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Stripes of bare aluminium appeared on outdrives

S

Samsara

New member
Hi, Recently antifouled the hull and repainted the bravo 3 outdrives, took the boat out to sea maybe 3 o 4 times since. This morning I dived to clean the drives and surprised to see several large stripes
of paint were gone, leaving only bare aluminium. I contacted immediately the marina guy who did the painting, he said he did spray primer and 2 coats of Merc phantom black enamel paint.
Did the guy use a primer that marry well with aluminium? I have no idea!
My marina is small, probably they will not allocate a freespace on the drydock for me so soon, so at the meantime will my outdrives prone to rapid corrosion ? How to protect them ?
I do not have a galvanic isolator and I heard that some boats have electrolysis problem.

Does anyone know about the cheap Yandina galvanic isolator ? worthwhile? Thks
 
Bravo`s are more prone to it.zinc replacements in good condition? Was the bottom paint kept 1 inch away from the drives?
 
shore power, battery chargers that are not marine rated, powercords or dock wiring in the water, neighbors using automotive chargers,
missing bonding wires for the drives.
 
Bonding wires are grounded to the drives, do have mercathode devices too. But not sure these devices can overcome electrolysis issues. To play safe, would it be preferable that I quickly install a galvanic isolator ?
 
Hi all,
I'm reviving this post cos my outdrives now look scary, paint seems dissolving in the saltwater. I dropped by the marina yesterday to run the boat. After the run I dived to check the outdrives and
what I discovered was not only a few stripes of paint missing but 60-70% of the drives are now bare aluminium.
My marina said that I can maybe haul my boat out in a month. (drydock currently fullhouse). I need to haul it out quickly to repaint the drives and replace a seized seacock.

My questions for you are:

1) Is there a simple way to repaint my outdrives without going thru complicated process like blasting, toxic chemical etching wash etc.... ?
I plan to repaint the drives myself, will not be able to deal with such complicated processes, neither me nor anyone else in my marina I suppose.

2) What kind of primer paint do I need to marry with aluminium, and is it ok with Merc Phantom black enamel paint as the final finishing coats?
I have taken a look at WestMarine and others, there's so many type of paints that I got my head spinning, can't even figure out what these paints really for, lol....

3) Do my drives have an immediate danger of corrosion ?
(on yes, last week I installed a galvanic isolator from safeshore, the monitoring device does not seem to indicate any stray current around my boat, good news though!)

Thanks for your help.

You might wonder why I have this problem:
I moved south for my new job by the end of 2011 and moor my boat in "my current marina" at the same period. The first haul out for antifouling in this marina was carried out on August 2012.
Mind you! a marina guy who did the antifouling was so zealous that he antifouled not only the hull, but also the 2 outdrives with the same paint which contains copper particules.
Wow!. beautiful thick black mat color below the entire waterline. I had have no choice but to put my boat back into the water and planned for a 2nd haulout in the next 6 months.
2nd haulout on march 2013, to strip out the antifouling paint from the drives, to leave a 1 1/2" gap between the drives' transom mount and the hull antifoul paint, and then primer / repaint the drives with phantom black enamel. Well, this was supposed to be done correctly (according to the marina guy) and yet my outdrives peel their paint off.
I have no idea what's going on.
 
Copied from another site so take it for what it is worth......

"""""""""""
Alodine for pre-paint surface prep
PPG DX179x waterproof wash primer
- or - Duplicolor self-etch for aerosol

dx179x is mostly used on airplanes. It is the top
primer for aluminum and has been copied by others
like dupont. It is a 2 part paint and you mix the activator
immediately beforee use. follow instructions and
do not apply coats thicker than advised.

dupliclor is an aresol. It has the best spray
nozzle and will make it easy to apply a good consistent
paint spray. It is the same thing as the other one-part
primers places like summit racing or eastwood will
sell you except in aerosol. It is not waterproof.

alodine is brand name with such market dominance that it
also serves as a gereric product type. Kind of like "aspirin".
3m, dupont, and PPG resell under their own name like
aluma-prep and it is probably available at your local
PPG or dupont distributor.

for top coat I like dupont nason, old fashioned lacquer,
or rustoleum oil based. Depends on time, $$, and
appearance. lacquer is least time, rusto is least $$,
dupont is best look.





Also look here,

http://forums.iboats.com/boat-restoration-building-hull-repair/steps-prep-aluminuim-pics-457159.html
 
Hi Kghost, I see much clearer now.
I found most of the stuffs you mentionned at aircraftspruce; alumiprep33, alodine, and duplicolor self-etch aerosol. For the final finishing coats I think I will use the original Merc phantom black enamel spray.
Before aircraftspruce I will first check with my local hardware shops for these stuffs.
Thks for the info.
 
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