  The system basically introduces a very low voltage blocking current that reverses the flow of electrons that attack the aluminum and even stainless steel. Well worth the investment compared to corrosion damage and replacement housings.

[GoneFission]

First go check those live-aboards.  Odds are someone (or two or three) has a reverse polarity hookup that is charging up the entire area.  All marinas prohibit reverse polarity, but it's pretty easy to check.  

My $0.02, and worth every penny...