Bottom Pain cause of B3 Corrosion???

Summerwind

Summerwind

New Member
Aug 21, 2008
275
Phila
Boat Info
2008 Formula 310 Sun Sport
Engines
377 x 2 w/BIII
Bottom Paint cause of B3 Corrosion???

I was just told by an authorized mercury service center, that the reason my b3s corroded is that I painted to close to the sea strainers, drain plug and trim tabs? Say what??

I know not to paint against the OD but I have never heard of not painting near/next to those other areas.

Thoughts?
 
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That doesn't sound correct to me...... I have always painted my tabs and thru-hulls and never had an issue. I would be more inclined to think you had a bad Mercathode or REALLY bad dock power before I would lay blame on painting those items.
 
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my B-3 look like crap.. it is because of dock power.. the guy next to me has B-2's with aluminum props and his looks fine.
 
Check your galvanic isolator and maybe hang a few zinc groupers off the side for added protection. You may want to pick up a silver-silver-chloride probe so that you can monitor your corrosion rate and take steps to prevent this happening again. I learned how crucial this is when I had my Marinette and my steel-hulled Chris Craft. Get all power cables out of the water around your boat, check for bad cabling in your bilge that may be shorting in water and complain to the dock manager.

On my B-II's that I had on my AJ, I went from SS props to aluminum just so I would not have this issue (which B-II's rarely do anyway). Welcome to the wonderful world of owning Bravo-III's!!!
 
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What type of anodes do you have? Did a local Merc dealer recommend a certain type? What brand?

EDIT: I agree that painting those items is unlikely to cause severe damage to your drives. Could it cause some? Well, bottom paint for fiberglass is meant for fiberglass and not metal items. It probably all depends on exactly what is used, the water you're in... lot's of factors.
 
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All of the pictures of corrosion on BIII's that have been posted on this site and others are typically in the same area on the outdrive. You can't tell me we all have bad galvanic isolators or problems at our docks. I believe the problem is all with the BIII. IMO
 
The service center telling me its the bottom paint, is like saying I use the wrong wax.
 
From the factory (at least on my boat) Sea Ray paints the trim tabs with bottom paint. They also leave approximately 1 inch unpainted around the outdrive. If you paint the outdrive, then yes it will corrode because of the Copper in the paint. But if the outdrive is unpainted then I don't see how the bottom paint is at fault here.

What you have been told does not seem correct to me. Did they at least test your mercathode to see if it was operating properly? If there is a problem with the mercathode then for sure you will get corrosion.

Dave
 
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I have always painted my trim tabs and all underwater hardware with bottom paint. I always use Micron CSC. The only thing I did not paint with bottom paint when I had I/O's was the outdrives. I left an inch and a half around each. I painted the outdrives with Trilux-33 (brushed, not sprayed). Never had an issue.

Although a member here is correct that all B-III could not be having the same issues because of power and/or galvanic isolator issues, I strongly believe that these may greatly compound the problems with corrosion. A very small power or isolator issue may not make any difference to a B-I, II or Alpha, but it compound the problem with the B-III. I would still check into this.

How is your bonding system? Hvae you checked that? Usually that will have different effects (i.e. your other underwater HW will disintegrate first). Worth a check att his point.

The long and short of all these posts though is that something somewhere is putting current into the water. Whether it is stray current coming from bad power, stray current that you are interjecting yourself, or improperly protected metal..... If your galvanic system (i.e. zincs and Mercathode) are not 100% on these B-III's, you WILL get corrosion issues.

Next step, buy a silver-silver-chloride probe and go fishing for the cause.
 
Dave S; You know, I was so taking back when 1st told, I didnt ask about the merc cathodes. Im making calls right now.

Yes there is a 1.5 " seperation between the drives and the paint.
 
Summerwind said:
Dave S; You know, I was so taking back when 1st told, I didnt ask about the merc cathodes. Im making calls right now.

Yes there is a 1.5 " seperation between the drives and the paint.
Click to expand...

As mentioned above (especially if they tell you the mercathode is working) you also need to verify that your bonding system is nice and sound. That will take a technician (or you can do it your self if so inclined) and that your Galvanic Isolater is working.

