Slowing corrosion on VP drive?

[noclutch]

My SX-A out drive has some areas of bubbling and peeling paint despite being out of the water almost all of the time, used mostly in fresh water, and washed well after every (rare) salt outing including engine flush run through on the muffs or a quick turn around to fresh water running. The sacrificial anodes actually look too good - ie not a whole lot of material is missing.

Will it do any good to spray or brush these corroding areas (after scraping off the real loose paint) with any particular type or brand of penetrating or protective oil prior to a salty weekends excursion?? I know that wire brushing, sanding , priming and repainting is the best option, but would it be worth my time to apply anything quickly as I have less than 24 hours before I put in the brine of St Augustine?

Thanks all

 

[Thalasso]

Re: Slowing corrosion on VP drive?

Bubbling paint is a indication of over protection. Wire brushing is a no no unless the wire is stainless or brass.
If your putting in brine water for awhile, change the anodes to aluminum.

 

[noclutch]

Re: Slowing corrosion on VP drive?

Thanks Thalasso- Over protection? Please explain if you will. Since it looked bad I figured it was :/

There are two anodes- one on the drive between the hydraulic rams, and one on the underside of the transom plate. Might I change one to aluminum and leave one (magnesium I'm guessing)?

edit: is there anything relatively eco-friendly to consider applying to the "lesions"... don't want to run afoul of mother nature ( whilst I burn gasoline at 7+ gph - could be a lot worse though LOL)

 

[Thalasso]

Re: Slowing corrosion on VP drive?

Was the boat a used one that you bought? The only cause for the most part (corrosion) is if it was hooked to shore power for long periods.Or if boat has a bonding problem. If stored on a trailer you shouldn't have any corrosion

Corrosion Quiz: Question 1 - BoatZincs.com
Corrosion Quiz: Question 1
To get the reading numbers listed in this site you need a Silver Chloride tester

In freshwater, zinc can form a coating.
This quickly insulates the anode and stops it from working.You may think your zinc anodes are lasting a long time when in fact they have simply stopped working -(stopped protecting)!

You should wipe it down with acetone and sand the drive with an aluminum oxide sandpaper.Wipe again with acetone. Coat it with Zinc Chromate and repaint

Edit:
If stored on a trailer and never hooked to shore power while in the water there actually isn't any need for anodes

 

[noclutch]

Re: Slowing corrosion on VP drive?

It was new in '07, never hooked to shore power, on a trailer 350 days a year (unfortunately) tough it does spend a half dozen overnights in fresh or salt water each year. again not hooked up to power. Thanks for the link....I never thought about that stuff!

So is that why there is a wire coming off of the drain plug housing on the bilge side?? Could it be that that wire is not properly grounded? To get a reading of the bonding system though I need a silver chloride tester, but would an automotive style voltmeter be of any use? In that link you provided they mentioned stray voltage....ugh, I know that can be a tough on to track down.

Should I "rough up" the anodes surface with aluminum oxide sandpaper to lessen any build up?

Way back in my memory banks I think I remember the boat dealer saying that I could remove the anodes if in fresh water only?- confirming your statement about not needing them in the first place. Does that mean that their presence may be the source of my problems as I'm in fresh 95% of the time?? Could it be they are zinc, thus "overprotecting"? I guess If I take one off and it seems heavier than aluminum or magnesium I can assume it being zinc, and should source some aluminum, or magnesium ones?? Did I read correctly on this forum elsewhere that mg is for fresh, alum for brackish and zinc for salt?

Thanks!

 

[Thalasso]

Re: Slowing corrosion on VP drive?

Boats that are trailered or kept on boat lifts or boat hotels are not subject to current corrosion. But those left in the water for a long period of time will be subject to DC ground current and to a lesser degree AC ground current.One or two nights won't be an issue.The silver chloride tester will tell you how well your system is protected only. All metal parts should be bonded to ground.Anodes at this point isn't a issue. Just sand, primer and repaint.Anodes don't work out of the water. (not trying to be funny). If you want anodes just use aluminum because they will work in both fresh and salt/brackish water

 

[jerryjerry05]

Re: Slowing corrosion on VP drive?

Once you put your boat in salt water. There is very little you can do to rince,clean away the salt.
It gets in and no amount of flushing and washing will remove it all.
I found adding a zinc to the transom and grounding it to the electrical system will help some.

 

[noclutch]

Re: Slowing corrosion on VP drive?

Just got back from a weekend in salt to brackish water. Being susceptible to snake oil pitches etc , during the clean up yesterday I did spray/rinse the outdrive with Salt X and ran Salt away through the muffs as I usually do after such an outing. Dunno whether that will do anything or not though- any feedback on these products??
I guess I was just a bit surprised to see corrosion like I have on a trailered boats drive ( relative to my fathers Merc I/O I had access to in the 70's, who's anode fin showed much erosion )