I have been through many corrosion issues on my B3 because at our lake they all seem to corrode regardless of how carefull you are. By installing extra anodes on the transom along with the heavy duty Mercathode Controller I was able to localize the corrosion to the prop hub and skeg. The rest of my drive is corrosion free even after being in the water year round for nearly four years. However, the prop hub corrosion got so bad that Merc finally replaced my lower unit primarily becasue the bearing carrier was severly corroded. Most of the time when I see boats that have been wet slipped on our Lake for any length of time, the B3s are all very corroded.

One other question since you own a Formula............do your drives have the Simrek Drive Shower installed on them? http://www.driveshowers.com/ It was my understanding that Formula was installing these on all of their new performance boats right at the factory. While I love the Simrek Drive Shower (I had one on my 240SD) it is another chunk of Stainless that could possibly contribute to corrosion if your boat is wet slipped.
 
I guess a simple cure would be to go with aluminum or composite props...... That would get appx 50 pounds of SS, per outdrive, out of the water.....
 
Dave S said:
As mentioned above (especially if they tell you the mercathode is working) you also need to verify that your bonding system is nice and sound. That will take a technician (or you can do it your self if so inclined) and that your Galvanic Isolater is working.

I have been through many corrosion issues on my B3 because at our lake they all seem to corrode regardless of how carefull you are. By installing extra anodes on the transom along with the heavy duty Mercathode Controller I was able to localize the corrosion to the prop hub and skeg. The rest of my drive is corrosion free even after being in the water year round for nearly four years. However, the prop hub corrosion got so bad that Merc finally replaced my lower unit primarily becasue the bearing carrier was severly corroded. Most of the time when I see boats that have been wet slipped on our Lake for any length of time, the B3s are all very corroded.

One other question since you own a Formula............do your drives have the Simrek Drive Shower installed on them? http://www.driveshowers.com/ It was my understanding that Formula was installing these on all of their new performance boats right at the factory. While I love the Simrek Drive Shower (I had one on my 240SD) it is another chunk of Stainless that could possibly contribute to corrosion if your boat is wet slipped.
Click to expand...

No drive showers.
I was told by the tech, his 1st reading was 650 MV after removing the paint from the tru-hull fitings (2 sea strainers) his 2nd reading was 750 to 800 MV.
Formula is talking with its electrical engineers and with Merc.
 
Summerwind said:
No drive showers.
I was told by the tech, his 1st reading was 650 MV after removing the paint from the tru-hull fitings (2 sea strainers) his 2nd reading was 750 to 800 MV.
Formula is talking with its electrical engineers and with Merc.
Click to expand...

Those readings will change depending how close they are taken to the drives. Mercury has a recommended distance to take the readings or the readings may show too high or too low. Some techs do not seem to be aware of this distance thing. The Mercury factory reps can tell them what the distance ought to be.
 
Here's something that I've been wondering. But first, yes I work at a Sea Ray dealership, but this is simply a question for those "more in the know" than me about anode composition.

I'm wondering... I've often heard (and been told) that different companies produce anodes (let's say aluminum, for sake of argument) with slightly different chemical make-ups. Now, I've never researched this any further so I'm hoping someone can help to verify/nullify this. Let's face it, we know what the answer is going to be if I call Merc!

If this is true, could that help explain the problem? Let's say Merc's aluminum anode was developed specifically to fight the inherent corrosion problem with the B3. Does a company like BoatZincs use the same formulation? Do the people having major problems use an aftermarket company, when maybe using the Merc product would help? I dunno.

I know enough about anodes to know things like... even though a boat may see only fresh water, Magnesium may not be the best choice. I also know that some waters are just plain going to be harder on anodes than others, no matter what you do. But I'd really like to know more about whether or not using Merc anodes is indeed better.

By the way, personally I use aluminum anodes by an aftermarket company... Navalloy. "According to the literature", they're chemical composition is superior as it contains some Zinc and Indium (what the heck the Indium is good for, I don't know). I only mention this to hammer home the point that I'm not trying to promote the Merc product - just genuinely interested.
 
Good News: Merc has agreed to replace both ODs :smt038
Merc said; "its only bottom paint requirement is the 1.5' threshold around the transom bracket" which was followed.

Thanks for the support and feedback.
 
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